Internet DRAFT - draft-rcross-sip
draft-rcross-sip
Network Working Group S. Wadhwa
Internet-Draft Alcatel-Lucent
Intended status: Standards Track J. Moisand
Expires: August 6, 2011 Juniper Networks
T. Haag
Deutsche Telekom
N. Voigt
Nokia Siemens Networks
T. Taylor, Ed.
Huawei Technologies
February 2, 2011
Protocol for Access Node Control Mechanism in Broadband Networks
draft-ietf-ancp-protocol-15
Abstract
This document describes the Access Node Control Protocol (ANCP).
ANCP operates between a Network Access Server (NAS) and an Access
Node (e.g., a Digital Subscriber Line Access Multiplexer (DSLAM)) in
a multi-service reference architecture in order to perform QoS-
related, service-related and subscriber-related operations. Use
cases for ANCP are documented in RFC 5851. As well as describing the
base ANCP protocol, this document specifies capabilities for Digital
Subscriber Line (DSL) topology discovery, line configuration, and
remote line connectivity testing. The design of ANCP allows for
protocol extensions in other documents if they are needed to support
other use cases and other access technologies.
ANCP is based on GSMPv3 (RFC 3292), but with many modifications and
extensions, to the point that the two protocols are not
interoperable.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
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This Internet-Draft will expire on August 6, 2011.
Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 6
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 7
2. Broadband Access Aggregation . . . . . . . . . . . . . . . . . 8
2.1. ATM-based Broadband Aggregation . . . . . . . . . . . . . 8
2.2. Ethernet-Based Broadband Aggregation . . . . . . . . . . . 10
3. Access Node Control Protocol -- General Aspects . . . . . . . 10
3.1. Protocol Version . . . . . . . . . . . . . . . . . . . . . 10
3.2. ANCP Transport . . . . . . . . . . . . . . . . . . . . . . 11
3.3. Encoding of Text Fields . . . . . . . . . . . . . . . . . 12
3.4. Treatment of Reserved and Unused Fields . . . . . . . . . 12
3.5. Use of the GSMPv3 Adjacency Protocol . . . . . . . . . . . 12
3.5.1. ANCP Adjacency Message Format . . . . . . . . . . . . 12
3.5.2. ANCP Adjacency Procedures . . . . . . . . . . . . . . 15
3.6. ANCP General Message Formats . . . . . . . . . . . . . . . 17
3.6.1. The ANCP Message Header . . . . . . . . . . . . . . . 17
3.6.2. The ANCP Message Body . . . . . . . . . . . . . . . . 25
3.7. General Principles for the Design of ANCP Messages . . . . 26
4. Generally Useful ANCP Messages and TLVs . . . . . . . . . . . 27
4.1. Provisioning Message . . . . . . . . . . . . . . . . . . . 27
4.2. Generic Response Message . . . . . . . . . . . . . . . . . 28
4.3. Target TLV . . . . . . . . . . . . . . . . . . . . . . . . 30
4.4. Command TLV . . . . . . . . . . . . . . . . . . . . . . . 30
4.5. Status-Info TLV . . . . . . . . . . . . . . . . . . . . . 31
5. Introduction To ANCP Capabilities For Digital Subscriber
Lines (DSL) . . . . . . . . . . . . . . . . . . . . . . . . . 32
5.1. DSL Access Line Identification . . . . . . . . . . . . . . 33
5.1.1. Control Context (Informative) . . . . . . . . . . . . 33
5.1.2. TLVs For DSL Access Line Identification . . . . . . . 34
6. ANCP Based DSL Topology Discovery . . . . . . . . . . . . . . 37
6.1. Control Context (Informative) . . . . . . . . . . . . . . 37
6.2. Protocol Requirements . . . . . . . . . . . . . . . . . . 39
6.2.1. Protocol Requirements On the AN Side . . . . . . . . . 39
6.2.2. Protocol Requirements On the NAS Side . . . . . . . . 40
6.3. ANCP Port UP and Port DOWN Event Message Descriptions . . 40
6.4. Procedures . . . . . . . . . . . . . . . . . . . . . . . . 42
6.4.1. Procedures On the AN Side . . . . . . . . . . . . . . 42
6.4.2. Procedures On the NAS Side . . . . . . . . . . . . . . 43
6.5. TLVs For DSL Line Attributes . . . . . . . . . . . . . . . 43
6.5.1. DSL-Line-Attributes TLV . . . . . . . . . . . . . . . 43
6.5.2. DSL-Type TLV . . . . . . . . . . . . . . . . . . . . . 44
6.5.3. Actual-Net-Data-Rate-Upstream TLV . . . . . . . . . . 44
6.5.4. Actual-Net-Data-Rate-Downstream TLV . . . . . . . . . 44
6.5.5. Minimum-Net-Data-Rate-Upstream TLV . . . . . . . . . . 45
6.5.6. Minimum-Net-Data-Rate-Downstream TLV . . . . . . . . . 45
6.5.7. Attainable-Net-Data-Rate-Upstream TLV . . . . . . . . 45
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6.5.8. Attainable-Net-Data-Rate-Downstream TLV . . . . . . . 45
6.5.9. Maximum-Net-Data-Rate-Upstream TLV . . . . . . . . . . 46
6.5.10. Maximum-Net-Data-Rate-Downstream TLV . . . . . . . . . 46
6.5.11. Minimum-Net-Low-Power-Data-Rate-Upstream TLV . . . . . 46
6.5.12. Minimum-Net-Low-Power-Data-Rate-Downstream TLV . . . . 46
6.5.13. Maximum-Interleaving-Delay-Upstream TLV . . . . . . . 47
6.5.14. Actual-Interleaving-Delay-Upstream TLV . . . . . . . . 47
6.5.15. Maximum-Interleaving-Delay-Downstream TLV . . . . . . 47
6.5.16. Actual-Interleaving-Delay-Downstream . . . . . . . . . 47
6.5.17. DSL-Line-State TLV . . . . . . . . . . . . . . . . . . 47
6.5.18. Access-Loop-Encapsulation TLV . . . . . . . . . . . . 48
7. ANCP based DSL Line Configuration . . . . . . . . . . . . . . 49
7.1. Control Context (Informative) . . . . . . . . . . . . . . 49
7.2. Protocol Requirements . . . . . . . . . . . . . . . . . . 50
7.2.1. Protocol Requirements On the NAS Side . . . . . . . . 51
7.2.2. Protocol Requirements On the AN Side . . . . . . . . . 51
7.3. ANCP Port Management (Line Configuration) Message
Format . . . . . . . . . . . . . . . . . . . . . . . . . . 51
7.4. Procedures . . . . . . . . . . . . . . . . . . . . . . . . 54
7.4.1. Procedures On the NAS Side . . . . . . . . . . . . . . 54
7.4.2. Procedures On the AN Side . . . . . . . . . . . . . . 54
7.5. TLVs For DSL Line Configuration . . . . . . . . . . . . . 55
7.5.1. Service-Profile-Name TLV . . . . . . . . . . . . . . . 55
8. ANCP-Based DSL Remote Line Connectivity Testing . . . . . . . 55
8.1. Control Context (Informative) . . . . . . . . . . . . . . 55
8.2. Protocol Requirements . . . . . . . . . . . . . . . . . . 56
8.2.1. Protocol Requirements On the NAS Side . . . . . . . . 56
8.2.2. Protocol Requirements On the AN Side . . . . . . . . . 57
8.3. Port Management (OAM) Message Format . . . . . . . . . . . 57
8.4. Procedures . . . . . . . . . . . . . . . . . . . . . . . . 58
8.4.1. NAS-Side Procedures . . . . . . . . . . . . . . . . . 58
8.4.2. AN-Side Procedures . . . . . . . . . . . . . . . . . . 59
8.5. TLVs For the DSL Line Remote Connectivity Testing
Capability . . . . . . . . . . . . . . . . . . . . . . . . 60
8.5.1. OAM-Loopback-Test-Parameters TLV . . . . . . . . . . . 60
8.5.2. Opaque-Data TLV . . . . . . . . . . . . . . . . . . . 61
8.5.3. OAM-Loopback-Test-Response-String TLV . . . . . . . . 61
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 61
9.1. Summary . . . . . . . . . . . . . . . . . . . . . . . . . 61
9.2. IANA Actions . . . . . . . . . . . . . . . . . . . . . . . 62
10. Security Considerations . . . . . . . . . . . . . . . . . . . 67
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 69
12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 69
12.1. Normative References . . . . . . . . . . . . . . . . . . . 69
12.2. Informative References . . . . . . . . . . . . . . . . . . 69
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 70
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1. Introduction
This draft defines a new protocol, the Access Node Control Protocol
(ANCP), to realize a control plane between a service-oriented layer 3
edge device (the Network Access Server, NAS) and a layer 2 Access
Node (e.g., Digital Subscriber Line Access Module, DSLAM) in order to
perform QoS-related, service-related and subscriber-related
operations. The requirements for ANCP and the context within which
it operates are described in [RFC5851].
The protocol specification takes GSMPv3 [RFC3292] as a starting
point, and the implementor is directed to parts of [RFC3292] for the
specification of some aspects of the protocol. However, ANCP
introduces so many extensions and modifications to GSMPv3 that the
two protocols are not interoperable.
ANCP provides its services to control applications operating in the
AN and NAS respectively. This relationship is shown in Figure 1.
Specification of the control applications is beyond the scope of this
document, but informative partial descriptions are provided as
necessary to give a context for the operation of the protocol.
Access Node Network Access Server
+--------------------+ +--------------------+
| +----------------+ | | +----------------+ |
| | AN Control | | | | NAS Control | |
| | Application | | | | Application | |
| +----------------+ | | +----------------+ |
| +----------------+ | | +----------------+ |
| | ANCP Agent | | ANCP Messages | | ANCP Agent | |
| | (AN side) |<----------------------->| (NAS side) | |
| +----------------+ | | +----------------+ |
+--------------------+ +--------------------+
Figure 1: Architectural Context For the Access Node Control Protocol
At various points in this document, information flows between the
control applications and ANCP are described. The purpose of such
descriptions is to clarify the boundary between this specification
and, for example, [TR-147]. There is no intention to place limits on
the degree to which the control application and the protocol
implementation are integrated.
This specification specifies ANCP transport over TCP/IP. TCP
encapsulation for ANCP is as defined for GSMPv3 in [RFC3293]. The
alternative GSMPv3 encapsulation directly over Ethernet and ATM as
defined in [RFC3293] is not considered for ANCP.
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The organization of this document is as follows:
o The next two sub-sections introduce some terminology that will be
useful in understanding the rest of the document.
o Section 2 provides a description of the access networks within
which ANCP will typically be deployed.
o Section 3 specifies generally applicable aspects of the ANCP
protocol.
o Section 4 specifies some messages and TLVs intended for use by
multiple capabilities spanning multiple technologies.
o Section 5 and the three following sections describe and specify
the ANCP implementation of three capabilities applicable to the
control of DSL access technology: topology discovery, line
configuration, and remote line connectivity testing.
o Section 9 is the IANA Considerations section. Some codepoints are
added to existing GSMPv3 registries set up by [RFC3292], but a
number of new ANCP-specific registries are also defined.
o Section 10 addresses security considerations relating to ANCP,
beginning with the requirements stated in [RFC5713].
RFC EDITOR'S NOTE: the following paragraph should be deleted upon
publication.
At the time of writing of this specification some implementations of
the ANCP protocol based on pre-standards drafts are already
available. These early-draft implementations use protocol version/
sub-version 3.1. The standard ANCP protocol will use version/
sub-version 3.2 Adopting a new sub-version value provides a way to
disambiguate the two protocols and provides support for running a
pre-standard and a standards compliant ANCP implementation on any
given ANCP node. The mechanism used to identify the protocol
version/sub-version is part of the adjacency negotiation process and
it is described in detail in Section 3.5. NOTE: this mechanism does
not guarantee backwards compatibility of the published ANCP
specification with those early-draft implementations.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
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This specification uses requirements language in lower case and
between quotation marks (e.g., "must") to denote requirements on the
interface between ANCP and the control application. Such
requirements are inherently untestable but need to be taken into
account by the implementor.
1.2. Terminology
This section repeats some definitions from [RFC5851], but also adds
definitions for terms used only in this document.
Access Node (AN): [RFC5851] Network device, usually located at a
service provider central office or street cabinet that terminates
access (local) loop connections from subscribers. In case the
access loop is a Digital Subscriber Line (DSL), the Access Node
provides DSL signal termination, and is referred to as a DSL
Access Multiplexer (DSLAM).
Network Access Server (NAS): [RFC5851] Network element which
aggregates subscriber traffic from a number of Access Nodes. The
NAS is an enforcement point for policy management and IP QoS in
the access network. It is also referred to as a Broadband Network
Gateway (BNG) or Broadband Remote Access Server (BRAS).
Home Gateway (HGW): Network element that connects subscriber devices
to the Access Node and the access network. In the case of DSL,
the Home Gateway is a DSL network termination that may operate
either as a layer 2 bridge or as a layer 3 router. In the latter
case, such a device is also referred to as a Routing Gateway (RG).
ANCP agent: A logical entity that implements the ANCP protocol in
the Access Node (AN-side) or NAS (NAS-side).
