Internet DRAFT - draft-ietf-radext-ip-port-radius-ext
draft-ietf-radext-ip-port-radius-ext
Network Working Group D. Cheng
Internet-Draft Huawei
Intended status: Standards Track J. Korhonen
Expires: September 18, 2016 Broadcom Corporation
M. Boucadair
Orange
S. Sivakumar
Cisco Systems
March 17, 2016
RADIUS Extensions for IP Port Configuration and Reporting
draft-ietf-radext-ip-port-radius-ext-09
Abstract
This document defines three new RADIUS attributes. For devices that
implementing IP port ranges, these attributes are used to communicate
with a RADIUS server in order to configure and report TCP/UDP ports
and ICMP identifiers, as well as mapping behavior for specific hosts.
This mechanism can be used in various deployment scenarios such as
Carrier-Grade NAT, IPv4/IPv6 translators, Provider WLAN Gateway, etc.
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 RFC 2119 [RFC2119].
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."
This Internet-Draft will expire on September 18, 2016.
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Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Extensions of RADIUS Attributes and TLVs . . . . . . . . . . 5
3.1. Extended Attributes for IP Ports . . . . . . . . . . . . 6
3.1.1. IP-Port-Limit-Info Attribute . . . . . . . . . . . . 6
3.1.2. IP-Port-Range Attribute . . . . . . . . . . . . . . . 8
3.1.3. IP-Port-Forwarding-Map Attribute . . . . . . . . . . 10
3.2. RADIUS TLVs for IP Ports . . . . . . . . . . . . . . . . 13
3.2.1. IP-Port-Type TLV . . . . . . . . . . . . . . . . . . 13
3.2.2. IP-Port-Limit TLV . . . . . . . . . . . . . . . . . . 14
3.2.3. IP-Port-Ext-IPv4-Addr TLV . . . . . . . . . . . . . . 15
3.2.4. IP-Port-Int-IPv4-Addr TLV . . . . . . . . . . . . . . 16
3.2.5. IP-Port-Int-IPv6-Addr TLV . . . . . . . . . . . . . . 17
3.2.6. IP-Port-Int-Port TLV . . . . . . . . . . . . . . . . 18
3.2.7. IP-Port-Ext-Port TLV . . . . . . . . . . . . . . . . 18
3.2.8. IP-Port-Alloc TLV . . . . . . . . . . . . . . . . . . 19
3.2.9. IP-Port-Range-Start TLV . . . . . . . . . . . . . . . 20
3.2.10. IP-Port-Range-End TLV . . . . . . . . . . . . . . . . 21
3.2.11. IP-Port-Local-Id TLV . . . . . . . . . . . . . . . . 22
4. Applications, Use Cases and Examples . . . . . . . . . . . . 23
4.1. Managing CGN Port Behavior using RADIUS . . . . . . . . . 23
4.1.1. Configure IP Port Limit for a User . . . . . . . . . 24
4.1.2. Report IP Port Allocation/Deallocation . . . . . . . 26
4.1.3. Configure Forwarding Port Mapping . . . . . . . . . . 27
4.1.4. An Example . . . . . . . . . . . . . . . . . . . . . 29
4.2. Report Assigned Port Set for a Visiting UE . . . . . . . 30
5. Table of Attributes . . . . . . . . . . . . . . . . . . . . . 31
6. Security Considerations . . . . . . . . . . . . . . . . . . . 32
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 32
7.1. IANA Considerations on New IPFIX Information Elements . . 32
7.2. IANA Considerations on New RADIUS Attributes . . . . . . 33
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7.3. IANA Considerations on New RADIUS TLVs . . . . . . . . . 33
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 33
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 34
9.1. Normative References . . . . . . . . . . . . . . . . . . 34
9.2. Informative References . . . . . . . . . . . . . . . . . 34
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 36
1. Introduction
In a broadband network, customer information is usually stored on a
RADIUS server [RFC2865]. At the time when a user initiates an IP
connection request, if this request is authorized, the RADIUS server
will populate the user's configuration information to the Network
Access Server (NAS), which is often referred to as a Broadband
Network Gateway (BNG) in broadband access networks. The Carrier-
Grade NAT (CGN) function may also be implemented on the BNG. Within
this document, the CGN may perform NAT44 [RFC3022], NAT64 [RFC6146],
or Dual-Stack Lite AFTR [RFC6333] function. In such case, the CGN
TCP/UDP port (or ICMP identifier) mapping(s) behavior(s) can be part
of the configuration information sent from the RADIUS server to the
NAS/BNG. The NAS/BNG may also report to the RADIUS Server the port/
identifier mapping behavior applied by the CGN to a user session to
the RADIUS server, as part of the accounting information sent from
the NAS/BNG to a RADIUS server.
When IP packets traverse the CGN, it performs TCP/UDP source port
mapping or ICMP identifier mapping as required. A TCP/ UDP source
port or ICMP identifier, along with source IP address, destination IP
address, destination port and protocol identifier if applicable,
uniquely identify a session. Since the number space of TCP/UDP ports
and ICMP identifiers in CGN's external realm is shared among multiple
users assigned with the same IPv4 address, the total number of a
user's simultaneous IP sessions is likely to be subject to port quota
(see Section 5 of [RFC6269]).
The attributes defined in this document may also be used to report
the assigned port range in some deployments such as Provider WLAN
[I-D.gundavelli-v6ops-community-wifi-svcs]. For example, a visiting
host can be managed by a CPE (Customer Premises Equipment ) which
will need to report the assigned port range to the service platform.
This is required for identification purposes (see TR-146 [TR-146] for
more details).
This document proposes three new attributes as RADIUS protocol's
extensions, and they are used for separate purposes as follows:
1. IP-Port-Limit-Info: This attribute may be carried in RADIUS
Access-Accept, Access-Request, Accounting-Request or CoA-Request
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packet. The purpose of this attribute is to limit the total
number of TCP/UDP ports and/or ICMP identifiers allocated to a
user, associated with one or more IPv4 addresses.
2. IP-Port-Range: This attribute may be carried in RADIUS
Accounting-Request packet. The purpose of this attribute is to
report by an address sharing device (e.g., a CGN) to the RADIUS
server the range of TCP/UDP ports and/or ICMP identifiers that
have been allocated or deallocated associated with a given IPv4
address for a user.
3. IP-Port-Forwarding-Map: This attribute may be carried in RADIUS
Access-Accept, Access-Request, Accounting-Request or CoA-Request
packet. The purpose of this attribute is to specify how an IPv4
address and a TCP/ UDP port (or an ICMP identifier) is mapped to
another IPv4 address and a TCP/UDP port (or an ICMP identifier).
