Internet DRAFT - draft-bhandari-dhc-class-based-prefix
draft-bhandari-dhc-class-based-prefix
Internet Engineering Task Force S. Bhandari
Internet-Draft G. Halwasia
Intended status: Standards Track S. Gundavelli
Expires: January 16, 2014 Cisco Systems
H. Deng
China Mobile
L. Thiebaut
Alcatel-Lucent
J. Korhonen
Renesas Mobile
I. Farrer
Deutsche Telekom AG
July 15, 2013
DHCPv6 class based prefix
draft-bhandari-dhc-class-based-prefix-05
Abstract
This document introduces options to communicate property and
associate meta data with prefixes. It extends DHCPv6 prefix
delegation and address allocation using the meta data for selection
of prefixes and addresses.
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 January 16, 2014.
Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
Bhandari, et al. Expires January 16, 2014 [Page 1]
Internet-Draft DHCPv6 class based prefix July 2013
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
1.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 3
1.1.1. Mobile networks . . . . . . . . . . . . . . . . . . . 4
1.1.2. Home networks . . . . . . . . . . . . . . . . . . . . 4
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
1.3. Requirements Language . . . . . . . . . . . . . . . . . . 5
2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Prefix Property and Class Options . . . . . . . . . . . . 5
2.2. Consideration for different DHCPv6 entities . . . . . . . 6
2.2.1. Requesting Router Behavior for IA_PD allocation . . . 7
2.2.2. Delegating Router Behavior for IA_PD allocation . . . 8
2.2.3. DHCPv6 Client Behavior for IA_NA allocation . . . . . 9
2.2.4. DHCPv6 Server Behavior for IA_NA allocation . . . . . 9
2.3. Usage . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.3.1. Class based prefix and IA_NA allocation . . . . . . . 10
2.3.2. Class based prefix and IA_PD allocation . . . . . . . 10
2.3.3. Class based prefix and SLAAC . . . . . . . . . . . . 10
2.3.4. Class based prefix and applications . . . . . . . . . 11
3. Example Application . . . . . . . . . . . . . . . . . . . . . 11
3.1. Mobile gateway example . . . . . . . . . . . . . . . . . 11
3.1.1. Class based prefix delegation . . . . . . . . . . . . 13
3.1.2. IPv6 address assignment from class based prefix . . . 13
3.2. Homenet Example . . . . . . . . . . . . . . . . . . . . . 14
3.2.1. Class based prefix delegation to the HGW . . . . . . 15
3.2.2. IPv6 Assignment to Homenet hosts using stateful
DHCPv6 . . . . . . . . . . . . . . . . . . . . . . . 16
4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 17
5. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 17
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
6.1. OPTION_PREFIX_PROPERTY values . . . . . . . . . . . . . . 17
7. Security Considerations . . . . . . . . . . . . . . . . . . . 18
8. Change History (to be removed prior to publication as an RFC) 18
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 19
9.1. Normative References . . . . . . . . . . . . . . . . . . 19
9.2. Informative References . . . . . . . . . . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20
Bhandari, et al. Expires January 16, 2014 [Page 2]
Internet-Draft DHCPv6 class based prefix July 2013
1. Introduction
In IPv6 a network interface can acquire multiple addresses from the
same scope. In such a multi-prefix network each of the multiple
prefixes can have a specific property and purpose associated with it.
Example: In a mobile network a mobile device can be assigned a prefix
from its home network and another from the visiting network that it
is attached to. Another example is a prefix may provide free
Internet access without offering any quality of service guarantees
while another prefix may be charged along with providing quality of
service guarantees for network service access. A prefix can have
well defined properties that is universal and have a meta data
associated with it that communicates its local significance. The
properties and meta data of prefix will be relevant for prefix
delegation, source address selection as elaborated in the subsequent
sections.
This document defines OPTION_PREFIX_PROPERTY option that communicates
property of the prefix that is universally understood. This document
defines OPTION_PREFIX_CLASS option to communicate meta data of the
prefix that communicates the prefix's local significance.