Access Node control adjacency: (modified from [RFC5851]) the
relationship between the AN-side ANCP agent and the NAS-side ANCP
agent for the purpose of exchanging Access Node Control Protocol
messages. The adjacency may either be up or down, depending on
the result of the Access Node Control adjacency protocol
operation.
ANCP capability: A specific set of ANCP messages, message content,
and procedures required to implement a specific use case or set of
use cases. Some ANCP capabilities are applicable to just one
access technology while others are technology independent. The
capabilities applicable to a given ANCP adjacency are negotiated
during adjacency startup.
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Type-Length-Value (TLV): a data structure consisting of a sixteen-
bit type field, a sixteen-bit length field, and a variable-length
value field padded to the nearest 32-bit word boundary, as
described in Section 3.6.2. The value field of a TLV can contain
other TLVs. An IANA registry is maintained for values of the ANCP
TLV Type field.
Net data rate: [RFC5851] defined by ITU-T G.993.2 [G.993.2], Section
3.39, i.e., the portion of the total data rate that can be used to
transmit user information (e.g., ATM cells or Ethernet frames).
It excludes overhead that pertains to the physical transmission
mechanism (e.g., trellis coding in the case of DSL). It includes
TPS-TC (Transport Protocol Specific - Transmission Convergence)
encapsulation; this is zero for ATM encapsulation, and non-zero
for 64/65 encapsulation.
Line rate: [RFC5851] defined by ITU-T G.993.2. It contains the
complete overhead including Reed-Solomon and trellis coding.
DSL multi-pair bonding: method for bonding (or aggregating) multiple
xDSL lines into a single bi-directional logical link, henceforth
referred to in this draft as "DSL bonded circuit". DSL "multi-
pair" bonding allows an operator to combine the data rates on two
or more copper pairs, and deliver the aggregate data rate to a
single customer. ITU-T recommendations G.998.1 and G.998.2
respectively describe ATM and Ethernet based multi-pair bonding.
2. Broadband Access Aggregation
2.1. ATM-based Broadband Aggregation
The end to end DSL network consists of network service provider (NSP)
and application service provider (ASP) networks, regional/access
network, and customer premises network. Figure 2 shows ATM broadband
access network components.
The regional/access network consists of the regional network, Network
Access Server (NAS), and the access network as shown in Figure 2.
Its primary function is to provide end-to-end transport between the
customer premises and the NSP or ASP.
The Access Node terminates the DSL signal. It may be in the form of
a DSLAM in the central office, or a remote DSLAM, or a Remote Access
Multiplexer (RAM). The Access Node is the first point in the network
where traffic on multiple DSL lines will be aggregated onto a single
network.
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The NAS performs multiple functions in the network. The NAS is the
aggregation point for subscriber traffic. It provides aggregation
capabilities (e.g. IP, PPP, ATM) between the Regional/Access Network
and the NSP or ASP. These include traditional ATM-based offerings
and newer, more native IP-based services. This includes support for
Point-to-Point Protocol over ATM (PPPoA) and PPP over Ethernet
(PPPoE), as well as direct IP services encapsulated over an
appropriate layer 2 transport.
Beyond aggregation, the NAS is also the enforcement point for policy
management and IP QoS in the regional/access networks. To allow IP
QoS support over an existing non-IP-aware layer 2 access network
without using multiple layer 2 QoS classes, a mechanism based on
hierarchical scheduling is used. This mechanism, defined in
[TR-059], preserves IP QoS over the ATM network between the NAS and
the routing gateway (RG) at the edge of the subscriber network, by
carefully controlling downstream traffic in the NAS, so that
significant queuing and congestion does not occur further down the
ATM network. This is achieved by using a diffserv-aware hierarchical
scheduler in the NAS that will account for downstream trunk
bandwidths and DSL synchronization rates.
[RFC5851] provides detailed definitions of the functions of each
network element in the broadband reference architecture.
Access Customer
<--- Aggregation --> <------- Premises ------->
Network Network
+------------------+ +--------------------------+
+---------+ +---+ | +-----+ +------+ | |+-----+ +---+ +---------+ |
NSP| | +-|NAS|-| |ATM |-|Access| --||DSL |-|HGW|-|Subscriber||
---+ Regional| | +---+ | +-----+ | Node | | ||Modem| +---+ |Devices ||
|Broadband| | +---+ | +------+ | |+-----+ +----------+|
ASP|Network |-+-|NAS| +--------------|---+ +--------------------------+
---+ | | +---+ | +--------------------------+
| | | +---+ | |+-----+ +---+ +----------+|
+---------+ +-|NAS| +-----|| DSL |-|HGW|-|Subscriber||
+---+ ||Modem| +---+ |Devices ||
|+-----+ +----------+|
+--------------------------+
HGW : Home Gateway
NAS : Network Access Server
Figure 2: ATM Broadband Aggregation Topology
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2.2. Ethernet-Based Broadband Aggregation
The Ethernet aggregation network architecture builds on the Ethernet
bridging/switching concepts defined in IEEE 802. The Ethernet
aggregation network provides traffic aggregation, class of service
distinction, and customer separation and traceability. VLAN tagging
defined in IEEE 802.1Q and being enhanced by IEEE 802.1ad is used as
standard virtualization mechanism in the Ethernet aggregation
network. The aggregation devices are "provider edge bridges" defined
in IEEE 802.ad.
Stacked VLAN tags provide one possible way to create equivalent of
"virtual paths" and "virtual circuits" in the aggregation network.
The "outer" vlan can be used to create a form of "virtual path"
between a given DSLAM and a given NAS. "Inner" VLAN tags create a
form of "virtual circuit" on a per DSL line basis. This is the 1:1
VLAN allocation model. An alternative model is to bridge sessions
from multiple subscribers behind a DSLAM into a single VLAN in the
aggregation network. This is the N:1 VLAN allocation model. Section
1.6 of [TR-101] provides brief definitions of these two models, while
section 2.5.1 describes them in more detail.
3. Access Node Control Protocol -- General Aspects
This section specifies aspects of the Access Node Control Protocol
(ANCP) that are generally applicable. As indicated above, ANCP is
derived from GSMPv3 [RFC3292]. Reference to [RFC3292] is made where
this is applicable, but ANCP introduces numerous modifications and
extensions to the basic GSMPv3 protocol. Moreover, ANCP uses only a
subset of the messages, message contents, and procedures defined for
GSMPv3, and defines additional messages, message contents, and
procedures that are specific to ANCP.
3.1. Protocol Version
GSMPv3 messages contain an 8-bit protocol version field. As
described below, ANCP subdivides this into two 4-bit sub-fields, for
version and sub-version. Implementations of this version of the ANCP
specification MUST set the version sub-field to 3 and the sub-version
sub-field to 1. That is, the hexadecimal representation of the value
of the complete protocol version field MUST be 0x31.
RFC EDITOR'S NOTE: please change the value of sub-version in the
above paragraph to 2 (respectively a version field value of 0x32) in
the published specification. For an explanation see the Introduction
above.
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3.2. ANCP Transport
This document specifies the use of TCP/IP for transport of ANCP
messages. Other specifications may introduce additional transports
in the future.
In the case of ATM access, a separate PVC (control channel)
capable of transporting IP MAY be configured between NAS and the
AN for ANCP messages.
In the case of an Ethernet access/aggregation network, a typical
practice is to send the Access Node Control Protocol messages over
a dedicated Ethernet virtual LAN (VLAN) using a separate VLAN
identifier (VLAN ID).
When transported over TCP, ANCP messages MUST use the encapsulation
specified for GSMPv3 messages carried over TCP in [RFC3293]. This
encapsulation consists of a four-byte header field prepended to the
ANCP message as shown in Figure 3.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier (0x880C) | Length |
|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ ANCP Message ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Encapsulation of ANCP Messages Over TCP/IP
The fields of the encapsulating header are as follows:
Identifier: This 2-byte field identifies a GSMP or ANCP message.
The type code for GSMP and ANCP messages is 0x880C (i.e., the same
as GSMP's Ethertype).
Length: This 2-byte unsigned integer indicates the total length of
the ANCP message, not including the 4-byte encapsulating header.
The Access Node MUST initiate the TCP session to the NAS. This is a
deviation from [RFC3293], which requires the controller to initiate
the TCP connection to the switch.
This is necessary to avoid static address provisioning on the NAS
for all the ANs that are being served by the NAS. It is easier to
configure a given AN with the single IP address of the NAS that
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serves the AN.
The NAS MUST listen for incoming connections from the Access Nodes.
Port 6068 is used for TCP connection.
In the event of an ANCP transport protocol failure, all pending ANCP
messages destined to the disconnected recipient SHOULD be discarded
until the transport connection is re-established.
3.3. Encoding of Text Fields
In ANCP, all text fields use UTF-8 encoding [RFC3629]. Note that US
ASCII characters have the same representation when coded as UTF-8 as
they do when coded according to [US_ASCII].
When extracting text fields from a message, the ANCP agent MUST NOT
assume that the fields are zero-terminated.
3.4. Treatment of Reserved and Unused Fields
ANCP messages contain a number of fields that are unused or reserved.
Some fields are always unused (typically because they were inherited
from GSMPv3 but are not useful in the ANCP context). Others are
reserved in the current specification, but are provided for
flexibility in future extensions to ANCP. Both reserved and unused
fields MUST be set to zeroes by the sender and MUST be ignored by the
receiver.
Unused bits in a flag field are shown in figures as 'x'. The above
requirement (sender set to zero, receiver ignore) applies to such
unused bits.
3.5. Use of the GSMPv3 Adjacency Protocol
Section 11 of [RFC3292] defines the GSMPv3 adjacency protocol. ANCP
reuses the GSMPv3 adjacency protocol to synchronize the NAS and
Access Nodes and maintain the ANCP session. After the TCP connection
is established, adjacency protocol messages MUST be exchanged as
specified in Section 11 of [RFC3292], subject to the additional
specifications of this section. ANCP messages other than adjacency
protocol messages MUST NOT be sent until the adjacency protocol has
achieved synchronization.
3.5.1. ANCP Adjacency Message Format
The GSMPv3 adjacency message format defined in Section 11 of
[RFC3292] is modified and extended for ANCP as shown in Figure 4
below. The 8-bit "version" field in the GSMPv3 adjacency protocol
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messages is modified to carry the ANCP version (four bits) and sub-
version (four bits). See Section 3.1 for the values to set for
version and sub-version for the present version of this
specification.
The semantics and suggested values for the Code, Sender Name,
Receiver Name, Sender Instance, and Receiver Instance fields are as
defined in Section 11 of [RFC3292]. The Sender Port, and Receiver
Port SHOULD be set to 0 by both ends. The pType field MAY be set to
0 (No Partition) or another value depending on local configuration.
The pFlag SHOULD be set to 1 (New Adjacency).
In addition to the modification of the version field, ANCP adds
several new fields. These are described below the figure.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ver | Sub | Message Type | Timer |M| Code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender Name |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| Receiver Name |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Receiver Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PType | PFlag | Sender Instance |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Partition ID | Receiver Instance |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | # of Caps | Total Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Capability Fields ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: ANCP Adjacency Message Format
The fields added by ANCP are as follows:
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Reserved (8 bits): reserved for use by a future version of this
specification.
# of Caps: indicates the number of capability fields that follow.
Total Length: indicates the total number of bytes occupied by the
capability fields that follow.
Capability Fields: Each capability field indicates one ANCP
capability supported by the sender of the adjacency message.
Negotiation of a common set of capabilities to be supported within
the ANCP session is described in Section 3.5.2. The detailed
format of a capability field is shown in Figure 5 and described
below.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Capability Type | Capability Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ ~
~ Capability Data ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: Capability Field
The sub-fields of this structure are as follows:
Capability Type: indicates the specific capability supported. An
IANA registry exists for values of this sub-field. The values
specified by this document are listed below.
Capability Length: the number of bytes of data contained in the
Capability Data sub-field, excluding padding. If the definition
of a particular capability includes no capability data, the value
of the Capability Length sub-field is zero.
Capability Data: contains data associated with the capability as
specified for that capability. If the definition of a particular
capability includes no capability data, the Capability Data sub-
field is absent (has zero length). Otherwise, the Capability Data
sub-field MUST be padded with zeroes as required to terminate on a
4-byte word boundary. The possibility of specifying capability
data provides the flexibility to advertise more than the mere
presence or absence of a capability if needed.
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The following capabilities are defined for ANCP as applied to DSL
access:
o Capability Type : DSL Topology Discovery = 0x01
Access technology: DSL
Length (in bytes) : 0
Capability Data : NULL
For the detailed protocol specification of this capability see
Section 6.
o Capability Type : DSL Line Configuration = 0x02
Access technology: DSL
Length (in bytes) : 0
Capability Data : NULL
For the detailed protocol specification of this capability see
Section 7.
o Capability Type : DSL Remote Line Connectivity Testing = 0x04
Access technology: DSL
Length (in bytes) : 0
Capability Data : NULL
For the detailed protocol specification of this capability see
Section 8.
3.5.2. ANCP Adjacency Procedures
Before beginning adjacency negotiation, the ANCP agent and the
control application "must" agree on the set of capabilities that they
support. This agreement "must" include the transfer of any
application-level information required to build the Capability Data
fields within the Capability structures. Note that none of the
capabilities specified in this document require any such information.