IPFIX Information Elements [RFC7012] can be used for IP flow
identification and representation over RADIUS. This document
provides a mapping between RADIUS TLV and IPFIX Information Element
Identifiers. As a consequence, new IPFIX Information Elements are
defined by this document (see Section 3).
2. Terminology
This document makes use of the following terms:
o IP Port: refers to the port numbers of IP transport protocols,
including TCP port, UDP port and ICMP identifier.
o IP Port Type: refers to one of the following: (1) TCP/UDP port and
ICMP identifier, (2) TCP port and UDP port, (3) TCP port, (4) UDP
port, or (5) ICMP identifier.
o IP Port Limit: denotes the maximum number of IP ports for a
specific IP port type, that a device supporting port ranges can
use when performing port number mapping for a specific user.
Note, this limit is usually associated with one or more IPv4
addresses.
o IP Port Range: specifies a set of contiguous IP ports, indicated
by the lowest numerical number and the highest numerical number,
inclusively.
o Internal IP Address: refers to the IP address that is used as a
source IP address in an outbound IP packet sent towards a device
supporting port ranges in the internal realm.
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o External IP Address: refers to the IP address that is used as a
source IP address in an outbound IP packet after traversing a
device supporting port ranges in the external realm.
o Internal Port: is a UDP or TCP port, or an ICMP identifier, which
is allocated by a host or application behind a device supporting
port ranges for an outbound IP packet in the internal realm.
o External Port: is a UDP or TCP port, or an ICMP identifier, which
is allocated by a device supporting port ranges upon receiving an
outbound IP packet in the internal realm, and is used to replace
the internal port that is allocated by a user or application.
o External realm: refers to the networking segment where external IP
addresses are used in respective of the device supporting port
ranges.
o Internal realm: refers to the networking segment that is behind a
device supporting port ranges and where internal IP addresses are
used.
o Mapping: associates with a device supporting port ranges for a
relationship between an internal IP address, internal port and the
protocol, and an external IP address, external port, and the
protocol.
o Port-based device: a device that is capable of providing IP
address and IP port mapping services and in particular, with the
granularity of one or more subsets within the 16-bit IP port
number range. A typical example of this device is a CGN, CPE,
Provider WLAN Gateway, etc.
Note that the definitions of "internal IP address", "internal port",
"internal realm", "external IP address", "external port", "external
realm", and "mapping" are the same as defined in Port Control
Protocol (PCP) [RFC6887], and the Common Requirements for Carrier-
Grade NATs (CGNs) [RFC6888].
3. Extensions of RADIUS Attributes and TLVs
These three new attributes are defined in the following sub-sections:
1. IP-Port-Limit-Info Attribute
2. IP-Port-Range Attribute
3. IP-Port-Forwarding-Map Attribute
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All these attributes are allocated from the RADIUS "Extended Type"
code space per [RFC6929].
These attributes and their embedded TLVs (refer to Section 3.2) are
defined with globally unique names and follow the guideline in
Section 2.7.1 of [RFC6929].
In all the figures describing the RADIUS attributes and TLV formats
in the following sub-sections, the fields are transmitted from left
to right.
3.1. Extended Attributes for IP Ports
3.1.1. IP-Port-Limit-Info Attribute
This attribute is of type "TLV" as defined in the RADIUS Protocol
Extensions [RFC6929]. It contains the following sub-attributes:
o an IP-Port-Type TLV (see Section 3.2.1),
o an IP-Port-Limit TLV (see Section 3.2.2),
o an optional IP-Port-Ext-IPv4-Addr TLV (see Section 3.2.3).
It specifies the maximum number of IP ports as indicated in IP-Port-
Limit TLV, of a specific port type as indicated in IP-Port-Type TLV,
and associated with a given IPv4 address as indicated in IP-Port-Ext-
IPv4-Addr TLV for an end user.
Note that when IP-Port-Ext-IPv4-Addr TLV is not included as part of
the IP-Port-Limit-Info Attribute, the port limit applies to all the
IPv4 addresses managed by the port device, e.g., a CGN or NAT64
device.
The IP-Port-Limit-Info Attribute MAY appear in an Access-Accept
packet. It MAY also appear in an Access-Request packet as a
preferred maximum number of IP ports indicated by the device
supporting port ranges co-located with the NAS, e.g., a CGN or NAT64.
However, the RADIUS server is not required to honor such a
preference.
The IP-Port-Limit-Info Attribute MAY appear in a CoA-Request packet.
The IP-Port-Limit-Info Attribute MAY appear in an Accounting-Request
packet.
The IP-Port-Limit-Info Attribute MUST NOT appear in any other RADIUS
packet.
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The format of the IP-Port-Limit-Info Attribute is shown in Figure 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Extended-Type | Value ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1
Type
241 (To be confirmed by IANA).
Length
This field indicates the total length in bytes of all fields of
this attribute, including the Type, Length, Extended-Type, and the
entire length of the embedded TLVs.
Extended-Type
TBD1.
Value
This field contains a set of TLVs as follows:
IP-Port-Type TLV
This TLV contains a value that indicates the IP port type.
Refer to Section 3.2.1.
IP-Port-Limit TLV
This TLV contains the maximum number of IP ports of a specific
IP port type and associated with a given IPv4 address for an
end user. This TLV must be included in the IP-Port-Limit-Info
Attribute. Refer to Section 3.2.2.
IP-Port-Ext-IPv4-Addr TLV
This TLV contains the IPv4 address that is associated with the
IP port limit contained in the IP-Port-Limit TLV. This TLV is
optionally included as part of the IP-Port-Limit-Info
Attribute. Refer to Section 3.2.3.
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IP-Port-Limit-Info Attribute is associated with the following
identifier: 241.Extended-Type(TBD1).
3.1.2. IP-Port-Range Attribute
This attribute is of type "TLV" as defined in the RADIUS Protocol
Extensions [RFC6929]. It contains the following sub-attributes:
o an IP-Port-Type TLV (see Section 3.2.1),
o an IP-Port-Range-Start TLV (see Section 3.2.9),
o an IP-Port-Range-End TLV (see Section 3.2.10),
o an IP-Port-Alloc TLV (see Section 3.2.8),
o an optional IP-Port-Ext-IPv4-Addr TLV (see Section 3.2.3),
o an optional IP-Port-Local-Id TLV (see Section 3.2.11).
This attribute contains a range of contiguous IP ports of a specific
port type and associated with an IPv4 address that is either
allocated or deallocated by a device for a given user, and the
information is intended to be sent to RADIUS server.
This attribute can be used to convey a single IP port number; in such
case IP-Port-Range-Start and IP-Port-Range-End conveys the same
value.