This document discusses usage of OPTION_PREFIX_CLASS to request and
select prefixes with specific meta data via IA_PD and IA_NA as
defined in [RFC3633] and[RFC3315] respectively. This document
defines the behavior of the DHCPv6 server, the DHCPv6 prefix
requesting router and the DHCPv6 client to use OPTION_PREFIX_CLASS
option for requesting and selecting prefixes and addresses.
The network address can be configured via DHCPv6 as defined in
[RFC3315] or via Stateless Address Autoconfiguration (SLAAC) as
defined in [RFC4862], additional information of a prefix can be
provided via DHCPv6 or via IPv6 Router Advertisement (RA). The
information provided in the options defined in this document
OPTION_PREFIX_PROPERTY and OPTION_PREFIX_CLASS can be used for source
address selection. Communicated property and meta data information
about the prefix via IPv6 Router Advertisement (RA) will be dealt
with in separate document [I-D.korhonen-6man-prefix-properties].
1.1. Motivation
In this section motivation for class based prefix delegation that
qualifies the delegated prefix with additional class information is
described in the context of mobile networks and home networks. The
property information attached to a delegated prefix helps to
distinguish a delegated IPv6 prefix and selection of the prefix by
different applications using it.
Bhandari, et al. Expires January 16, 2014 [Page 3]
Internet-Draft DHCPv6 class based prefix July 2013
1.1.1. Mobile networks
In the mobile network architecture, there is a mobile router which
functions as a IP network gateway and provides IP connectivity to
mobile nodes. Mobile router can be the requesting router requesting
delegated IPv6 prefix using DHCPv6. Mobile router can assume the
role of DHCPv6 server for mobile nodes(DHCPv6 clients) attached to
it. A mobile node in mobile network architecture can be associated
with multiple IPv6 prefixes belonging to different domains for e.g.
home address prefix, care of address prefix as specified in
[RFC3775].
The delegated prefixes when seen from the mobile router perspective
appear to be like any other prefix, but each prefixes have different
meta data referred to as "Prefix Color" in the mobile networks. Some
delegated prefixes may be topologically local and some may be remote
prefixes anchored on a global anchor, but available to the local
anchor by means of tunnel setup in the network between the local and
global anchor. Some may be local with low latency characteristics
suitable for voice call break-out, some may have global mobility
support. So, the prefixes have different properties and it is
required for the application using the prefix to learn about this
property in order to use it intelligently. There is currently no
semantics in DHCPv6 prefix delegation that can carry this information
to specify properties of a delegated prefix. In this scenario, the
mobile router is unable to further delegate a longer prefix
intelligently based on properties of the prefix learnt. Neither is a
mobile device able to learn about the property of the prefix assigned
to influence source address selection. Example to determine if the
prefix is a home address or care of address.
1.1.2. Home networks
In a fixed network environment, the homenet CPE may also function as
both a DHCPv6 client (requesting the IA_PD(s)) and a DHCPv6 server
allocating prefixes from delegated prefix(es) to downstream home
network hosts. Some service providers may wish to delegate multiple
prefixes to the CPE for use by different services classes and traffic
types.
Motivations for this include:
o Using source prefix to identify the service class / traffic type
that is being transported. The source prefix may then reliably be
used as a parameter for differentiated services or other purposes.
E.g. [I-D.jiang-v6ops-semantic-prefix]
Bhandari, et al. Expires January 16, 2014 [Page 4]
Internet-Draft DHCPv6 class based prefix July 2013
o Using the specific source prefix as a host identifier for other
services. E.g. as an input parameter to a DHCPv4 over IPv6 server
[I-D.ietf-dhc-dhcpv4-over-ipv6]
To meet these requirements, when the CPE (functioning as a DHCPv6
server) receives an IA_NA or IA_TA request from a homenet host, a
mechanism is required so that the correct prefix for requested
service class can be selected for allocation. Likewise for DHCPv6
clients located in the homenet, a mechanism is necessary so that the
intended service class for a requested prefix can be signalled to the
DHCPv6 server.