The NAS MUST set the M-flag in the SYN message (signifying it is the
master). Once the adjacency is established, periodic adjacency
messages (type ACK) MUST be exchanged. The default for the ACK
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interval to be advertised in the adjacency messages is 25 seconds for
ANCP. The actual value SHOULD be configurable and is a deployment
choice. It is RECOMMENDED that both ends specify the same timer
value; to achieve this, each end SHOULD compare the timer value in
the first adjacency message it receives with its own preferred value
and agree to use the higher of the two values. That is, the node
that receives a higher timer value than its own SHOULD reply in its
subsequent adjacency messages (such as SYNACK, ACK) with the higher
timer value.
In the adjacency protocol the version and sub-version fields are used
for version negotiation. The version negotiation MUST be completed
before synchronisation is achieved. In a SYN message the version/
sub-version fields always contain the highest version understood by
the sender. A receiver receiving a SYN message with a version/
sub-version higher than it understands MUST silently discard that
message. A receiver receiving a SYN message with a version/
sub-version within the range of versions that it understands MUST
reply with a SYNACK with the version/sub-version from the received
SYN in its ANCP version/sub-version fields. This defines the
version/sub-version of the ANCP protocol to be used while the
adjacency remains synchronized. All other ANCP messages within the
session MUST use the agreed version in the version/sub-version
fields.
Both the NAS and the Access Node MUST advertise supported
capabilities in the adjacency messages they send. The same message
MAY advertise capabilities for any mixture of access technologies.
If a received adjacency message indicates no support for a capability
that is supported by the receiving device, it MUST disable the
capability locally and MUST send an updated adjacency message with
the corresponding capability field omitted to match the received
capability set. This process will eventually result in both sides
agreeing on the maximal common set of supported capabilities. The
adjacency MUST NOT come up if that common set is empty.
Subsequent to adjacency startup, if the adjacency times out on either
end, due to not receiving an adjacency message for a duration of (3 *
Timer value), where the timer value is negotiated as described above,
all the state received from the ANCP peer SHOULD be cleaned up, and
the TCP connection SHOULD be closed. The NAS MUST continue to listen
for new connection requests. The AN MUST try to re-establish the TCP
connection and both sides MUST attempt to re-establish the adjacency.
After initial synchronization, if at any time a capability mismatch
is detected, the adjacency MUST be brought down (RSTACK MUST be
generated by the device detecting the mismatch), and synchronization
MUST be re-attempted.
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The ANCP agent "must" notify the control application whenever an
adjacency is either synchronized or lost. When an adjacency is
synchronized, the notification "must" include the set of capabilities
negotiated with the peer along with any application-level information
conveyed in Capability Data fields.
3.6. ANCP General Message Formats
This section describes the general format of ANCP messages other than
the adjacency messages.
The GSMPv3 general message format, used by all GSMP messages other
than adjacency protocol messages, is defined in Section 3.1.1 of
GSMPv3 [RFC3292]. ANCP modifies this base GSMPv3 message format as
shown in Figure 6.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Vers | Sub | Message Type | Result| Code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Partition ID | Transaction Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|I| SubMessage Number | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Message Payload ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: ANCP General Message Format
3.6.1. The ANCP Message Header
The immediately visible differences from GSMPv3 are the subdivision
of the Version field into version and sub-version, and the
reallocation of space between Result and Code to enlarge the range
for Code. The 8-bit version field in the base GSMPv3 message header
is split into two 4 bit fields for carrying the version and a sub-
version of the ANCP protocol. The Result field in the message header
has been modified to be 4 bits long, and the Code field to be 12 bits
long.
A complete explanation of the header fields follows.
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3.6.1.1. Version and Sub-Version Fields
Together these fields reproduce the version of the ANCP protocol that
was agreed for the session during adjacency negotiation. See
Section 3.1 for the values to set for version and sub-version for the
present version of this specification.
3.6.1.2. Message Type Field
This field indicates the ANCP message type. Message type values are
registered in a common GSMPv3/ANCP IANA registry.
3.6.1.3. Result Field
The Result field is derived from GSMPv3 [RFC3292]. Ignore (0x0) is a
new value added by ANCP. The remaining Result values listed below
are a subset of those defined for GSMPv3. GSMPv3 expected the sender
of a request to choose between NAck (0x1) and AckAll (0x2) according
to its needs. ANCP specifies what Result value each request should
have. Responses indicate either Success (0x3) or Failure (0x4) as
the case may be.
Ignore: Res = 0x0 - Treat this field as a "no operation" and follow
the response procedures specified for the received message type.
Nack: Res = 0x1 - Result value indicating that a response is
expected to the request only in cases of failure caused during the
processing of the message contents or of the contained
directive(s).
AckAll: Res = 0x2 - Result value indicating that a response to the
message is requested in all cases.
Success: Res = 0x3 - Result value indicating that this is a response
and that the request was executed successfully. The Code field
for a successful result is typically 0, but MAY take on other
values as specified for particular message types.
Failure: Res = 0x4 - Result value indicating that this is a response
and that the request was not executed successfully. The receiver
of the response SHOULD take further action as indicated by the
Code value and any diagnostic data contained in a Status-Info TLV
included in the response.
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3.6.1.4. Code Field
This field gives further information concerning the result in a
response message. It is mostly used to pass an error code in a
failure response but can also be used to give further information in
a success response message or an event message. In a request
message, the Code field is not used and MUST be set to zero.
A number of code values are specified below. Specification of
additional Code values in extensions or updates to this document MUST
include the following information:
o Code value;
o One-line description;
o Where condition detected: (control application or ANCP agent);
o Further description (if any);
o Required additional information in the response message;
o Target (control application or ANCP agent at the peer that sent
the original request);
o Action RECOMMENDED for the receiving ANCP agent
In addition to any suggested action in the text which follows, the
Code value SHOULD be logged in a MIB. Where an action includes
resending of a request, a given request SHOULD NOT be re-sent more
than once.
ANCP agents MAY use any of the Code values specified in the IANA
registry "Global Switch Management Protocol version 3 (GSMPv3)
Failure Response Message Name Space" if they appear applicable. In
particular, the values 2, 6, 7, and 19 appear to be reusable and are
therefore documented below along with a few new ANCP-specific values.
Values 30 and 31 are also reusable, but are more appropriately
documented in a multicast extension document.
Code value: 2
* One-line description: Invalid request message
* Where condition detected: ANCP agent
* Further description: The request was a properly formed message
which violates the protocol through its timing or direction of
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transmission. The most likely reason for this outcome in the
field will be a race condition.
* Required additional information in the response message: none,
if the response message is of the same type as the request. As
specified in Section 4.2 if the response message is a Generic
Response message.
* Target: ANCP agent at the peer that sent the original request
* Action RECOMMENDED for the receiving ANCP agent: The original
request MAY be re-sent once only after a short delay. Inform
the control application with appropriate identification of the
failed transaction if the second attempt fails or no second
attempt is made.
Code value: 6
* One-line description: One or more of the specified ports are
down
* Where condition detected: control application
* Further description (if any): This Code value indicates a state
mismatch between the NAS and AN control applications, possibly
due to a race condition.
* Required additional information in the response message: if the
request identified multiple access lines or the response is a
Generic Response message, then the response MUST contain a
Status-Info TLV encapsulating TLV(s) containing the line
identifier(s) of the access lines that are not operational.
* Target: control application at the peer that sent the original
request
* Action RECOMMENDED for the receiving ANCP agent: indicate the
error and forward the line identifier(s) to the control
application.
Code value: 7
* One-line description: Invalid Partition ID
* Where condition detected: ANCP agent
* Further description: This indicates that the request used a
Partition ID value different from what was determined for this
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partition during adjacency negotiation, implying a state
mismatch between the ANCP agents.
* Required additional information in the response message: none,
if the response message is of the same type as the request. As
specified in Section 4.2 if the response message is a Generic
Response message.
* Target: ANCP agent at the peer that sent the original request
* Action RECOMMENDED for the receiving ANCP agent: If multiple
instances of this error occur, the requestor SHOULD cause the
adjacency for the partition to be reset and renegotiated by
sending an adjacency message with pType = 0 and Code = RSTACK
as described in Section 11.3 of [RFC3292].
NOTE: This specification provides no way for the NAS to do a
complete audit of the current state stored on the AN. Hence
renegotiation of the adjacency with pFlag = 2 (connection state
retained at the AN) MAY be attempted, but entails some risk of
state mismatch.
Code value: 19
* One-line description: Out of resources
* Where condition detected: ANCP protocol layer or control
application
* Further description: (e.g., memory exhausted, etc.). This Code
value MUST be reported only by the AN, and indicates a
condition that is probably unrelated to specific access lines
(although it may be related to the specific request).
* Required additional information in the response message: none,
if the response message is of the same type as the request. As
specified in Section 4.2 if the response message is a Generic
Response message.
* Target: ANCP agent at the peer that sent the original request
* Action RECOMMENDED for the receiving ANCP agent: If the NAS
receives this Code value from multiple requests for the same AN
in a short interval, it SHOULD reduce the rate at which it
sends requests in proportion to the rate at which requests are
failing with Code = 19. It MAY retry individual requests. If
only a specific request is failing with Code = 19, the ANCP
agent in the NAS MAY request the control application to
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decompose the request into simpler components if this is
possible.
Code value: 81
* One-line description: Request message type not implemented
* Where condition detected: ANCP agent
* Further description: This could indicate a mismatch in protocol
version or capability state. It is also possible that support
of a specific message is optional within some ANCP capability.
* Required additional information in the response message: none,
if the response message is of the same type as the request. As
specified in Section 4.2 if the response message is a Generic
Response message.
* Target: ANCP agent at the peer that sent the original request
* Action RECOMMENDED for the receiving ANCP agent: If the
receiver of this Code value expects that support of the message
type concerned is mandatory according to the capabilities
negotiated for the session, it SHOULD cause the adjacency for
the partition to be reset and renegotiated by sending an
adjacency message with pType = 0 and Code = RSTACK as described
in Section 11.3 of [RFC3292].
Code value: 83
* One-line description: Malformed message
* Where condition detected: ANCP agent
* Further description: This could be the result of corruption in
transit, or an error in implementation at one end or the other.
* Required additional information in the response message: none,
if the response message is of the same type as the request. As
specified in Section 4.2 if the response message is a Generic
Response message.
* Target: ANCP agent at the peer that sent the original request
* Action RECOMMENDED for the receiving ANCP agent: The request
SHOULD be re-sent once to eliminate the possibility of in-
transit corruption.
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Code value: 84
* One-line description: Mandatory TLV missing
* Where condition detected: ANCP agent
* Further description: none.
* Required additional information in the response message: the
response message MUST contain a Status-Info message that
encapsulates an instance of each missing mandatory TLV, where
the length is set to zero and the value field is empty (i.e.,
only the four-byte TLV header is present).
* Target: ANCP agent at the peer that sent the original request
* Action RECOMMENDED for the receiving ANCP agent: resend the
message with the missing TLV(s), if possible. Otherwise,
report the error to the control application with an indication
of the missing information required to construct the missing
TLV(s).
Code value: 85
* One-line description: Invalid TLV contents
* Where condition detected: ANCP agent
* Further description: the contents of one or more TLVs in the
request do not match the specifications provided for the those
TLVs.
* Required additional information in the response message: the
response MUST contain a Status-Info TLV encapsulating the
erroneous TLVs copied from the original request.
* Target: ANCP agent at the peer that sent the original request
* Action RECOMMENDED for the receiving ANCP agent: correct the
error and resend the request, if possible. Otherwise, report
the error to the control application with an indication of the
erroneous information associated with the invalid TLV(s).
Code value: 1280
* One-line description: One or more of the specified ports do not
exist
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* Where condition detected: control application
* Further description (if any): this may indicate a configuration
mismatch between the AN and the NAS or AAA.
* Required additional information in the response message: if the
request identified multiple access lines or the response is a
Generic Response message, then the response MUST contain a
Status-Info TLV encapsulating TLV(s) containing the rejected
line identifier(s).
* Target: control application at the peer that sent the original
request
* Action RECOMMENDED for the receiving ANCP agent: indicate the
error and forward the line identifiers to the control
application.
ANCP extensions defining new code values SHOULD use the range 256
(0x100) through 511 (0x1FF) for this purpose. The range of values
from 256 to 4095 is reserved for allocation by IETF consensus.
3.6.1.5. Partition ID
The Partition ID field is a 8 bit number which signifies a partition
on the AN. The AN and NAS MAY agree on the partition ID using one of
the following possible options:
o The partition ID MAY be configured on the AN and learned by the
NAS in the adjacency message; or
o The partition ID MAY be statically configured on the NAS as part
of configuring the neighbor information.
3.6.1.6. Transaction ID
The Transaction ID is a 24-bit field set by the sender of a request
message to associate a response message with the original request
message. Unless otherwise specified for a given message type, the
Transaction ID in request messages MUST be set to a value in the
range (1, 2^24 - 1). When used in this manner, the Transaction ID
sequencing MUST be maintained independently for each message type
within each ANCP adjacency. Furthermore, it SHOULD be incremented
linearly for each new message of the given type, cycling back to 1
after running the full range. For event messages, the Transaction ID
SHOULD be set to zero.
Unless otherwise specified, the default behaviour for all ANCP
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responses is that the value of the Transaction ID MUST be copied from
the corresponding request message.