Within an IP-Port-Range Attribute, the IP-Port-Alloc TLV is always
included. For port allocation, both IP-Port-Range-Start TLV and IP-
Port-Range-End TLV must be included; for port deallocation, the
inclusion of these two TLVs is optional and if not included, it
implies that all ports that are previously allocated are now
deallocated. Both IP-Port-Ext-IPv4-Addr TLV and IP-Port-Local-Id TLV
are optional and if included, they are used by a port device (e.g., a
CGN device) to identify the end user.
The IP-Port-Range Attribute MAY appear in an Accounting-Request
packet.
The IP-Port-Range Attribute MUST NOT appear in any other RADIUS
packet.
The format of the IP-Port-Range Attribute is shown in Figure 2.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Extended-Type | Value ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2
Type
241 (To be confirmed by IANA).
Length
This field indicates the total length in bytes of all fields of
this attribute, including the Type, Length, Extended-Type, and the
entire length of the embedded TLVs.
Extended-Type
TBD2.
Value
This field contains a set of TLVs as follows:
IP-Port-Type TLV
This TLV contains a value that indicates the IP port type.
Refer to Section 3.2.1.
IP-Port-Alloc TLV
This TLV contains a flag to indicate that the range of the
specified IP ports for either allocation or deallocation. This
TLV must be included as part of the IP-Port-Range Attribute.
Refer to Section 3.2.8.
IP-Port-Range-Start TLV
This TLV contains the smallest port number of a range of
contiguous IP ports. To report the port allocation, this TLV
must be included together with IP-Port-Range-End TLV as part of
the IP-Port-Range Attribute. Refer to Section 3.2.9.
IP-Port-Range-End TLV
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This TLV contains the largest port number of a range of
contiguous IP ports. To report the port allocation, this TLV
must be included together with IP-Port-Range-Start TLV as part
of the IP-Port-Range Attribute. Refer to Section 3.2.10.
IP-Port-Ext-IPv4-Addr TLV
This TLV contains the IPv4 address that is associated with the
IP port range, as collectively indicated in the IP-Port-Range-
Start TLV and the IP-Port-Range-End TLV. This TLV is
optionally included as part of the IP-Port-Range Attribute.
Refer to Section 3.2.3.
IP-Port-Local-Id TLV
This TLV contains a local session identifier at the customer
premise, such as MAC address, interface ID, VLAN ID, PPP
sessions ID, VRF ID, IPv6 address/prefix, etc. This TLV is
optionally included as part of the IP-Port-Range Attribute.
Refer to Section 3.2.11.
The IP-Port-Range attribute is associated with the following
identifier: 241.Extended-Type(TBD2).
3.1.3. IP-Port-Forwarding-Map Attribute
This attribute is of type "TLV" as defined in the RADIUS Protocol
Extensions [RFC6929]. It contains the following sub-attributes:
o an IP-Port-Type TLV (see Section 3.2.1),
o an IP-Port-Int-Port TLV (see Section 3.2.6),
o an IP-Port-Ext-Port TLV (see Section 3.2.7),
o either an IP-Port-Int-IPv4-Addr TLV (see Section 3.2.4) or an IP-
Port-Local-Id TLV (see Section 3.2.11),
o either an IP-Port-Int-IPv6-Addr TLV (see Section 3.2.5) or an IP-
Port-Local-Id TLV (see Section 3.2.11),
o an IP-Port-Ext-IPv4-Addr TLV (see Section 3.2.3).
The attribute contains a 2-byte IP internal port number that is
associated with an internal IPv4 or IPv6 address, or a locally
significant identifier at the customer site, and a 2-byte IP external
port number that is associated with an external IPv4 address. The
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internal IPv4 or IPv6 address, or the local identifier must be
included; the external IPv4 address may also be included.
The IP-Port-Forwarding-Map Attribute MAY appear in an Access-Accept
packet. It MAY also appear in an Access-Request packet to indicate a
preferred port mapping by the device co-located with NAS. However
the server is not required to honor such a preference.
The IP-Port-Forwarding-Map Attribute MAY appear in a CoA-Request
packet.
The IP-Port-Forwarding-Map Attribute MAY also appear in an
Accounting-Request packet.
The IP-Port-Forwarding-Map Attribute MUST NOT appear in any other
RADIUS packet.
The format of the IP-Port-Forwarding-Map Attribute is 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Extended-Type | Value ....
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3
Type
241 (To be confirmed by IANA).
Length
This field indicates the total length in bytes of all fields of
this attribute, including the Type, Length, Extended-Type, and the
entire length of the embedded TLVs.
Extended-Type
TBD3.
Value
This field contains a set of TLVs as follows:
IP-Port-Type TLV
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This TLV contains a value that indicates the IP port type.
Refer to Section 3.2.1.
IP-Port-Int-Port TLV
This TLV contains an internal IP port number associated with an
internal IPv4 or IPv6 address. This TLV must be included
together with IP-Port-Ext-Port TLV as part of the IP-Port-
Forwarding-Map attribute. Refer to Section 3.2.6.
IP-Port-Ext-Port TLV
This TLV contains an external IP port number associated with an
external IPv4 address. This TLV must be included together with
IP-Port-Int-Port TLV as part of the IP-Port-Forwarding-Map
attribute. Refer to Section 3.2.7.
IP-Port-Int-IPv4-Addr TLV
This TLV contains an IPv4 address that is associated with the
internal IP port number contained in the IP-Port-Int-Port TLV.
For IPv4 network, either this TLV or IP-Port-Local-Id TLV must
be included as part of the IP-Port-Forwarding-Map Attribute.
Refer to Section 3.2.4.
IP-Port-Int-IPv6-Addr TLV
This TLV contains an IPv4 address that is associated with the
internal IP port number contained in the IP-Port-Int-Port TLV.
For IPv6 network, either this TLV or IP-Port-Local-Id TLV must
be included as part of the IP-Port-Forwarding-Map Attribute.
Refer to Section 3.2.5.
IP-Port-Local-Id TLV
This TLV contains a local session identifier at the customer
premise, such as MAC address, interface ID, VLAN ID, PPP
sessions ID, VRF ID, IPv6 address/prefix, etc. Either this TLV
or IP-Port-Int-IP-Addr TLV must be included as part of the IP-
Port-Forwarding-Map Attribute. Refer to Section 3.2.11.
IP-Port-Ext-IPv4-Addr TLV
This TLV contains an IPv4 address that is associated with the
external IP port number contained in the IP-Port-Ext-Port TLV.
This TLV may be included as part of the IP-Port-Forwarding-Map
Attribute. Refer to Section 3.2.3.
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The IP-Port-Forwarding-Map Attribute is associated with the following
identifier: 241.Extended-Type(TBD3).