1.2. Terminology
This document uses the terminology defined in [RFC2460], [RFC3315]
and [RFC3633].
1.3. 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].
2. Overview
This section defines prefix property and prefix class options in
IA_PD and IA_NA. This section defines the behavior of the delegating
router, the requesting router and the DHCPv6 client. It discusses
these options in the context of a DHCPv6 information request from a
DHCPv6 client to a DHCPv6 server.
2.1. Prefix Property and Class Options
The format of the DHCPv6 prefix property and prefix class options are
shown below.
Bhandari, et al. Expires January 16, 2014 [Page 5]
Internet-Draft DHCPv6 class based prefix July 2013
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_PREFIX_PROPERTY | option-length(2) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Properties |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code: OPTION_PREFIX_PROPERTY (TBD1)
option-length: 2
Properties: 16 bits maintained as
OPTION_PREFIX_PROPERTY in
IANA registered namespace.
Each value in the registry represents a property.
Multiple properties can be represented by bitwise
ORing of the individual property values in this
field.
Prefix Property Option
The individual property are maintained in OPTION_PREFIX_PROPERTY
values enumeration explained in Section Section 6.1.
Along with the OPTION_PREFIX_PROPERTY a meta data associated with the
prefix that is of local relevance is communicated using
OPTION_PREFIX_CLASS defined 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_PREFIX_CLASS | option-length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prefix Class |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code: OPTION_PREFIX_CLASS (TBD2)
option-length: 2
Prefix Class: 16 bit integer with the integer value
of local significance.
Prefix Class Option
2.2. Consideration for different DHCPv6 entities
Bhandari, et al. Expires January 16, 2014 [Page 6]
Internet-Draft DHCPv6 class based prefix July 2013
The model of operation of communicating prefixes to be used by a
DHCPv6 server is as follows. A requesting router requests prefix(es)
from the delegating router, as described in Section 2.2.1. A
delegating router is provided IPv6 prefixes to be delegated to the
requesting router. Examples of ways in which the delegating router
is provided these prefixes are:
o Configuration
o Prefix delegated via a DHCPv6 request to another DHCPv6 server
o Using a Authentication Authorization Accounting (AAA) protocol
like RADIUS [RFC2865]
The delegating router chooses prefix(es) for delegation, and responds
with prefix(es) to the requesting router along with additional
options in the allocated prefix as described in Section 2.2.2. The
requesting router is then responsible for the delegated prefix(es)
after the DHCPv6 REQUEST message exchange. For example, the
requesting router may create DHCPv6 server configuration pools from
the delegated prefix, and function as a DHCPv6 Server. When the
requesting router then receives a DHCPv6 IA_NA requests it can select
the address to be allocated based on the OPTION_PREFIX_CLASS option
received in IA_NA request or any of the other method as described in
Section 2.3.1.
2.2.1. Requesting Router Behavior for IA_PD allocation
DHCPv6 requesting router can request for prefixes in the following
ways:
o In the SOLICIT message within the IA_PD Prefix option, it MAY
include OPTION_PREFIX_CLASS requesting prefix delegation for the
specific class indicated in the OPTION_PREFIX_CLASS option. It
can include multiple IA_PD Prefix options to indicate it's
preference for more than one prefix class. The class of prefix it
requests is learnt via configuration or any other out of band
mechanism not defined in this document.
o In the SOLICIT message include an OPTION_ORO option with the
OPTION_PREFIX_CLASS option code to request prefixes from all the
classes that the DHCPv6 server can provide to this requesting
Router.
Bhandari, et al. Expires January 16, 2014 [Page 7]
Internet-Draft DHCPv6 class based prefix July 2013
The requesting router parses the OPTION_PREFIX_CLASS option in the
OPTION_IAPREFIX option area of the corresponding IA_PD Prefix option
in the ADVERTISE message. The Requesting router MUST then include
all or subset of the received class based prefix(es) in the REQUEST
message so that it will be responsible for the prefixes selected.