3.6.1.7. I flag and SubMessage Number
In GSMPv3 these provide a mechanism for message fragmentation.
Because ANCP uses TCP transport, this mechanism is unnecessary. An
ANCP agent SHOULD set the I Flag and subMessage Number fields to 1 to
signify "no fragmentation".
3.6.1.8. Length
This field MUST be set to the length of the ANCP message in bytes,
including its header fields and message body but excluding the four-
byte encapsulating header defined in Section 3.2.
3.6.2. The ANCP Message Body
The detailed contents of the message payload portion of a given ANCP
message can vary with the capability in the context of which it is
being used. However, the general format consists of zero or more
fixed fields, followed by a variable amount of data in the form of
Type-Length-Value (TLV) data structures.
The general format of a TLV is shown in Figure 7:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type (IANA registered) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Value ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: General TLV Format
The fields of a TLV are defined as follows:
Type: The TLV Type is a 16-bit unsigned value identifying the TLV
type and nature of its contents. An IANA registry has been
established for ANCP TLV Type codes.
Length: The number of bytes of data in the Value field of the TLV,
excluding any padding required to bring this TLV to a 4-byte word
boundary (see "Value" below). If a TLV contains other TLVs, any
padding in the contained TLVs MUST be included in the value of
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Length. Depending on the specification of the TLV, the value of
Length can be zero, a constant for all instances of the TLV, or a
varying quantity.
Value: The actual data carried by the TLV, if any. The value field
in each TLV MUST be padded with zeroes as required to align with a
4-byte word boundary. The Value field of a TLV MAY include fixed
fields and/or other TLVs.
Unless otherwise specified, TLVs MAY be added to a message in any
order. If the recipient of a message does not understand a
particular TLV, it MUST silently ignore it.
A number of TLVs are specified in the remainder of this document.
3.7. General Principles for the Design of ANCP Messages
The GSMPv3 protocol [RFC3292] allows for two messaging constructs to
support request/response interaction:
a. The same message type is used for both the request message and
the response message. The Result and Code field settings are
used to differentiate between request and response messages.
b. The request and response messages use two different message
types.
The first approach is illustrated by the protocol specifications in
Section 8.4, the second by specifications in Section 6.4. The
purpose of this section is to provide more details about the second
approach in order to allow the use of this messaging construct for
the development of additional ANCP extensions.
As Section 3.6 indicated, all ANCP messages other than adjacency
messages share a common header format. When the response message
type is different from that of the request, the specification of the
request message will typically indicate that the Result field is set
to Ignore (0x0) and provide procedures indicating explicitly when the
receiver should generate a response and what message type it should
use.
The Transaction ID field is used to distinguish between multiple
request messages of the same type and to associate a response message
to a request. Specifications of ANCP messages for applications not
requiring response correlation SHOULD indicate that the Transaction
ID MUST be set to zero in requests. Applications that require
response correlation SHOULD refer to the Transaction ID behaviour
described in Section 3.6.1.
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The specification for a response message SHOULD indicate in all cases
that value of the Transaction Identifier MUST be set to that of the
corresponding request message. This allows the requester to
establish whether or not correlation is needed (by setting a non-zero
or zero value for the Transaction ID).
4. Generally Useful ANCP Messages and TLVs
This section defines two messages and a number of TLVs that could be
useful in multiple capabilities. In some cases the content is under-
specified, with the intention that particular capabilities spell out
the remaining details.
4.1. Provisioning Message
The Provisioning message is sent by the NAS to the AN to provision
information of global scope (i.e., not associated with specific
access lines) on the AN. The Provisioning message has the format
shown in Figure 8. Support of the Provisioning message is OPTIONAL
unless the ANCP agent claims support for a capability that requires
its use.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TCP/IP Encapsulating Header (Section 3.2) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ANCP General Message Header |
+ (Section 3.6.1) +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ TLVs ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8: Format of the Provisioning Message
The message header field settings given below are REQUIRED in the
Provisioning message. The remaining message header fields MUST be
set as specified in Section 3.6.1. Which TLVs to carry in the
Provisioning message is specified as part of the specification of the
capabilities that use that message. The Provisioning message MAY be
used to carry data relating to more than one capability at once,
assuming that the capabilities concerned can co-exist and have all
been negotiated during adjacency establishment.
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Message Type: MUST be set to 93.
Result: MUST be set to 0x0 (Ignore).
Code: MUST be set to zero.
Transaction ID: MUST be populated with a non-zero value chosen in
the manner described in Section 3.6.1.6.
If the AN can process the message successfully and accept all the
provisioning directives contained in it, the AN MUST NOT send any
response.
Unless otherwise specified for a particular capability, if the AN
fails to process the message successfully it MUST send a Generic
Response message (Section 4.2) indicating failure and providing
appropriate diagnostic information.
4.2. Generic Response Message
This section defines the Generic Response message. The Generic
Response message MAY be specified as the appropriate response to a
message defined in an extension to ANCP, instead of a more specific
response message. As a general guideline, specification of the
Generic Response message as a response is appropriate where no data
needs to be returned to the peer other than a result (success or
failure), plus, in the case of a failure, a code indicating the
reason for failure and a limited amount of diagnostic data.
Depending on the particular use case, the Generic Response message
MAY be sent by either the NAS or the AN.
Support of the Generic Response message, both as sender and as
receiver, is REQUIRED for all ANCP agents, regardless of what
capabilities they support.
The AN or NAS MAY send a Generic Response message indicating a
failure condition independently of a specific request before closing
the adjacency as a consequence of that failure condition. In this
case, the sender MUST set the Transaction ID field in the header and
the Message Type field within the Status-Info TLV to zeroes. The
receiver MAY record the information contained in the Status-Info TLV
for management use.
The format of the Generic Response message is shown in Figure 9
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TCP/IP Encapsulating Header (Section 3.2) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ANCP General Message Header |
+ (Section 3.6.1) +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Access line identifying TLV(s) |
+ (copied from original request) +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Status-Info TLV |
~ (Section 4.5) ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
NOTE: TLVs MAY be in a different order from what is shown in this
figure.
Figure 9: Structure of the Generic Response Message
This document specifies the following header fields. The remaining
fields in the ANCP general message header MUST be set as specified in
Section 3.6.1.
Message Type: MUST be set to 91.
Result: MUST be set to 0x3 (Success) or 0x4 (Failure).
Code: MUST be set to zero for success or an appropriate non-zero
value for failure.
Transaction ID: MUST be copied from the message to which this
message is a response.
If the original request applied to a specific access line or set of
lines, the TLVs identifying the line(s) and possibly the user MUST be
copied into the Generic Response message at the top level.
The Status-Info TLV MAY be present in a success response, to provide
a warning as defined for a specific request message type. It MUST be
present in a failure response. See Section 4.5 for a detailed
description of the Status-Info TLV. The actual contents will depend
on the request message type this message is responding to and the
value of the Code field.
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To prevent an infinite loop of error responses, if the Generic
Response message is itself in error, the receiver MUST NOT generate
an error response in return.
4.3. Target TLV
Type: 0x1000 to 0x1020 depending on the specific content. Only
0x1000 has been assigned in this specification (see below).
Support of any specific variant of the Target TLV is OPTIONAL
unless the ANCP agent claims support for a capability that
requires its use.
Description: The Target TLV (0x1000 - 0x1020) is intended to be a
general means to represent different types of objects.
Length: Variable, depending on the specific object type.
Value: Target information as defined for each object type. The
Value field MAY consist of sub-TLVs.
TLV Type 0x1000 is assigned to a variant of the Target TLV
representing a single access line and encapsulating one or more sub-
TLVs identifying the target. Figure 10 is an example illustrating
the TLV format for a single port identified by an Access-Loop-
Circuit-ID TLV (0x0001) (Section 5.1.2.1).
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Type = 0x1000 |Length = Circuit-ID Length + 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Access-Loop-Circuit-ID=0x0001 | Circuit-ID Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Access Loop Circuit ID ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 10: Example of Target TLV For Single Access Line
4.4. Command TLV
Type: 0x0011
Description: The Command TLV (0x0011) is intended to be a general
means of encapsulating one or more command directives in a TLV
oriented message. The semantics of the command can be specified
for each message type using it. I.e., the specification of each
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message type that can carry the Command TLV is expected to define
the meaning of the content of the payload, although re-use of
specifications is, of course, permissible when appropriate.
Support of any specific variant of the Command TLV is OPTIONAL
unless the ANCP agent claims support for a capability that
requires its use.
Length: Variable, depending on the specific contents.
Value: Command information as defined for each message type. The
field MAY include sub-TLVs. The contents of this TLV MUST be
specified as one "command" or alternatively a sequence of one or
more "commands", each beginning with a one-byte Command Code and
possibly including other data following the Command Code. An IANA
registry has been established for Command Code values. This
document reserves the Command Code value 0 as an initial entry in
the registry.
4.5. Status-Info TLV
Name: Status-Info
Type: 0x0106
Description: The Status-Info-TLV is intended to be a general
container for warning or error diagnostics relating to commands
and/or requests. It is a supplement to the Code field in the ANCP
general header. The specifications for individual message types
MAY indicate the use of this TLV as part of responses,
particularly for failures. As mentioned above, the Generic
Response message will usually include an instance of the Status-
Info TLV. Support of the Status-Info TLV, both as sender and as
receiver, is REQUIRED for all ANCP agents, regardless of what
capabilities they support.
Length: Variable, depending on the specific contents.
Value: The following fixed fields. In addition, sub-TLVs MAY be
appended to provide further diagnostic information.
Reserved (one byte): see Section 3.4 for handling of reserved
fields.
Msg Type: Message Type of the request for which this TLV is
providing diagnostics.
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Error Message Length: Number of bytes in the error message,
excluding padding. This MAY be zero if no error message is
provided.
Error Message: Human-readable string providing information about
the warning or error condition. Padded with zeroes as
necessary to extend to a four-byte word boundary.
Section 3.6.1.4 provides recommendations for what TLVs to add in
the Status-Info TLV for particular values of the message header
Code field.
Figure 11 illustrates the Status-Info TLV.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Type = 0x0106 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Msg Type | Error Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Error Message (padded to 4 byte boundary) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| optional sub-TLVs... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 11: The Status-Info TLV
5. Introduction To ANCP Capabilities For Digital Subscriber Lines (DSL)
DSL is a widely deployed access technology for Broadband Access for
Next Generation Networks. Specifications such as [TR-059], [TR-058],
and [TR-092] describe possible architectures for these access
networks. The scope of these specifications includes the delivery of
voice, video, and data services.
The next three sections of this document specify basic ANCP
capabilities for use specifically in controlling Access Nodes serving
DSL access (Tech Type = 0x05). The same ANs could be serving other
access technologies (e.g. Metro-Ethernet, Passive Optical
Networking, WiMax), in which case the AN will also have to support
the corresponding other-technology-specific capabilities. Those
additional capabilities are outside the scope of the present
document.
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5.1. DSL Access Line Identification
Most ANCP messages involve actions relating to a specific access
line. Thus it is necessary to describe how access lines are
identified within those messages. This section defines four TLVs for
that purpose and provides an informative description of how they are
used.
5.1.1. Control Context (Informative)
Three types of identification are described in [TR-101] and provided
for in the TLVs defined in this section:
o identification of an access line by its logical appearance on the
user side of the Access Node;
o identification of an access line by its logical appearance on the
NAS side of the Access Node; and
o identification down to the user or host level as a supplement to
access line identification in one of the other two forms.
All of these identifiers originate with the AN control application,
during the process of DSL topology discovery. The control
application chooses which identifiers to use and the values to place
into them on a line-by-line basis, based on AN configuration and
deployment considerations.
Aside from its use in ANCP signalling, access line identification is
also used in DHCP transactions involving hosts served by DSL. Either
the AN or the NAS can serve as a DHCP relay node. [TR-101] requires
the AN or NAS in this role to add access line identification in
Option 82 (Information) to each DHCP request it forwards to the DHCP
server. It is desirable for efficiency that the identification used
in this signalling should be the same as the identification used in
ANCP messages.
From the point of view of ANCP itself, the identifiers are opaque.
From the point of view of the AN control application, the syntax for
the user-side access line identifier is the same as specified in
Section 3.9.3 of [TR-101] for DHCP Option 82. The syntax for the
ASCII form of the NAS-side access line identifier will be similar.
Access line identification by logical appearance on the user side of
the Access Node will always identify a DSL loop uniquely.
Identification by the logical appearance on the NAS side of the
Access Node is unique only if there is a one-to-one mapping between
the appearances on the two sides and no identity-modifying
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aggregation between the AN and the NAS. In other cases, and in
particular in the case of Ethernet aggregation using the N:1 VLAN
model, the user-side access line identification is necessary, but the
NAS-side identification is potentially useful information allowing
the NAS to build up a picture of the aggregation network topology.
Additional identification down to the user or host level is intended
to supplement rather than replace either of the other two forms of
identification.
Sections 3.8 and 3.9 of [TR-101] are contradictory on this point.
It is assumed here that Section 3.9 is meant to be authoritative.
The user-level identification takes the form of an administered
string which again is opaque at the ANCP level.
The NAS control application will use the identifying information it
receives from the AN directly for some purposes. For examples, see
the introductory part of Section 3.9 of [TR-101]. For other
purposes, the NAS will build a mapping between the unique access line
identification provided by the AN, the additional identification of
the user or host (where provided), and the IP interface on a
particular host. For access lines with static IP address assignment
that mapping could be configured instead.