3.2. RADIUS TLVs for IP Ports
The TLVs that are included in the three attributes (see Section 3.1)
are defined in the following sub-sections. These TLVs use the format
defined in [RFC6929]. As the three attributes carry similar data, we
have defined a common set of TLVs which are used for all three
attributes. That is, the TLVs have the same name and number, when
encapsulated in any one of the three parent attributes. See
Section 3.1.1, Section 3.1.2, and Section 3.1.3 for a list of which
TLV is permitted within which parent attribute.
3.2.1. IP-Port-Type TLV
The format of IP-Port-Type TLV is shown in Figure 4. This attribute
carries IPFIX Information Element TBAx1, "transportType", which
indicates the type of IP transport as follows:
1:
Refer to TCP port, UDP port, and ICMP identifier as a whole.
2:
Refer to TCP port and UDP port as a whole.
3:
Refer to TCP port only.
4:
Refer to UDP port only.
5:
Refer to ICMP identifier only.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV-Type | Length | transportType
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
transportType |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4
TLV-Type
1
Length
6
transportType
Integer. This field contains the data (unsigned8) of
transportType (TBAx1) defined in IPFIX, right justified, and the
unused bits in this field MUST be set to zero.
IP-Port-Type TLV is included in the following Attributes:
o IP-Port-Limit-Info Attribute, identified as 241.TBD1.1 (see
Section 3.1.1).
o IP-Port-Range Attribute, identified as 241.TBD2.1 (see
Section 3.1.2).
o IP-Port-Forwarding-Mapping Attribute, identified as 241.TBD3.1
(see Section 3.1.3).
3.2.2. IP-Port-Limit TLV
The format of IP-Port-Limit TLV is shown in Figure 5. This attribute
carries IPFIX Information Element TBAx2, "natTransportLimit", which
indicates the maximum number of ports for a given IPv4 address
assigned to a user for a specified IP-Port-Type.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV-Type | Length | natTransportLimit
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
natTransportLimit |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5
TLV-Type
2
Length
6
natTransportLimit
Integer. This field contains the data (unsigned16) of
natTransportLimit (TBAx2) defined in IPFIX, right justified, and
the unused bits in this field MUST be set to zero.
IP-Port-Limit TLV is included as part of the IP-Port-Limit-Info
Attribute (refer to Section 3.1.1), identified as 241.TBD1.2.
3.2.3. IP-Port-Ext-IPv4-Addr TLV
The format of IP-Port-Ext-IPv4-Addr TLV is shown in Figure 6. This
attribute carries IPFIX Information Element 225,
"postNATSourceIPv4Address", which is the IPv4 source address after
NAT operation (refer to [IPFIX]).
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 | Length | postNATSourceIPv4Address
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
postNATSourceIPv4Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6
TLV-Type
3
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Length
6
postNATSourceIPv4Address
Integer. This field contains the data (ipv4Address) of
postNATSourceIPv4Address (225) defined in IPFIX.
IP-Port-Ext-IPv4-Addr TLV MAY be included in the following
Attributes:
o IP-Port-Limit-Info Attribute, identified as 241.TBD1.3 (see
Section 3.1.1).
o IP-Port-Range Attribute, identified as 241.TBD2.3 (see
Section 3.1.2).
o IP-Port-Forwarding-Mapping Attribute, identified as 241.TBD3.3
(see Section 3.1.3).
3.2.4. IP-Port-Int-IPv4-Addr TLV
The format of IP-Port-Int-IPv4 TLV is shown in Figure 7. This
attribute carries IPFIX Information Element 8, "sourceIPv4Address",
which is the IPv4 source address before NAT operation (refer to
[IPFIX]).
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 | Length | sourceIPv4Address
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
sourceIPv4Address |
+-+--+-+-+-+-+-+-++-+-+-+-+-+-+-+
Figure 7
TLV-Type
4
Length
6
sourceIPv4Address
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Integer. This field contains the data (ipv4Address) of
sourceIPv4Address (8) defined in IPFIX.
IP-Port-Int-IPv4-Addr TLV MAY be included as part of the IP-Port-
Forwarding-Map Attribute (refer to Section 3.1.3), identified as
241.TBD3.4.
3.2.5. IP-Port-Int-IPv6-Addr TLV
The format of IP-Port-Int-IPv6-Addr TLV is shown in Figure 8. This
attribute carries IPFIX Information Element 27, "sourceIPv6Address",
which is the IPv6 source address before NAT operation (refer to
[IPFIX]).
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 | Length | sourceIPv6Address
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
sourceIPv6Address
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
sourceIPv6Address
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
sourceIPv6Address
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
sourceIPv6Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8
TLV-Type
5
Length
18
sourceIPv6Address
IPv6 address (128 bits). This field contains the data
(ipv6Address) of sourceIPv6Address (27) defined in IPFIX.
IP-Port-Int-IPv6-Addr TLV MAY be included as part of the IP-Port-
Forwarding-Map Attribute (refer to Section 3.1.3), identified as
241.TBD3.5.
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3.2.6. IP-Port-Int-Port TLV
The format of IP-Port-Int-Port TLV is shown in Figure 9. This
attribute carries IPFIX Information Element 7, "sourceTransportPort",
which is the source transport number associated with an internal IPv4
or IPv6 address (refer to [IPFIX]).
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 | Length | sourceTransportPort
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
sourceTransportPort |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 9
TLV-Type
6
Length
6
sourceTransportPort
Integer. This field contains the data (unsigned16) of
sourceTrasnportPort (7) defined in IPFIX, right justified, and
unused bits MUST be set to zero.
IP-Port-Int-Port TLV is included as part of the IP-Port-Forwarding-
Map Attribute (refer to Section 3.1.3), identified as 241.TBD3.6.
3.2.7. IP-Port-Ext-Port TLV
The format of IP-Port-Ext-Port TLV is shown in Figure 10. This
attribute carries IPFIX Information Element 227,
"postNAPTSourceTransportPort", which is the transport number
associated with an external IPv4 address(refer to [IPFIX]).
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV-Type | Length | postNAPTSourceTransportPort
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
postNAPTSourceTransportPort |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 10
TLV-Type
7
Length
6
postNAPTSourceTransportPort
Integer. This field contains the data (unsigned16) of
postNAPTSourceTrasnportPort (227) defined in IPFIX, right
justified, and unused bits must be set to zero.
IP-Port-Ext-Port TLV is included as part of the IP-Port-Forwarding-
Map Attribute (refer to Section 3.1.3), identified as 241.TBD3.7.
3.2.8. IP-Port-Alloc TLV
The format of IP-Port-Alloc TLV is shown in Figure 11. This
attribute carries IPFIX Information Element 230, "natEvent", which is
a flag to indicate an action of NAT operation (refer to [IPFIX]).
When the value of natEvent is "1" (Create event), it means to
allocate a range of transport ports; when the value is "2", it means
to deallocate a range of transports ports. For the purpose of this
TLV, no other value is used.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV-Type | Length | natEvent
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
natEvent |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 11
TLV-Type
8
Length
6
natEvent
Integer. This field contains the data (unsigned8) of natEvent
(230) defined in IPFIX, right justified, and unused bits must be
set to zero. It indicates the allocation or deallocation of a
range of IP ports as follows:
1:
Allocation
2:
Deallocation
Reserved:
0.
IP-Port-Alloc TLV is included as part of the IP-Port-Range Attribute
(refer to Section 3.1.2), identified as 241.TBD2.8.
3.2.9. IP-Port-Range-Start TLV
The format of IP-Port-Range-Start TLV is shown in Figure 12. This
attribute carries IPFIX Information Element 361, "portRangeStart",
which is the smallest port number of a range of contiguous transport
ports (refer to [IPFIX]).
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV-Type | Length | portRangeStart
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
portRangeStart |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 12
TLV-Type
9
Length
6
portRangeStart
Integer. This field contains the data (unsigned16) of (361)
defined in IPFIX, right justified, and unused bits must be set to
zero.
IP-Port-Range-Start TLV is included as part of the IP-Port-Range
Attribute (refer to Section 3.1.2), identified as 241.TBD2.9.
3.2.10. IP-Port-Range-End TLV
The format of IP-Port-Range-End TLV is shown in Figure 13. This
attribute carries IPFIX Information Element 362, "portRangeEnd",
which is the largest port number of a range of contiguous transport
ports (refer to [IPFIX]).
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 | Length | portRangeEnd
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
portRangeEnd |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 13
TLV-Type
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10
Length
6
portRangeEnd
Integer. This field contains the data (unsigned16) of (362)
defined in IPFIX, right justified, and unused bits must be set to
zero.
IP-Port-Range-End TLV is included as part of the IP-Port-Range
Attribute (refer to Section 3.1.2), identified as 241.TBD2.10.
3.2.11. IP-Port-Local-Id TLV
The format of IP-Port-Local-Id TLV is shown in Figure 14. This
attribute carries IPFIX Information Element TBAx3, "localID", which
is a local significant identifier as explained below.
In some CGN deployment scenarios such as DS-Extra-Lite [RFC6619] and
Lightweight 4over6 [RFC7596], parameters at a customer premise such
as MAC address, interface ID, VLAN ID, PPP session ID, IPv6 prefix,
VRF ID, etc., may also be required to pass to the RADIUS server as
part of the accounting record.
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 | Length | localID ....
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 14
TLV-Type
11
Length
Variable number of bytes.
localID
string. This field contains the data (string) of (TBAx3) defined
in IPFIX. This is a local session identifier at the customer
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premise, such as MAC address, interface ID, VLAN ID, PPP sessions
ID, VRF ID, IPv6 address/prefix, etc.
IP-Port-Local-Id TLV MAY be included in the following Attributes:
o IP-Port-Range Attribute, identified as 241.TBD2.11 (see
Section 3.1.2).
o IP-Port-Forwarding-Mapping Attribute, identified as 241.TBD3.11
(see Section 3.1.3).
4. Applications, Use Cases and Examples
This section describes some applications and use cases to illustrate
the use of the attributes proposed in this document.
4.1. Managing CGN Port Behavior using RADIUS
In a broadband network, customer information is usually stored on a
RADIUS server, and the BNG acts as a NAS. The communication between
the NAS and the RADIUS server is triggered by a user when it signs in
to the Internet service, where either PPP or DHCP/DHCPv6 is used.
When a user signs in, the NAS sends a RADIUS Access-Request message
to the RADIUS server. The RADIUS server validates the request, and
if the validation succeeds, it in turn sends back a RADIUS Access-
Accept message. The Access-Accept message carries configuration
information specific to that user, back to the NAS, where some of the
information would pass on to the requesting user via PPP or DHCP/
DHCPv6.
A CGN function in a broadband network would most likely co-located on
a BNG. In that case, parameters for CGN port/identifier mapping
behavior for users can be configured on the RADIUS server. When a
user signs in to the Internet service, the associated parameters can
be conveyed to the NAS, and proper configuration is accomplished on
the CGN device for that user.
Also, CGN operation status such as CGN port/identifier allocation and
deallocation for a specific user on the BNG can also be transmitted
back to the RADIUS server for accounting purpose using the RADIUS
protocol.
RADIUS protocol has already been widely deployed in broadband
networks to manage BNG, thus the functionality described in this
specification introduces little overhead to the existing network
operation.
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In the following sub-sections, we describe how to manage CGN behavior
using RADIUS protocol, with required RADIUS extensions proposed in
Section 3.
4.1.1. Configure IP Port Limit for a User
In the face of IPv4 address shortage, there are currently proposals
to multiplex multiple users' connections over a smaller number of
shared IPv4 addresses, such as Carrier Grade NAT [RFC6888], Dual-
Stack Lite [RFC6333], NAT64 [RFC6146], etc. As a result, a single
IPv4 public address may be shared by hundreds or even thousands of
users. As indicated in [RFC6269], it is therefore necessary to
impose limits on the total number of ports available to an individual
user to ensure that the shared resource, i.e., the IPv4 address,
remains available in some capacity to all the users using it. The
support of IP port limit is also documented in [RFC6888] as a
requirement for CGN.
The IP port limit imposed to a specific user may be on the total
number of TCP and UDP ports plus the number of ICMP identifiers, or
with other granularities as defined in Section 3.1.1.
The per-user based IP port limit is configured on a RADIUS server,
along with other user information such as credentials. The value of
this IP port limit is based on service agreement and its
specification is out of the scope of this document.
When a user signs in to the Internet service successfully, the IP
port limit for the subscriber is passed by the RADIUS server to the
BNG, acting as a NAS and co-located with the CGN, using a new RADIUS
attribute called IP-Port-Limit-Info (defined in Section 3.1.1), along
with other configuration parameters. While some parameters are
passed to the user, the IP port limit is recorded on the CGN device
for imposing the usage of TCP/UDP ports and ICMP identifiers for that
user.
Figure 15 illustrates how RADIUS protocol is used to configure the
maximum number of TCP/UDP ports for a given user on a NAT44 device.