5.1.2. TLVs For DSL Access Line Identification
This section provides a normative specification of the TLVs that ANCP
provides to carry the types of identification just described. The
Access-Loop-Circuit-ID TLV identifies an access line by its logical
appearance on the user side of the Access Node. Two alternatives,
the Access-Aggregation-Circuit-ID-ASCII TLV and the Access-
Aggregation-Circuit-ID-Binary TLV, identify an access line by its
logical appearance on the NAS side of the Access Node. It is
unlikely that a given AN uses both of these TLVs, either for the same
line or for different lines, since they carry equivalent information.
Finally, the Access-Loop-Remote-Id TLV contains an operator-
configured string that uniquely identifies the user on the associated
access line, as described in Sections 3.9.1 and 3.9.2 of [TR-101].
As normative requirements on ANCP agents conforming to this section:
o ANCP agents MUST be able to build and send the Access-Loop-
Circuit-ID TLV, the Access-Loop-Remote-Id TLV, and either the
Access-Aggregation-Circuit-ID-ASCII TLV or the Access-Aggregation-
Circuit-ID-Binary TLV (implementation choice), when passed the
associated information from the AN control application.
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o ANCP agents MUST be able to receive all four TLV types, extract
the relevant information, and pass it to the control application.
o If the Access-Loop-Remote-Id TLV is present in a message, it MUST
be accompanied by an Access-Loop-Circuit-ID TLV and/or an Access-
Aggregation-Circuit-ID-xxx TLV with two VLAN identifiers.
The Access-Loop-Remote-Id TLV is not enough to identify an
access line uniquely on its own. As indicated above, an
Access-Aggregation-Circuit-ID-xxx TLV with two VLAN identifiers
may or may not identify an access line uniquely, but this is up
to the control application to decide.
o If the Access-Aggregation-Circuit-ID-xxx TLV is present in a
message with just one VLAN identifier, it MUST be accompanied by
an Access-Loop-Circuit-ID TLV.
5.1.2.1. Access-Loop-Circuit-ID TLV
Type: 0x0001
Description: a locally administered human-readable string generated
by or configured on the Access Node, identifying the corresponding
access loop logical port on the user side of the Access Node.
Length: up to 63 bytes
Value: ASCII string
5.1.2.2. Access-Loop-Remote-Id TLV
Type: 0x0002
Description: an operator-configured string that uniquely identifies
the user on the associated access line, as described in Sections
3.9.1 and 3.9.2 of [TR-101].
Length: up to 63 bytes
Value: ASCII string
5.1.2.3. Access-Aggregation-Circuit-ID-Binary TLV
Type: 0x0006
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Description: This TLV identifies or partially identifies a specific
access line by means of its logical circuit identifier on the NAS
side of the Access Node.
For Ethernet access aggregation, where a per-subscriber (stacked)
VLAN can be applied (1:1 model as defined in [TR-101]), the TLV
contains two value fields. Each field carries a 12-bit VLAN
identifier (which is part of the VLAN tag defined by IEEE 802.1Q).
The first field MUST carry the inner VLAN identifier, while the
second field MUST carry the outer VLAN identifier.
When the N:1 VLAN model is used, only one VLAN tag is available.
For the N:1 model, the Access-Aggregation-Circuit-ID-Binary TLV
contains a single value field, which MUST carry the 12-bit VLAN
identifier derived from the single available VLAN tag.
In the case of an ATM aggregation network, where the DSLAM is
directly connected to the NAS (without an intermediate ATM
switch), the VPI and VCI on the DSLAM uplink correspond uniquely
to the DSL line on the DSLAM. The Access-Aggregation-Circuit-ID-
Binary TLV MAY be used to carry the VPI and VCI. The first value
field of the TLV MUST carry the VCI, while the second value field
MUST carry the VPI.
Each identifier MUST be placed in the low-order bits of its
respective 32-bit field, with the higher-order bits set to zero.
The ordering of the bits of the identifer MUST be the same as when
the identifier is transmitted on the wire to identify an Ethernet
frame or ATM cell.
The Access-Aggregation-Circuit-ID-Binary is illustrated in
Figure 12.
Length: 4 or 8 bytes
Value: one or two 32-bit binary fields.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Type = 0x0006 | Length = 4 or 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Single VLAN Identifier, inner VLAN identifier, or VCI |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Outer VLAN identifier or VPI |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Figure 12: The Access-Aggregation-Circuit-ID-Binary TLV
5.1.2.4. Access-Aggregation-Circuit-ID-ASCII TLV
Type: 0x0003
Description: This TLV transmits the ASCII equivalent of the Access-
Aggregation-Circuit-ID-Binary TLV. As mentioned in the previous
section, the AN control application will use a format similar to
that specified in Section 3.9.3 of [TR-101] for the format of the
"circuit-id".
As an extension to the present document, the Access Node could
convey to the NAS the characteristics (e.g., bandwidth) of the
uplink on the Access Node. This TLV or the binary equivalent
defined above then serves the purpose of uniquely identifying the
uplink whose characteristics are being defined. The present
document does not specify the TLVs needed to convey the uplink
characteristics.
Length: up to 63 bytes
Value: ASCII string
6. ANCP Based DSL Topology Discovery
Section 3.1 of [RFC5851] describes the requirements for the DSL
Topology Discovery capability.
6.1. Control Context (Informative)
The AN control application in the DSLAM requests ANCP to send a DSL-
specific Port Up message to the NAS under the following
circumstances:
o when a new adjacency with the NAS is established, for each DSL
loop that is synchronized at that time;
o subsequent to that, whenever a DSL loop resynchronizes; and
o whenever the AN control application wishes to signal that a line
attribute has changed.
The AN control application in the DSLAM requests ANCP to send a DSL-
specific Port Down message to the NAS under the following
circumstances:
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o when a new adjacency with the NAS is established, for each DSL
loop that is provisioned but not synchronized at that time;
o whenever a DSL loop that is equipped in an AN but administratively
disabled is signalled as "IDLE"; and
o subsequent to that, whenever a DSL loop loses synchronization.
The AN control application passes information to identify the DSL
loop to ANCP to include in the Port Up or Port Down message, along
with information relating to DSL loop attributes.
In the case of bonded copper loops to the customer premise (as per
DSL multi-pair bonding described by [G.988.1] and [G.988.2]), the AN
control application requests that ANCP send DSL-specific Port Up and
Port Down messages for the aggregate "DSL bonded circuit"
(represented as a single logical port) as well as the individual DSL
loops of which it is comprised. The information relating to DSL line
attributes that is passed by the AN control application is aggregate
information.
ANCP generates the DSL-specific Port Up or Port Down message and
transfers it to the NAS. ANCP on the NAS side passes an indication
to the NAS control application that a DSL Port Up or Port Down
message has been received along with the information contained in the
message.
The NAS control application updates its view of the DSL loop state,
performs any required accounting operations, and uses any included
line attributes to adjust the operation of its queueing/scheduling
mechanisms as they apply to data passing to and from that DSL loop.
Figure 13 summarizes the interaction.
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1. Home Access NAS
Gateway Node
-----------> -------------------------->
DSL Port Up (Event message)
Signal (default line parameters)
2. Home Access NAS
Gateway Node
-----------> -------------------------->
DSL Port Up (Event message)
Resynch (updated line parameters)
3. Home Access NAS
Gateway Node
-----------> -------------------------->
Loss of Port Down (Event message)
DSL Signal (selected line parameters)
Figure 13: ANCP Message Flow For DSL Topology Discovery
6.2. Protocol Requirements
The DSL topology discovery capability is assigned capability type
0x0001. No capability data is associated with this capability.
6.2.1. Protocol Requirements On the AN Side
The AN-side ANCP agent MUST be able to create DSL-specific Port Up
and Port Down messages according to the format specified in
Section 6.3.
The AN-side ANCP agent MUST conform to the normative requirements of
Section 5.1.2.
The AN-side ANCP agent "must" be able to accept any information
passed to it by the AN control application that can validly be
included in any of the line attribute TLVs specified in Section 6.5,
MUST package that information as TLVs, and MUST include these TLVs,
encapsulated in the DSL-Line-Attributes TLV, within the Port Up or
Port Down message.
The AN-side ANCP agent MUST follow the AN-side procedures associated
with DSL-specific Port Up and Port Down messages as they are
specified in Section 6.4.
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6.2.2. Protocol Requirements On the NAS Side
The NAS-side ANCP agent MUST be able to receive and validate DSL-
specific Port Up and Port Down messages according to the format
specified in Section 6.3.
The NAS-side ANCP agent MUST conform to the normative requirements of
Section 5.1.2.
The NAS-side ANCP agent MUST follow the NAS-side procedures
associated with DSL-specific Port Up and Port Down messages as they
are specified in Section 6.4.
The NAS-side ANCP agent MUST be able to extract the information
contained in any of the TLVs specified in Section 6.5 and "must" be
able to make that information available to the NAS control
application.
6.3. ANCP Port UP and Port DOWN Event Message Descriptions
The ANCP Port UP and Port DOWN Event messages are derived from the
GSMPv3 Event message shown in Section 9 of [RFC3292]. The modified
format used for DSL topology discovery is shown in Figure 14.
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TCP/IP Encapsulating Header (Section 3.2) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ANCP General Message Header |
+ (Section 3.6.1) +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Port (unused) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Port Session Number (unused) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Event Sequence Number (unused) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+--- Label (8 bytes, unused) ---+
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|x|x|x|x|x|x|x|x| Message Type | Tech Type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| # of TLVs | Extension Block length (bytes)|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Access line identifying TLV(s) ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DSL-Line-Attributes TLV |
~ (MANDATORY in Port Up, OPTIONAL in Port Down) ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
NOTE: TLVs MAY be in a different order from what is shown in this
figure.
Figure 14: Format Of the ANCP Port Up and Port Down Event Messages
For DSL Topology Discovery
See Section 3.6.1 for a description of the ANCP general message
header. The Message Type field MUST be set to 80 for Port Up, 81 for
Port Down. The 12 bit Code field MUST be set to 0. The 4 bit Result
field MUST be set to 0 (signifying Ignore). The 24-bit Transaction
Identifier field MUST be set to 0. Other fields in the general
header MUST be set as described in Section 3.6.
The Port, Port Session Number, and Event Sequence Number fields are
not used by the DSL Topology Discovery capability. The Label field
(including the Stacked Label Indicator and the unused flags at the
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start of the Label field), is also unused, and MUST be treated as an
unused fixed 8-byte field. The handling of unused/reserved fields is
described in Section 3.4.
The remaining message fields belong to the "extension block" added to
the original GSMPv3 message by ANCP, and are described as follows:
Extension Flags: The flag bits denoted by 'x' are currently
unspecified and reserved.
Message Type: Message Type has the same value as in the general
header (i.e., 80 or 81).
Tech Type: MUST be set to 0x05 (DSL).
# of TLVs: the number of TLVs that follow, not counting TLVs
encapsulated within other TLVs.
Extension Block Length: the total length of the TLVs carried in the
extension block in bytes, including any padding within individual
TLVs.
TLVs: one or more TLVs to identify a DSL line and zero or more TLVs
to define its characteristics.
6.4. Procedures
6.4.1. Procedures On the AN Side
The AN-side ANCP agent MUST create and transmit a DSL-specific Port
Up or Port Down message when requested by the AN control application
and presented with the information needed to build a valid message,
except if transmission is inhibited by a rate-dampening mechanism.
It is RECOMMENDED that the Access Node use a dampening mechanism per
DSL loop to control the rate at which state changes are communicated
to the NAS.
At the top level, the extension block within a DSL-specific Port Up
or Port Down message MUST include TLVs from Section 5.1.2 to identify
the DSL loop.
TLVs presenting DSL line attributes (i.e., the TLVs specified in
Section 6.5) MUST be encapsulated within the DSL-Line-Attributes TLV.
When the DSL-Line-Attributes TLV is present in a message, it MUST
contain at least one such TLV and will generally contain more than
one. In the Port Up message, the DSL-Line-Attributes TLV MUST be
present. In the Port Down message, the DSL-Line-Attributes TLV MAY
be present.
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If the AN-side ANCP agent is unable to satisfy a request from the AN
control application because it detects an error in the request or
because it receives a Generic Response message indicating an error in
a Port Up or Port Down message that it has sent and is unable to
recover from that error at the protocol level, it "must" inform the
application, including any available diagnostic information.
6.4.2. Procedures On the NAS Side
The NAS-side ANCP agent MUST be prepared to receive Port Up and Port
Down messages for a given DSL loop or logical port at any time after
negotiation of an adjacency has been completed. It is possible for
two Port Up messages in succession to be received for the same DSL
loop without an intervening Port Down message, and vice versa.
The NAS-side ANCP agent SHOULD validate each message against the
specifications given in Section 6.3 and the TLV specifications given
in Section 5.1.2 and Section 6.5. If it finds an error it MAY
generate a Generic Response message containing an appropriate Result
Code value. If it does so, the message MUST contain copies of all of
the identifier TLVs from Section 5.1.2 that were present in the Port
Up or Port Down message. The message SHOULD also contain a Status-
Info TLV which in turn contains other information appropriate to the
message header Code value as described in Section 3.6.1.4.