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User NAT44/NAS AAA
| BNG Server
| | |
| | |
|----Service Request------>| |
| | |
| |-----Access-Request -------->|
| | |
| |<----Access-Accept-----------|
| | (IP-Port-Limit-Info) |
| | (for TCP/UDP ports) |
|<---Service Granted ------| |
| (other parameters) | |
| | |
| (NAT44 external port |
| allocation and |
| IPv4 address assignment) |
| | |
Figure 15: RADIUS Message Flow for Configuring NAT44 Port Limit
The IP port limit created on a CGN device for a specific user using
RADIUS extension may be changed using RADIUS CoA message [RFC5176]
that carries the same RADIUS attribute. The CoA message may be sent
from the RADIUS server directly to the NAS, which once accepts and
sends back a RADIUS CoA ACK message, the new IP port limit replaces
the previous one.
Figure 16 illustrates how RADIUS protocol is used to increase the
TCP/UDP port limit from 1024 to 2048 on a NAT44 device for a specific
user.
User NAT44/NAS AAA
| BNG Server
| | |
| TCP/UDP Port Limit (1024) |
| | |
| |<---------CoA Request----------|
| | (IP-Port-Limit-Info) |
| | (for TCP/UDP ports) |
| | |
| TCP/UDP Port Limit (2048) |
| | |
| |---------CoA Response--------->|
| | |
Figure 16: RADIUS Message Flow for changing a user's NAT44 port limit
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4.1.2. Report IP Port Allocation/Deallocation
Upon obtaining the IP port limit for a user, the CGN device needs to
allocate a TCP/UDP port or an ICMP identifiers for the user when
receiving a new IP flow sent from that user.
As one practice, a CGN may allocate a bulk of TCP/UDP ports or ICMP
identifiers once at a time for a specific user, instead of one port/
identifier at a time, and within each port bulk, the ports/
identifiers may be randomly distributed or in consecutive fashion.
When a CGN device allocates bulk of TCP/UDP ports and ICMP
identifiers, the information can be easily conveyed to the RADIUS
server by a new RADIUS attribute called the IP-Port-Range (defined in
Section 3.1.2). The CGN device may allocate one or more TCP/UDP port
ranges or ICMP identifier ranges, or generally called IP port ranges,
where each range contains a set of numbers representing TCP/UDP ports
or ICMP identifiers, and the total number of ports/identifiers must
be less or equal to the associated IP port limit imposed for that
user. A CGN device may choose to allocate a small port range, and
allocate more at a later time as needed; such practice is good
because its randomization in nature.
At the same time, the CGN device also needs to decide the shared IPv4
address for that user. The shared IPv4 address and the pre-allocated
IP port range are both passed to the RADIUS server.
When a user initiates an IP flow, the CGN device randomly selects a
TCP/UDP port or ICMP identifier from the associated and pre-allocated
IP port range for that user to replace the original source TCP/UDP
port or ICMP identifier, along with the replacement of the source IP
address by the shared IPv4 address.
A CGN device may decide to "free" a previously assigned set of TCP/
UDP ports or ICMP identifiers that have been allocated for a specific
user but not currently in use, and with that, the CGN device must
send the information of the deallocated IP port range along with the
shared IPv4 address to the RADIUS server.
Figure 17 illustrates how RADIUS protocol is used to report a set of
ports allocated and deallocated, respectively, by a NAT44 device for
a specific user to the RADIUS server.
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Host NAT44/NAS AAA
| BNG Server
| | |
| | |
|----Service Request------>| |
| | |
| |-----Access-Request -------->|
| | |
| |<----Access-Accept-----------|
|<---Service Granted ------| |
| (other parameters) | |
... ... ...
| | |
| | |
| (NAT44 decides to allocate |
| a TCP/UDP port range for the user) |
| | |
| |-----Accounting-Request----->|
| | (IP-Port-Range |
| | for allocation) |
... ... ...
| | |
| (NAT44 decides to deallocate |
| a TCP/UDP port range for the user) |
| | |
| |-----Accounting-Request----->|
| | (IP-Port-Range |
| | for deallocation) |
| | |
Figure 17: RADIUS Message Flow for reporting NAT44 allocation/
deallocation of a port set
4.1.3. Configure Forwarding Port Mapping
In most scenarios, the port mapping on a NAT device is dynamically
created when the IP packets of an IP connection initiated by a user
arrives. For some applications, the port mapping needs to be pre-
defined allowing IP packets of applications from outside a CGN device
to pass through and "port forwarded" to the correct user located
behind the CGN device.
Port Control Protocol [RFC6887], provides a mechanism to create a
mapping from an external IP address and port to an internal IP
address and port on a CGN device just to achieve the "port
forwarding" purpose. PCP is a server-client protocol capable of
creating or deleting a mapping along with a rich set of features on a
CGN device in dynamic fashion. In some deployment, all users need is
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a few, typically just one pre-configured port mapping for
applications such as web cam at home, and the lifetime of such a port
mapping remains valid throughout the duration of the customer's
Internet service connection time. In such an environment, it is
possible to statically configure a port mapping on the RADIUS server
for a user and let the RADIUS protocol to propagate the information
to the associated CGN device.
Figure 18 illustrates how RADIUS protocol is used to configure a
forwarding port mapping on a NAT44 device by using RADIUS protocol.
Host NAT/NAS AAA
| BNG Server
| | |
|----Service Request------>| |
| | |
| |---------Access-Request------->|
| | |
| |<--------Access-Accept---------|
| | (IP-Port-Forwarding-Map) |
|<---Service Granted ------| |
| (other parameters) | |
| | |
| (Create a port mapping |
| for the user, and |
| associate it with the |
| internal IP address |
| and external IP address) |
| | |
| | |
| |------Accounting-Request------>|
| | (IP-Port-Forwarding-Map) |
Figure 18: RADIUS Message Flow for configuring a forwarding port
mapping
A port forwarding mapping that is created on a CGN device using
RADIUS extension as described above may also be changed using RADIUS
CoA message [RFC5176] that carries the same RADIUS associate. The
CoA message may be sent from the RADIUS server directly to the NAS,
which once accepts and sends back a RADIUS CoA ACK message, the new
port forwarding mapping then replaces the previous one.
Figure 19 illustrates how RADIUS protocol is used to change an
existing port mapping from (a:X) to (a:Y), where "a" is an internal
port, and "X" and "Y" are external ports, respectively, for a
specific user with a specific IP address
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Host NAT/NAS AAA
| BNG Server
| | |
| Internal IP Address |
| Port Map (a:X) |
| | |
| |<---------CoA Request----------|
| | (IP-Port-Forwarding-Map) |
| | |
| Internal IP Address |
| Port Map (a:Y) |
| | |
| |---------CoA Response--------->|
| | (IP-Port-Forwarding-Map) |
Figure 19: RADIUS Message Flow for changing a user's forwarding port
mapping
4.1.4. An Example
An Internet Service Provider (ISP) assigns TCP/UDP 500 ports for the
user Joe. This number is the limit that can be used for TCP/UDP ports
on a NAT44 device for Joe, and is configured on a RADIUS server.