If the received message passes validation, the NAS-side ANCP agent
"must" extract the information from the TLVs contained in the message
and present that information along with an indication of reported
event type to the NAS control application. If validation of
individual TLVs fails but the message as a whole can be processed,
the NAS-side ANCP agent "may" pass the valid message contents to the
NAS control application.
6.5. TLVs For DSL Line Attributes
As specified above, the DSL-Line-Attributes TLV is inserted into the
Port Up or Port Down message at the top level. The remaining TLVs
defined below are encapsulated within the DSL-Line-Attributes TLV.
6.5.1. DSL-Line-Attributes TLV
Type: 0x0004
Description: This TLV encapsulates attribute values for a DSL line
serving a subscriber.
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Length: variable (up to 1024 bytes)
Value: one or more encapsulated TLVs corresponding to DSL line
attributes. The DSL-Line-Attributes TLV MUST contain at least one
TLV when it is present in a Port Up or Port Down message. The
actual contents are determined by the AN control application.
6.5.2. DSL-Type TLV
Type: 0x0091
Description: Indicates the type of transmission system in use.
Length: 4 bytes
Value: 32 bit unsigned integer
ADSL1 = 1
ADSL2 = 2
ADSL2+ = 3
VDSL1 = 4
VDSL2 = 5
SDSL = 6
OTHER = 0
6.5.3. Actual-Net-Data-Rate-Upstream TLV
Type: 0x0081
Description: Actual upstream net data rate on a DSL line.
Length: 4 bytes
Value: Rate in Kbits/s as a 32 bit unsigned integer
6.5.4. Actual-Net-Data-Rate-Downstream TLV
Type: 0x0082
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Description: Actual downstream net data rate on a DSL line.
Length: 4 bytes
Value: Rate in Kbits/s as a 32 bit unsigned integer
6.5.5. Minimum-Net-Data-Rate-Upstream TLV
Type: 0x0083
Description: Minimum upstream net data rate desired by the operator.
Length: 4 bytes
Value: Rate in Kbits/s as a 32 bit unsigned integer
6.5.6. Minimum-Net-Data-Rate-Downstream TLV
Type: 0x0084
Description: Minimum downstream net data rate desired by the
operator.
Length: 4 bytes
Value: Rate in Kbits/s as a 32 bit unsigned integer
6.5.7. Attainable-Net-Data-Rate-Upstream TLV
Type: 0x0085
Description: Maximum net upstream rate that can be attained on the
DSL line.
Length: 4 bytes
Value: Rate in Kbits/s as a 32 bit unsigned integer
6.5.8. Attainable-Net-Data-Rate-Downstream TLV
Type: 0x0086
Description: Maximum net downstream rate that can be attained on the
DSL line.
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Length: 4 bytes
Value: Rate in Kbits/s as a 32 bit unsigned integer
6.5.9. Maximum-Net-Data-Rate-Upstream TLV
Type: 0x0087
Description: Maximum net upstream data rate desired by the operator.
Length: 4 bytes
Value: Rate in Kbits/s as a 32 bit unsigned integer
6.5.10. Maximum-Net-Data-Rate-Downstream TLV
Type: 0x0088
Description: Maximum net downstream data rate desired by the
operator.
Length: 4 bytes
Value: Rate in Kbits/s as a 32 bit unsigned integer
6.5.11. Minimum-Net-Low-Power-Data-Rate-Upstream TLV
Type: 0x0089
Description: Minimum net upstream data rate desired by the operator
in low power state.
Length: 4 bytes
Value: Rate in Kbits/s as a 32 bit unsigned integer
6.5.12. Minimum-Net-Low-Power-Data-Rate-Downstream TLV
Type: 0x008A
Description: Minimum net downstream data rate desired by the
operator in low power state.
Length: 4 bytes
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Value: Rate in Kbits/s as a 32 bit unsigned integer
6.5.13. Maximum-Interleaving-Delay-Upstream TLV
Type: 0x008B
Description: maximum one way interleaving delay.
Length: 4 bytes
Value: Time in ms as a 32 bit unsigned integer
6.5.14. Actual-Interleaving-Delay-Upstream TLV
Type: 0x008C
Description: Value corresponding to the interleaver setting.
Length: 4 bytes
Value: Time in ms as a 32 bit unsigned integer
6.5.15. Maximum-Interleaving-Delay-Downstream TLV
Type: 0x008D
Description: maximum one way interleaving delay.
Length: 4 bytes
Value: Time in ms as a 32 bit unsigned integer
6.5.16. Actual-Interleaving-Delay-Downstream
Type: 0x008E
Description: Value corresponding to the interleaver setting.
Length: 4 bytes
Value: Time in ms as a 32 bit unsigned integer
6.5.17. DSL-Line-State TLV
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Type: 0x008F
Description: The state of the DSL line.
Length: 4 bytes
Value: 32 bit unsigned integer
SHOWTIME = 1
IDLE = 2
SILENT = 3
6.5.18. Access-Loop-Encapsulation TLV
Type: 0x0090
Description: The data link protocol and, optionally, the
encapsulation overhead on the access loop. When this TLV is
present, at least the data link protocol MUST be indicated. The
encapsulation overhead MAY be indicated. The Access Node MAY
choose to not convey the encapsulation on the access loop by
specifying values of 0 (NA) for the two encapsulation fields.
Length: 3 bytes
Value: The three bytes (most to least significant) and valid set of
values for each byte are defined as follows:
Byte 1: Data Link
ATM AAL5 = 0
ETHERNET = 1
Byte 2: Encapsulation 1
NA = 0
Untagged Ethernet = 1
Single-tagged Ethernet = 2
Double-tagged Ethernet = 3
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Byte 3: Encapsulation 2
NA = 0
PPPoA LLC = 1
PPPoA NULL = 2
IPoA LLC = 3
IPoA NuLL = 4
Ethernet over AAL5 LLC with FCS = 5
Ethernet over AAL5 LLC without FCS = 6
Ethernet over AAL5 NULL with FCS = 7
Ethernet over AAL5 NULL without FCS = 8
The Access-Loop-Encapsulation TLV is illustrated in Figure 15.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Type = 0x0090 | Length = 3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data link | Encaps 1 | Encaps 2 | Padding (=0) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 15: The Access-Loop-Encapsulation TLV
7. ANCP based DSL Line Configuration
The use case for ANCP-based DSL Line Configuration is described in
Section 3.2 of [RFC5851].
7.1. Control Context (Informative)
Triggered by topology information reporting a new DSL line or
triggered by a subsequent user session establishment (PPP or DHCP),
RADIUS/AAA sends service parameters to the NAS control application
for configuration on the access line. The NAS control application
passes the request on to the NAS-side agent, which sends the
information to the AN by means of a Port Management (line
configuration) message. The AN-side agent passes this information up
to the AN control application, which applies it to the line.
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Figure 16 summarizes the interaction.
Home Access NAS RADIUS/AAA
Gateway Node Policy Server
-----------> --------------->
DSL Port Up message)
Signal (line parameters)
--------------------------------> -------------->
PPP/DHCP Session Authentication &
authorization
<----------------
Port Management message
(line configuration)
Figure 16: Message Flow - ANCP Mapping For Initial Line Configuration
The NAS could update the line configuration as a result of a
subscriber service change (e.g. triggered by the policy server).
Figure 17 summarizes the interaction.
User Home Access NAS
Gateway Node
-------------------------->
PPP/DHCP Session
-------------------------------------------------------> Web portal,
Service on demand OSS, etc.
|
<-------------- RADIUS/AAA
Change of Policy Server
authorization
<------------
Port Management
message
(new profile)
Figure 17: Message flow - ANCP Mapping For Updated Line Configuration
7.2. Protocol Requirements
The DSL line configuration capability is assigned capability type
0x0002. No capability data is associated with this capability.
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7.2.1. Protocol Requirements On the NAS Side
The NAS-side ANCP agent MUST be able to create DSL-specific Port
Management (line configuration) messages according to the format
specified in Section 7.3.
The NAS-side ANCP agent MUST conform to the normative requirements of
Section 5.1.2.
The NAS-side ANCP agent "must" be able to accept any information
passed to it by the NAS control application that may validly be
included in any of the TLVs specified in Section 7.5.
In the current version of this specification only one such TLV is
defined.
The NAS-side ANCP agent MUST package that information as TLVs, and
MUST include these TLVs within the Port Management (line
configuration) message.
The NAS-side ANCP agent MUST follow the NAS-side procedures
associated with DSL-specific Port Management (line configuration)
messages as they are specified in Section 7.4.
7.2.2. Protocol Requirements On the AN Side
The AN-side ANCP agent MUST conform to the normative requirements of
Section 5.1.2.
The AN-side ANCP agent MUST be able to receive and validate DSL-
specific Port Management (line configuration) messages according to
the format specified in Section 7.3.
The AN-side ANCP agent MUST follow the AN-side procedures associated
with DSL-specific Port Management (line configuration) messages as
specified in Section 7.4.
The NAS-side ANCP agent MUST be able to extract the information
contained in any of the TLVs listed in Section 7.2.1 and "must" make
that information available to the NAS control application.
7.3. ANCP Port Management (Line Configuration) Message Format
The ANCP Port Management message for DSL line configuration has the
format shown in Figure 18.
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TCP/IP Encapsulating Header (Section 3.2) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ANCP General Message Header |
+ (Section 3.6.1) +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Port (unused) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Port Session Number (unused) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Event Sequence Number (unused) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R|x|x|x|x|x|x|x| Dur. (unused) | Function=8 | X-Function=0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Event Flags (unused) | Flow Control Flags (unused) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|x|x|x|x|x|x|x|x| Message Type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| # of TLVs | Extension Block length (bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Access line identifying TLV(s) ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Line configuration TLV(s) ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
NOTE: TLVs MAY be in a different order from what is shown in this
figure.
Figure 18: Port Management Message For DSL Line Configuration
See Section 3.6 for a description of the ANCP general message header.
The Message Type field MUST be set to 32. The 12 bit Code field MUST
be set to 0. The 4 bit Result field MUST be set to either 1 (NAck)
or 2 (AckAll), as determined by policy on the NAS. The 24-bit
Transaction Identifier field MUST be set to a positive value. Other
fields in the general header MUST be set as described in Section 3.6.
As with the Port Up and Port Down messages described above, the Port
Management message format defined in [RFC3292] has been modified to
contain additional data in an "extension block" at the end of the
message. Also, the original two byte Function field has been
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modified to contain one byte for the Function field indicating a
specific action to be taken by the recipient of the message, and one
byte for X-Function field, which further qualifies the action
specified in the Function field. Any Function specific data MUST be
carried in TLVs in the extension block.
The Port, Port Session Number, and Event Sequence Number fields are
not used by the DSL Line Configuration capability. The handling of
unused/reserved fields is described in Section 3.4.
The remaining message fields are described as follows:
R Flag: not used by ANCP.
Additional Port Management flags: the flag bits marked 'x' following
the R flag are not used by ANCP.
Duration: not used for DSL line configuration.
Function: action to be performed. For line configuration, Function
MUST be set to 8 (Configure Connection Service Data). This action
type requests the Access Node (i.e., DSLAM) to apply service
configuration data contained in the line configuration TLVs to the
DSL line designated by the access line identifying TLVs.
X-Function: qualifies the action set by Function. For DSL line
configuration, this field MUST be set to 0.
Event Flags: not used by ANCP.
Flow Control Flags: not used by ANCP.
Extension Flags: the flag bits denoted by 'x' before the Message
Type field are reserved for future use.
Message Type: Message Type has the same value as in the general
header (i.e., 32).
Reserved (16 bits): reserved for future use.
# of TLVs: the number of TLVs that follow, not counting TLVs
encapsulated within other TLVs.
Extension Block Length: the total length of the TLVs carried in the
extension block in bytes, including any padding within individual
TLVs.
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TLVs: two or more TLVs to identify a DSL line and configure its
service data.
Other ANCP capabilities, either specific to DSL or technology-
independent, MAY reuse the Port Management message for service
configuration. If the settings of the fixed fields are compatible
with the settings just described, the same Port Management message
that is used for DSL line configuration MAY be used to carry TLVs
relating to the other capabilities that apply to the same DSL loop.
Use of the Port Management message for configuration MAY also be
generalized to other access technologies, if the respective
capabilities specify use of access line identifiers appropriate to
those technologies in place of the identifiers defined in
Section 5.1.2.
7.4. Procedures
Service configuration MAY be performed on an access line regardless
of its current state.
7.4.1. Procedures On the NAS Side
When requested by the NAS control application and presented with the
necessary information to do so, the NAS-side agent MUST create and
send a Port Management message with the fixed fields set as described
in the previous section. The message MUST contain one or more TLVs
to identify an access line according the requirements of
Section 5.1.2. The NAS MUST include one or more TLVs to configure
line service parameters for that line. Section 7.5 currently
identifies only one such TLV, Service-Profile-Name, but other TLVs
MAY be added by extensions to ANCP.
7.4.2. Procedures On the AN Side
The AN-side ANCP agent MUST be prepared to receive Port Management
(line configuration) messages for a given DSL loop or logical port at
any time after negotiation of an adjacency has been completed.
The AN-side ANCP agent SHOULD validate each message against the
specifications given in Section 7.3 and the TLV specifications given
in Section 5.1.2 and Section 7.5. If it finds an error it MUST
return a Port Management response message which copies the Port
Management request as it was received, but has the Result header
field set to 0x04 (Failure) and the Code field set to the appropriate
value. The AN-side agent MAY add a Status-Info TLV (Section 4.5) to
provide further information on the error, particularly if this is
recommended in Section 3.6.1.4 for the given Code value. If it does
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so, the various length fields and the # of TLVs field within the
message MUST be adjusted accordingly.
If the received message passes validation, the AN-side ANCP agent
"must" extract the information from the TLVs contained in the message
and present that information to the AN control application. In
addition, if the Result header field was set to 0x2 (AckAll) in the
original request, the AN-side agent "must" indicate to the AN control
application that a response is required. When the AN control
application indicates that it has processed the request successfully,
the AN-side agent MUST return a Port Management response message
which duplicates the request except that the Result header field is
set to 0x3 (Success). (The Code field, as in the original request,
has value 0.)
7.5. TLVs For DSL Line Configuration
Currently only the following TLV is specified for DSL line
configuration. More TLVs may be defined in a future version of this
specification or in ANCP extensions for individual service attributes
of a DSL line (e.g. rates, interleaving delay, multicast channel
entitlement access-list).
7.5.1. Service-Profile-Name TLV
Type: 0x0005
Description: Reference to a pre-configured profile on the DSLAM that
contains service specific data for the subscriber.
Length: up to 64 bytes
Value: ASCII string containing the profile name (which the NAS
learns from a policy server after a subscriber is authorized).
8. ANCP-Based DSL Remote Line Connectivity Testing
The use case and requirements for ANCP-Based DSL remote line
connectivity testing are specified in Section 3.3 of [RFC5851]
8.1. Control Context (Informative)
The NAS control application initiatea a request for remote
connectivity testing for a given access loop. The NAS control
application can provide loop count and timeout test parameters and
opaque data for its own use with the request. The loop count
parameter indicates the number of test messages or cells to be used.
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The timeout parameter indicates the longest that the NAS control
application will wait for a result.
The request is passed in a Port Management (OAM) message. If the NAS
control application has supplied test parameters, they are used,
otherwise the AN control application uses default test parameters.
If a loop count parameter provided by the NAS is outside the valid
range, the AN does not execute the test, but returns a result
indicating that the test has failed due to an invalid parameter. If
the test takes longer than the timeout value (default or provided by
the NAS) the AN control application can return a failure result
indicating timeout or else can send no response. The AN control
application can provide a human-readable string describing the test
results,for both failures and successes. If provided, this string is
included in the response. Responses always include the opaque data,
if any, provided by the NAS control application.
Figure 19 summarizes the interaction.
+-------------+ +-----+ +-------+ +----------------+
|Radius/AAA |----|NAS |-------| DSLAM |-----------| CPE |
|Policy Server| +-----+ +-------+ | (DSL Modem + |
+-------------+ |Routing Gateway)|
+----------------+
Port Management Message
(Remote Loopback ATM loopback
Trigger Request) OR EFM Loopback
1. ----------------> 2. --------->
<--------+
3. <---------------
Port Management Message
(Remote Loopback Test Response)
Figure 19: Message Flow For ANCP based OAM
8.2. Protocol Requirements
The DSL remote line connectivity testing capability is assigned
capability type 0x0004. No capability data is associated with this
capability.
8.2.1. Protocol Requirements On the NAS Side
The NAS-side ANCP agent MUST be able to create DSL-specific Port
Management (OAM) messages according to the format specified in
Section 8.3.
The NAS-side ANCP agent MUST conform to the normative requirements of
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Section 5.1.2.
The NAS-side ANCP agent "must" be able to accept any information
passed to it by the NAS control application that may validly be
included in any of the TLVs specified in Section 8.5.
The NAS-side ANCP agent MUST package that information as TLVs, and
MUST include these TLVs within the Port Management (OAM) message.
The NAS-side ANCP agent MUST follow the NAS-side procedures
associated with DSL-specific Port Management (OAM) messages as they
are specified in Section 8.4.
8.2.2. Protocol Requirements On the AN Side
The AN-side ANCP agent MUST conform to the normative requirements of
Section 5.1.2.
The AN-side ANCP agent MUST be able to receive and validate DSL-
specific Port Management (OAM) messages according to the format
specified in Section 8.3.
The AN-side ANCP agent MUST follow the AN-side procedures associated
with DSL-specific Port Management (OAM) messages as specified in
Section 8.4.
The NAS-side ANCP agent MUST be able to extract the information
contained in any of the TLVs listed in Section 8.2.1 and "must" make
that information available to the NAS control application.
8.3. Port Management (OAM) Message Format
The Port Management message for DSL line testing has the same format
as for DSL line configuration (see Section 7.3), with the following
differences:
o The Result field in the request SHOULD be set to AckAll (0x1), to
allow the NAS to receive the information contained in a successful
test response.
o The Function field MUST be set to 9 (Remote Loopback). (The
X-Function field continues to be 0.)
o The appended TLVs in the extension value field include testing-
related TLVs rather than subcriber service information.
The Port Management (OAM) message is illustrated in Figure 20.
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TCP/IP Encapsulating Header (Section 3.2) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ANCP General Message Header |
+ (Section 3.6.1) +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Port (unused) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Port Session Number (unused) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Event Sequence Number (unused) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R|x|x|x|x|x|x|x| Dur. (unused) | Function=9 | X-Function=0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Event Flags (unused) | Flow Control Flags (unused) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|x|x|x|x|x|x|x|x| Message Type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| # of TLVs | Extension Block length (bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Access line identifying TLV(s) ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Testing-related TLVs ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
NOTE: TLVs MAY be in a different order from what is shown in this
figure.
Figure 20: Port Management Message For DSL Line Remote Connectivity
Testing
8.4. Procedures
From the point of view of ANCP, it is permissible to attempt line
connectivity testing regardless of the state of the line. However,
testing could fail in some states due to technology limitations.
8.4.1. NAS-Side Procedures
When requested by the NAS control application and presented with the
necessary information to do so, the NAS-side agent MUST create and
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send a Port Management (OAM) request with the fixed fields set as
described in the previous section. The message MUST contain one or
more TLVs to identify an access line according the requirements of
Section 5.1.2. The NAS MAY include the Opaque-Data TLV and/or the
OAM-Loopback-Test-Parameters TLV (defined in Section 8.5) to
configure the loopback test for that line.
8.4.2. AN-Side Procedures
The AN-side ANCP agent SHOULD validate each message against the
specifications given in Section 8.3 and the TLV specifications given
in Section 5.1.2 and Section 8.5. If it finds an error it MUST
return a Port Management response message which copies the Port
Management request as it was received, but has the Result header
field set to 0x04 (Failure) and the Code field set to the appropriate
value. Code value 1289 as described below MAY apply, as well as the
other Code values documented in Section 3.6.1.4. Code value 1289
SHOULD be used if the OAM-Loopback-Test-Parameters TLV is present
with an invalid value of the Count field. The AN-side agent MAY add
a Status-Info TLV (Section 4.5) to provide further information on the
error, particularly if this is recommended in Section 3.6.1.4 for the
given Code value. If it does so, the various length fields and the #
of TLVs field within the message MUST be adjusted accordingly.
If the received message passes validation, the AN-side ANCP agent
"must" extract the information from the TLVs contained in the message
and present that information to the AN control application. It MUST
NOT generate an immediate response to the request, but MUST instead
wait for the AN control application to indicate that the response
should be sent.
When requested by the AN control application and presented with the
necessary information to do so, the AN-side agent MUST create and
send a Port Management (OAM) response to the original request. The
Result field MUST be set to Success (0x3) or Failure (0x4), and the
Code field SHOULD be set to one of the following values, as indicated
by the AN control application.
1280 (0x500): Specified access line does not exist. See the
documentation of Code 3/1280 in Section 3.6.1.4 for more
information. The Result header field MUST be set to Failure
(0x4).
1281 (0x501): Loopback test timed out. The Result header field MUST
be set to Failure (0x4).
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1283 (0x503): DSL line status showtime
1284 (0x504): DSL line status idle
1285 (0x505): DSL line status silent
1286 (0x506): DSL line status training
1287 (0x507): DSL line integrity error
1288 (0x508): DSLAM resource not available. The Result header field
MUST be set to Failure (0x04).
1289 (0x509): Invalid test parameter. The Result header field MUST
be set to Failure (0x4).
All other fields of the request including the TLVs MUST be copied
into the response unchanged, except that in a successful response the
OAM-Loopback-Test-Parameters TLV MUST NOT appear. If the AN control
application has provided the necessary information, the AN-side agent
MUST also include an instance of the OAM-Loopback-Test-Response-
String TLV in the response.
8.5. TLVs For the DSL Line Remote Connectivity Testing Capability
The following TLVs have been defined for use with the DSL line
testing capability.
8.5.1. OAM-Loopback-Test-Parameters TLV
Type: 0x0007
Description: Parameters intended to override the default values for
this loopback test.
Length: 2 bytes
Value: two unsigned 1 byte fields described below (listed in order
of most to least significant).
Byte 1: Count. Number of loopback cells/messages that should
be generated on the local loop as part of the loopback test.
The Count value SHOULD be greater than 0 and less than or equal
to 32.
Byte 2: Timeout. Upper bound on the time in seconds that the
NAS will wait for a response from the DSLAM. The value 0 MAY
be used, but has a special meaning.
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The OAM-Loopback-Test-Parameters TLV is illustrated in Figure 21
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Type = 0x0007 | Length = 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Count | Timeout | Padding (=0) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 21: The OAM-Loopback-Test-Parameters TLV
8.5.2. Opaque-Data TLV
Type: 0x0008
Description: An 8 byte opaque field used by the NAS control
application for its own purposes (e.g., response correlation.)
The procedures in Section 8.4.2 ensure that if it is present in
the request it is copied unchanged to the response.
Length: 8 bytes
Value: Two 32 bit unsigned integers.
8.5.3. OAM-Loopback-Test-Response-String TLV
Type: 0x0009
Description: Suitably formatted string containing useful details
about the test that the NAS will display for the operator, exactly
as received from the DSLAM (no manipulation or interpretation by
the NAS).
Length: up to 128 bytes
Value: UTF-8 encoded string of text.
9. IANA Considerations
RFC EDITOR'S NOTE: please replace "RFCXXXX" with the number of this
specification.
9.1. Summary
This section requests the following IANA actions:
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o addition of message types to the GSMPv3 Message Type Name Space
registry;
o addition of a result type to the GSMPv3 Result Type Name Space
registry;
o extension of limits and addition of failure codes to the GSMPv3
Failure Response Message Name Space registry;
o establishment of the following new ANCP registries:
ANCP Function Codes;
ANCP Technology Types;
ANCP Command Codes;
ANCP TLV Types;
ANCP Capabilities.
9.2. IANA Actions
IANA is requested to add a new message category to the GSMPv3 Message
Type Name Space registry: "Access Network Control Protocol (ANCP)
Messages". IANA is requested to add the following entries under that
category:
+------------------+----------------+--------+-----------+
| Message Name | Message Number | Status | Reference |
+------------------+----------------+--------+-----------+
| Generic Response | 91 | | RFCXXXX |
| Provisioning | 93 | | RFCXXXX |
+------------------+----------------+--------+-----------+
IANA is requested to implement the following modification to the
General Switch Management Protocol version 3 (GSMPv3) Result Type
Name Space registry:
+--------------+-----------------------+-----------+
| Result Value | Result Type Name | Reference |
+--------------+-----------------------+-----------+
| 0 | Ignore (was Reserved) | RFCXXXX |
+--------------+-----------------------+-----------+
IANA is requested to implement the following modifications to the
GSMPv3 Failure Response Message Name Space:
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o Add the following note to the registry:
This registry is shared with the Access Node Control Protocol
(ANCP) [RFCXXXX]. GSMPv3 [RFC3292] allows values up to a
maximum of 255. ANCP extends this maximum to 4095. Hence
values above 255 are applicable to ANCP only.
o Extend the table of registration procedures as indicated.
o Add entries to the failure response message name table as
indicated.
o Replace the ranges of unassigned codes at the end of the failure
response message name table as indicated.
+----------+------------------------+---------------+
| Range | Registration Procedure | Notes |
+----------+------------------------+---------------+
| 256-4095 | IETF Consensus | ANCP use only |
+----------+------------------------+---------------+
+-------+----------------------------------------------+-----------+
| Value | Failure Response Message Name | Reference |
+-------+----------------------------------------------+-----------+
| 81 | Request message type not implemented (0x51) | RFCXXXX |
| 83 | Malformed message (0x53) | RFCXXXX |
| 84 | Mandatory TLV missing (0x54) | RFCXXXX |
| 85 | Invalid value in TLV (0x55) | RFCXXXX |
| 1280 | Specified access line does not exist (0x500) | RFCXXXX |
| 1281 | Loopback test timed out (0x501) | RFCXXXX |
| 1282 | Reserved (0x502) | RFCXXXX |
| 1283 | DSL line status showtime (0x503) | RFCXXXX |
| 1284 | DSL line status idle (0x504) | RFCXXXX |
| 1285 | DSL line status silent (0x505) | RFCXXXX |
| 1286 | DSL line status training (0x506) | RFCXXXX |
| 1287 | DSL line integrity error (0x507) | RFCXXXX |
| 1288 | DSLAM resource not available (0x508) | RFCXXXX |
| 1289 | Invalid test parameter (0x509) | RFCXXXX |
+-------+----------------------------------------------+-----------+
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+-----------+-------------------------------+-----------+
| Value | Failure Response Message Name | Reference |
+-----------+-------------------------------+-----------+
| 8-9 | Unassigned | |
| 47-59 | Unassigned | |
| 86-127 | Unassigned | |
| 160-255 | Unassigned | |
| 256-1279 | Unassigned (ANCP use only) | |
| 1290-4095 | Unassigned (ANCP use only) | |
+-----------+-------------------------------+-----------+
IANA is requested to create a new ANCP Port Management Function Name
registry, with the following initial entries. Additions to this
registry will be by IETF Consensus. Values may range from 0 to 255.