Also, Joe asks for a pre-defined port forwarding mapping on the NAT44
device for his web cam applications (external port 5000 maps to
internal port 80).
When Joe successfully connects to the Internet service, the RADIUS
server conveys the TCP/UDP port limit (1000) and the forwarding port
mapping (external port 5000 to internal port 80) to the NAT44 device,
using IP-Port-Limit-Info Attribute and IP-Port-Forwarding-Map
attribute, respectively, carried by an Access-Accept message to the
BNG where NAS and CGN co-located.
Upon receiving the first outbound IP packet sent from Joe's laptop,
the NAT44 device decides to allocate a small port pool that contains
40 consecutive ports, from 3500 to 3540, inclusively, and also assign
a shared IPv4 address 192.0.2.15, for Joe. The NAT44 device also
randomly selects one port from the allocated range (say 3519) and use
that port to replace the original source port in outbound IP packets.
For accounting purpose, the NAT44 device passes this port range
(3500-3540) and the shared IPv4 address 192.0.2.15 together to the
RADIUS server using IP-Port-Range attribute carried by an Accounting-
Request message.
When Joe works on more applications with more outbound IP sessions
and the port pool (3500-3540) is close to exhaust, the NAT44 device
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allocates a second port pool (8500-8800) in a similar fashion, and
also passes the new port range (8500-8800) and IPv4 address
192.0.2.15 together to the RADIUS server using IP-Port-Range
attribute carried by an Accounting-Request message. Note when the
CGN allocates more ports, it needs to assure that the total number of
ports allocated for Joe is within the limit.
Joe decides to upgrade his service agreement with more TCP/UDP ports
allowed (up to 1000 ports). The ISP updates the information in Joe's
profile on the RADIUS server, which then sends a CoA-Request message
that carries the IP-Port-Limit-Info Attribute with 1000 ports to the
NAT44 device; the NAT44 device in turn sends back a CoA-ACK message.
With that, Joe enjoys more available TCP/UDP ports for his
applications.
When Joe travels, most of the IP sessions are closed with their
associated TCP/UDP ports released on the NAT44 device, which then
sends the relevant information back to the RADIUS server using IP-
Port-Range attribute carried by Accounting-Request message.
Throughout Joe's connection with his ISP Internet service,
applications can communicate with his web cam at home from external
realm directly traversing the pre-configured mapping on the CGN
device.
When Joe disconnects from his Internet service, the CGN device will
deallocate all TCP/UDP ports as well as the port-forwarding mapping,
and send the relevant information to the RADIUS server.
4.2. Report Assigned Port Set for a Visiting UE
Figure 20 illustrates an example of the flow exchange which occurs
when a visiting UE connects to a CPE offering WLAN service.
For identification purposes (see [RFC6967]), once the CPE assigns a
port set, it issues a RADIUS message to report the assigned port set.
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UE CPE NAS AAA
| BNG Server
| | |
| | |
|----Service Request------>| |
| | |
| |-----Access-Request -------->|
| | |
| |<----Access-Accept-----------|
|<---Service Granted ------| |
| (other parameters) | |
... | ... ...
|<---IP@----| | |
| | | |
| (CPE assigns a TCP/UDP port |
| range for this visiting UE) |
| | |
| |--Accounting-Request-...------------------->|
| | (IP-Port-Range |
| | for allocation) |
... | ... ...
| | | |
| | | |
| (CPE withdraws a TCP/UDP port |
| range for a visiting UE) |
| | |
| |--Accounting-Request-...------------------->|
| | (IP-Port-Range |
| | for deallocation) |
| | |
Figure 20: RADIUS Message Flow for reporting CPE allocation/
deallocation of a port set to a visiting UE
5. Table of Attributes
This document proposes three new RADIUS attributes and their formats
are as follows:
o IP-Port-Limit-Info: 241.TBD1.
o IP-Port-Range: 241.TBD2.
o IP-Port-Forwarding-Map: 241.TBD3.
Note to IANA: it is assumed that Extended-Type-1 "241" will be used
for these attributes.
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The following table provides a guide as what type of RADIUS packets
that may contain these attributes, and in what quantity.
Request Accept Reject Challenge Acct. # Attribute
Request
0+ 0+ 0 0 0+ TBA IP-Port-Limit-Info
0 0 0 0 0+ TBA IP-Port-Range
0+ 0+ 0 0 0+ TBA IP-Port-Forwarding-Map
The following table defines the meaning of the above table entries.
0 This attribute MUST NOT be present in packet.
0+ Zero or more instances of this attribute MAY be present in packet.
6. Security Considerations
This document does not introduce any security issue other than the
ones already identified in RADIUS [RFC2865].
7. IANA Considerations
This document requires new code point assignments for both IPFIX
Information Elements and RADIUS attributes as explained in the
following sub-sections.
It is assumed that Extended-Type-1 "241" will be used for RADIUS
attributes in Section 7.2.
7.1. IANA Considerations on New IPFIX Information Elements
The following are code point assignments for new IPFIX Information
Elements as requested by this document:
o transportType (refer to Section 3.2.1): The identifier of this
IPFIX Information Element is TBAx1. The data type of this IPFIX
Information Element is unsigned8, and the Element's value
indicates TCP/UDP ports and ICMP Identifiers (1), TCP/UDP ports
(2), TCP ports (3), UDP ports (4) or ICMP identifiers (5).
o natTransportLimit (refer to Section 3.2.2): The identifier of this
IPFIX Information Element is TBAx2. The data type of this IPFIX
Information Element is unsigned16, and the Element's value is the
max number of IP transport ports to be assigned to an end user
associated with one or more IPv4 addresses.
o localID (refer to Section 3.2.11): The identifier of this IPFIX
Information Element is TBAx3. The data type of this IPFIX
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Information Element is string, and the Element's value is an IPv4
or IPv6 address, a MAC address, a VLAN ID, etc.
7.2. IANA Considerations on New RADIUS Attributes
The authors request that Attribute Types and Attribute Values defined
in this document be registered by the Internet Assigned Numbers
Authority (IANA) from the RADIUS namespaces as described in the "IANA
Considerations" section of [RFC3575], in accordance with BCP 26
[RFC5226]. For RADIUS packets, attributes and registries created by
this document IANA is requested to place them at
http://www.iana.org/assignments/radius-types.
In particular, this document defines three new RADIUS attributes,
entitled "IP-Port-Limit-Info" (see Section 3.1.1), "IP-Port-Range"
(see Section 3.1.2) and "IP-Port-Forwarding-Map" (see Section 3.1.3),
with assigned values of 241.TBD1, 241.TBD2 and 241.TBD3 from the
Short Extended Space of [RFC6929]:
Type Name Meaning
---- ---- -------
241.TBD1 IP-Port-Limit-Info see Section 3.1.1
241.TBD2 IP-Port-Range see Section 3.1.2
241.TBD3 IP-Port-Forwarding-Map see Section 3.1.3
7.3. IANA Considerations on New RADIUS TLVs
This specification requests allocation of the following TLVs:
Name Value Meaning
---- ----- -------
IP-Port-Type 1 see Section 3.2.1
IP-Port-Limit 2 see Section 3.2.2
IP-Port-Ext-IPv4-Addr 3 see Section 3.2.3
IP-Port-Int-IPv4-Addr 4 see Section 3.2.4
IP-Port-Int-IPv6-Addr 5 see Section 3.2.5
IP-Port-Int-Port 6 see Section 3.2.6
IP-Port-Ext-Port 7 see Section 3.2.7
IP-Port-Alloc 8 see Section 3.2.8
IP-Port-Range-Start 9 see Section 3.2.9
IP-Port-Range-End 10 see Section 3.2.10
IP-Port-Local-Id 11 see Section 3.2.11
8. Acknowledgements
Many thanks to Dan Wing, Roberta Maglione, Daniel Derksen, David
Thaler, Alan Dekok, Lionel Morand, and Peter Deacon for their useful
comments and suggestions.
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Special thanks to Lionel Morand for the Shepherd review.
9. References
9.1. Normative References
[IPFIX] IANA, "IP Flow Information Export (IPFIX) Entities",
<http://www.iana.org/assignments/ipfix/ipfix.xhtml>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson,
"Remote Authentication Dial In User Service (RADIUS)",
RFC 2865, DOI 10.17487/RFC2865, June 2000,
<http://www.rfc-editor.org/info/rfc2865>.
[RFC3575] Aboba, B., "IANA Considerations for RADIUS (Remote
Authentication Dial In User Service)", RFC 3575,
DOI 10.17487/RFC3575, July 2003,
<http://www.rfc-editor.org/info/rfc3575>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
DOI 10.17487/RFC5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>.
[RFC6929] DeKok, A. and A. Lior, "Remote Authentication Dial In User
Service (RADIUS) Protocol Extensions", RFC 6929,
DOI 10.17487/RFC6929, April 2013,
<http://www.rfc-editor.org/info/rfc6929>.
[RFC7012] Claise, B., Ed. and B. Trammell, Ed., "Information Model
for IP Flow Information Export (IPFIX)", RFC 7012,
DOI 10.17487/RFC7012, September 2013,
<http://www.rfc-editor.org/info/rfc7012>.
9.2. Informative References
[I-D.gundavelli-v6ops-community-wifi-svcs]
Gundavelli, S., Grayson, M., Seite, P., and Y. Lee,
"Service Provider Wi-Fi Services Over Residential
Architectures", draft-gundavelli-v6ops-community-wifi-
svcs-06 (work in progress), April 2013.
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[RFC3022] Srisuresh, P. and K. Egevang, "Traditional IP Network
Address Translator (Traditional NAT)", RFC 3022,
DOI 10.17487/RFC3022, January 2001,
<http://www.rfc-editor.org/info/rfc3022>.
[RFC5176] Chiba, M., Dommety, G., Eklund, M., Mitton, D., and B.
Aboba, "Dynamic Authorization Extensions to Remote
Authentication Dial In User Service (RADIUS)", RFC 5176,
DOI 10.17487/RFC5176, January 2008,
<http://www.rfc-editor.org/info/rfc5176>.
[RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful
NAT64: Network Address and Protocol Translation from IPv6
Clients to IPv4 Servers", RFC 6146, DOI 10.17487/RFC6146,
April 2011, <http://www.rfc-editor.org/info/rfc6146>.
[RFC6269] Ford, M., Ed., Boucadair, M., Durand, A., Levis, P., and
P. Roberts, "Issues with IP Address Sharing", RFC 6269,
DOI 10.17487/RFC6269, June 2011,
<http://www.rfc-editor.org/info/rfc6269>.
[RFC6333] Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual-
Stack Lite Broadband Deployments Following IPv4
Exhaustion", RFC 6333, DOI 10.17487/RFC6333, August 2011,
<http://www.rfc-editor.org/info/rfc6333>.
[RFC6619] Arkko, J., Eggert, L., and M. Townsley, "Scalable
Operation of Address Translators with Per-Interface
Bindings", RFC 6619, DOI 10.17487/RFC6619, June 2012,
<http://www.rfc-editor.org/info/rfc6619>.
[RFC6887] Wing, D., Ed., Cheshire, S., Boucadair, M., Penno, R., and
P. Selkirk, "Port Control Protocol (PCP)", RFC 6887,
DOI 10.17487/RFC6887, April 2013,
<http://www.rfc-editor.org/info/rfc6887>.
[RFC6888] Perreault, S., Ed., Yamagata, I., Miyakawa, S., Nakagawa,
A., and H. Ashida, "Common Requirements for Carrier-Grade
NATs (CGNs)", BCP 127, RFC 6888, DOI 10.17487/RFC6888,
April 2013, <http://www.rfc-editor.org/info/rfc6888>.
[RFC6967] Boucadair, M., Touch, J., Levis, P., and R. Penno,
"Analysis of Potential Solutions for Revealing a Host
Identifier (HOST_ID) in Shared Address Deployments",
RFC 6967, DOI 10.17487/RFC6967, June 2013,
<http://www.rfc-editor.org/info/rfc6967>.
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[RFC7596] Cui, Y., Sun, Q., Boucadair, M., Tsou, T., Lee, Y., and I.
Farrer, "Lightweight 4over6: An Extension to the Dual-
Stack Lite Architecture", RFC 7596, DOI 10.17487/RFC7596,
July 2015, <http://www.rfc-editor.org/info/rfc7596>.
[TR-146] Broadband Forum, "TR-146: Subscriber Sessions",
<http://www.broadband-forum.org/technical/download/
TR-146.pdf>.
Authors' Addresses
Dean Cheng
Huawei
2330 Central Expressway
Santa Clara, California 95050
USA
Email: dean.cheng@huawei.com
Jouni Korhonen
Broadcom Corporation
3151 Zanker Road
San Jose 95134
USA
Email: jouni.nospam@gmail.com
Mohamed Boucadair
Orange
Rennes
France
Email: mohamed.boucadair@orange.com
Senthil Sivakumar
Cisco Systems
7100-8 Kit Creek Road
Research Triangle Park, North Carolina
USA
Email: ssenthil@cisco.com
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