NOTE: future extensions of ANCP may need to establish sub-
registries of permitted X-Function values for specific values of
Function.
+----------------+-----------------------------------+-----------+
| Function Value | Function Name | Reference |
+----------------+-----------------------------------+-----------+
| 0 | Reserved | RFCXXXX |
| 1-7 | Unassigned | |
| 8 | Configure Connection Service Data | RFCXXXX |
| 9 | Remote Loopback | RFCXXXX |
| 10-255 | Unassigned | |
+----------------+-----------------------------------+-----------+
IANA is requested to create a new ANCP Version registry, with
additions by IETF consensus. The initial entries are as follows:
+---------+-------------+--------------+-----------+
| Version | Sub-Version | Name | Reference |
+---------+-------------+--------------+-----------+
| 3 | 1 | Pre-standard | |
| 3 | 2 | ANCPv1 | RFCXXXX |
+---------+-------------+--------------+-----------+
IANA is requested to create a new ANCP Technology Type registry, with
additions by IETF Consensus. Values may range from 0 to 255. The
initial entries are as follows:
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+-----------------+----------------+-----------+
| Tech Type Value | Tech Type Name | Reference |
+-----------------+----------------+-----------+
| 0 | Any technology | RFCXXXX |
| 1 | PON | RFCXXXX |
| 2-4 | Unassigned | |
| 5 | DSL | RFCXXXX |
| 6-254 | Unassigned | |
| 255 | Reserved | RFCXXXX |
+-----------------+----------------+-----------+
IANA is requested to create a new ANCP Command Code registry, with
additions by IETF Consensus. The initial entry is as follows:
+--------------------+-----------------------------+-----------+
| Command Code Value | Command Code Directive Name | Reference |
+--------------------+-----------------------------+-----------+
| 0 | Reserved | RFCXXXX |
+--------------------+-----------------------------+-----------+
IANA is requested to create a new ANCP TLV Type registry, with
additions by IETF Consensus. Values may range from 0x0000 to 0xFFFF.
New assignments should be in the range of values from 0x0100 upwards.
The initial entries are as follows:
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+--------------+----------------------------------------+-----------+
| Type Code | TLV Name | Reference |
+--------------+----------------------------------------+-----------+
| 0x0000 | Reserved | RFCXXXX |
| 0x0001 | Access-Loop-Circuit-ID | RFCXXXX |
| 0x0002 | Access-Loop-Remote-Id | RFCXXXX |
| 0x0003 | Access-Aggregation-Circuit-ID-ASCII | RFCXXXX |
| 0x0004 | DSL-Line-Attributes | RFCXXXX |
| 0x0005 | Service-Profile-Name | RFCXXXX |
| 0x0006 | Access-Aggregation-Circuit-ID-Binary | RFCXXXX |
| 0x0007 | OAM-Loopback-Test-Parameters | RFCXXXX |
| 0x0008 | Opaque-Data | RFCXXXX |
| 0x0009 | OAM-Loopback-Test-Response-String | RFCXXXX |
| 0x000a-0x001 | Unassigned | |
| 0 | | |
| 0x0011 | Command | RFCXXXX |
| 0x0012-0x008 | Unassigned | |
| 0 | | |
| 0x0081 | Actual-Net-Data-Upstream | RFCXXXX |
| 0x0082 | Actual-Net-Data-Rate-Downstream | RFCXXXX |
| 0x0083 | Minimum-Net-Data-Rate-Upstream | RFCXXXX |
| 0x0084 | Minimum-Net-Data-Rate-Downstream | RFCXXXX |
| 0x0085 | Attainable-Net-Data-Rate-Upstream | RFCXXXX |
| 0x0086 | Attainable-Net-Data-Rate-Downstream | RFCXXXX |
| 0x0087 | Maximum-Net-Data-Rate-Upstream | RFCXXXX |
| 0x0088 | Maximum-Net-Data-Rate-Downstream | RFCXXXX |
| 0x0089 | Minimum-Net-Low-Power-Data-Rate-Upstre | RFCXXXX |
| | am | |
| 0x008A | Minimum-Net-Low-Power-Data-Rate-Downst | RFCXXXX |
| | ream | |
| 0x008B | Maximum-Interleaving-Delay-Upstream | RFCXXXX |
| 0x008C | Actual-Interleaving-Delay-Upstream | RFCXXXX |
| 0x008D | Maximum-Interleaving-Delay-Downstream | RFCXXXX |
| 0x008E | Actual-Interleaving-Delay-Downstream | RFCXXXX |
| 0x008F | DSL-Line-State | RFCXXXX |
| 0x0090 | Access-Loop-Encapsulation | RFCXXXX |
| 0x0091 | DSL-Type | RFCXXXX |
| 0x092-0x0105 | Unassigned | |
| 0x0106 | Status-Info | RFCXXXX |
| 0x0107-0x0FF | Unassigned | |
| F | | |
| 0x1000 | Target (single access line variant) | RFCXXXX |
| 0x1001 - | Reserved for Target variants | RFCXXXX |
| 0x1020 | | |
| 0x1021-0xFFF | Unassigned | |
| F | | |
+--------------+----------------------------------------+-----------+
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IANA is requested to create a new ANCP Capability registry, with
additions by IETF Consensus. Values may range from 0 to 255. The
specification for a given capability MUST indicate whether it applies
to a specific access technology or applies to all access
technologies. The specification MUST further indicate whether the
capability is associated with any capability data. The initial
entries in the ANCP capability registry are as follows:
+-------+-------------------+------------+--------------+-----------+
| Value | Capability Type | Technology | Capability | Reference |
| | Name | | Data | |
+-------+-------------------+------------+--------------+-----------+
| 0 | Reserved | | | RFCXXXX |
| 1 | DSL Topology | DSL | None | RFCXXXX |
| | Discovery | | | |
| 2 | DSL Line | DSL | None | RFCXXXX |
| | Configuration | | | |
| 3 | Reserved | | | RFCXXXX |
| 4 | DSL Line Testing | DSL | None | RFCXXXX |
| 5-255 | Unassigned | | | |
+-------+-------------------+------------+--------------+-----------+
10. Security Considerations
Security of the ANCP protocol is discussed in [RFC5713]. A number of
security requirements on ANCP are stated in Section 8 of that
document. Those applicable to ANCP itself are listed here:
o The protocol solution MUST offer authentication of the AN to the
NAS.
o The protocol solution MUST offer authentication of the NAS to the
AN.
o The protocol solution MUST allow authorization to take place at
the NAS and the AN.
o The protocol solution MUST offer replay protection.
o The protocol solution MUST provide data-origin authentication.
o The protocol solution MUST be robust against denial-of-service
(DoS) attacks. In this context, the protocol solution MUST
consider a specific mechanism for the DoS that the user might
create by sending many IGMP messages.
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o The protocol solution SHOULD offer confidentiality protection.
o The protocol solution SHOULD ensure that operations in default
configuration guarantees a low number of AN/NAS protocol
interactions.
Most of these requirements relate to secure transport of ANCP.
Robustness against denial-of-service attacks partly depends on
transport and partly on protocol design. Ensuring a low number of
AN/NAS protocol interactions in default mode is purely a matter of
protocol design.
For secure transport, either the combination of IPsec with IKEv2
(references below) or the use of TLS [RFC5246] will meet the
requirements listed above. The deciding point is a detail of
protocol design that was unavailable when [RFC5713] was written. The
ANCP adjacency is a major point of vulnerability for denial-of-
service attacks. If the adjacency can be shut down, either the AN
clears its state pending reestablishment of the adjacency, or the
possibility of mismatches between the AN's and NAS's view of state on
the AN is opened up. Two ways to cause an adjacency to be taken down
are to modify messages so that the ANCP agents conclude that they are
no longer synchronized, or to attack the underlying TCP session. TLS
will protect message contents, but not the TCP connection. One has
to use either IPsec or the TCP authentication option [RFC5925] for
that. Hence the conclusion that ANCP MUST run over IPsec with IKEv2
for authentication and key management.
In greater detail: the ANCP stack MUST include IPsec [RFC4301]
running in transport mode, since the AN and NAS are the endpoints of
the path. The Encapsulating Security Payload (ESP) [RFC4303] MUST be
used, in order to satisfy the requirement for data confidentiality.
ESP MUST be configured for the combination of confidentiality,
integrity, anti-replay capability. The traffic flow confidentiality
service of ESP is unnecessary and, in fact, unworkable in the case of
ANCP.
IKEv2 [RFC5996] is also REQUIRED, to meet the requirements for mutual
authentication and authorization. Since the NAS and AN MAY be in
different trust domains, the use of certificates for mutual
authentication could be the most practical approach. However, this
is up to the operator(s) concerned.
The AN MUST play the role of initiator of the IKEv2 conversation.
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11. Acknowledgements
The authors would like to thank everyone who provided comments or
inputs to this document. Swami Subramanian was an early member of
the authors' team. The ANCP Working Group is grateful to Roberta
Maglione, who served as design team member and primary editor of this
document for two years before stepping down. The authors acknowledge
the inputs provided by Wojciech Dec, Peter Arberg, Josef Froehler,
Derek Harkness, Kim Hyldgaard, Sandy Ng, Robert Peschi, and Michel
Platnic.
12. References
12.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3292] Doria, A., Hellstrand, F., Sundell, K., and T. Worster,
"General Switch Management Protocol (GSMP) V3", RFC 3292,
June 2002.
[RFC3293] Worster, T., Doria, A., and J. Buerkle, "General Switch
Management Protocol (GSMP) Packet Encapsulations for
Asynchronous Transfer Mode (ATM), Ethernet and
Transmission Control Protocol (TCP)", RFC 3293, June 2002.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, November 2003.
[RFC4301] Kent, S. and K. Seo, "Security Architecture for the
Internet Protocol", RFC 4301, December 2005.
[RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)",
RFC 4303, December 2005.
[RFC5996] Kaufman, C., Hoffman, P., Nir, Y., and P. Eronen,
"Internet Key Exchange Protocol Version 2 (IKEv2)",
RFC 5996, September 2010.
12.2. Informative References
[G.988.1] "ITU-T recommendation G.998.1, ATM-based multi-pair
bonding", 2005.
[G.988.2] "ITU-T recommendation G.998.2, Ethernet-based multi-pair
bonding,", 2005.
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[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008.
[RFC5713] Moustafa, H., Tschofenig, H., and S. De Cnodder, "Security
Threats and Security Requirements for the Access Node
Control Protocol (ANCP)", RFC 5713, January 2010.
[RFC5851] Ooghe, S., Voigt, N., Platnic, M., Haag, T., and S.
Wadhwa, "Framework and Requirements for an Access Node
Control Mechanism in Broadband Multi-Service Networks",
RFC 5851, May 2010.
[RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP
Authentication Option", RFC 5925, June 2010.
[TR-058] Elias, M. and S. Ooghe, "DSL Forum TR-058, Multi-Service
Architecture & Framework Requirements", September 2003.
[TR-059] Anschutz, T., "DSL Forum TR-059, DSL Evolution -
Architecture Requirements for the Support of QoS-Enabled
IP Services", September 2003.
[TR-092] DSL Forum (now the Broadband Forum), "DSL Forum TR-092,
Broadband Remote access server requirements document",
2005.
[TR-101] Cohen et al, "Architecture & Transport: "Migration to
Ethernet Based DSL Aggregation", DSL Forum TR-101", 2005.
[TR-147] Voight et al, "Layer 2 Control Mechanism For Broadband
Multi-Service Architectures", 2008.
[US_ASCII]
American National Standards Institute, "Coded Character
Set - 7-bit American Standard Code for Information
Interchange", ANSI X.34, 1986.
Authors' Addresses
Sanjay Wadhwa
Alcatel-Lucent
Phone:
Fax:
Email: sanjay.wadhwa@alcatel-lucent.com
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Jerome Moisand
Juniper Networks
10 Technology Park Drive
Westford, MA 01886
USA
Phone:
Fax:
Email: jmoisand@juniper.net
Thomas Haag
Deutsche Telekom
Heinrich-Hertz-Strasse 3-7
Darmstadt, 64295
Germany
Phone: +49 6151 628 2088
Fax:
Email: haagt@telekom.de
Norbert Voigt
Nokia Siemens Networks
Siemensallee 1
Greifswald 17489
Germany
Email: norbert.voigt@nsn.com
Tom Taylor (editor)
Huawei Technologies
Ottawa
Canada
Email: tom111.taylor@bell.net
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