The requesting router parses and stores OPTION_PREFIX_PROPERTY if
received with the prefix.
2.2.2. Delegating Router Behavior for IA_PD allocation
If the Delegating router supports class based prefix allocation by
supporting the OPTION_PREFIX_CLASS option and it is configured to
assign prefixes from different classes, it selects prefixes for class
based prefix allocation in the following way:
o If requesting router includes OPTION_PREFIX_CLASS within the IA_PD
Prefix option, it selects prefixes to be offered from that
specific class.
o If requesting router includes OPTION_PREFIX_CLASS within
OPTION_ORO, then based on its configuration and policy it MAY
offer prefixes from multiple classes available.
The delegating router responds with an ADVERTISE message after
populating the IP_PD option with prefixes from different classes.
Along with including the IA_PD prefix options in the IA_PD option, it
MAY include the OPTION_PREFIX_CLASS option in the OPTION_IAPREFIX
option area of the corresponding IA_PD prefix option with the class
information of the prefix.
If neither the OPTION_ORO nor the IA_PD option in the SOLICIT message
include the OPTION_PREFIX_CLASS option, then the delegating router
MAY allocate the prefix as specified in [RFC3633] without including
the class option in the IA_PD prefix option in the response.
If OPTION_ORO option in the Solicit message includes the
OPTION_PREFIX_CLASS option code but the delegating router does not
support the solution described in this specification, then the
delegating router acts as specified in [RFC3633]. The requesting
router MUST in this case also fall back to the behavior specified in
[RFC3633].
Bhandari, et al. Expires January 16, 2014 [Page 8]
Internet-Draft DHCPv6 class based prefix July 2013
If both delegating and requesting routers support class-based prefix
allocation, but the delegating router cannot offer prefixes for any
other reason, it MUST respond to requesting router with appropriate
status code as specified in [RFC3633]. For e.g., if no prefixes are
available in the specified class then the delegating router MUST
include the status code NoPrefixAvail in the response message.
In addition if the delegating router has additional property
associated with the prefix it will be provided in
OPTION_PREFIX_PROPERTY option.
2.2.3. DHCPv6 Client Behavior for IA_NA allocation
DHCPv6 client MAY request for an IA_NA address allocation from a
specific prefix class in the following way:
o In the SOLICIT message within the IA_NA option, it MAY include the
OPTION_PREFIX_CLASS requesting address to be allocated from a
specific class indicated in that option. The class information to
be requested can be learnt via configuration or any other out of
band mechanism not described in this document.
If DHCPv6 client receives OPTION_PREFIX_CLASS, OPTION_PREFIX_PROPERTY
options in the IAaddr-options area of the corresponding IA_NA but
does not support one or both of these options, it SHOULD ignore the
received option(s).
2.2.4. DHCPv6 Server Behavior for IA_NA allocation
The DHCPv6 server parses OPTION_PREFIX_CLASS option received and when
it supports allocation within the requested OPTION_PREFIX_CLASS
responds with an ADVERTISE message after populating the IA_NA option
with address information from the requested prefix class. Along with
including the IA Address options in the IA_NA option, it also
includes the OPTION_PREFIX_CLASS option in the corresponding IAaddr-
options area.
Even though the IA_NA option in the SOLICIT message does not include
the OPTION_PREFIX_CLASS option, based on local policies, the DHCP
server MAY select a default OPTION_PREFIX_CLASS value for the client
and then SHOULD include the OPTION_PREFIX_CLASS option in the IAaddr-
options area of the corresponding IA_NA it sends to the client. If
both DHCP client and server support class based address allocation,
but the DHCP server cannot offer addresses in the specified Usage
class then the DHCP server MUST include the status code NoAddrsAvail
(as defined in [RFC3315]) in the response message. If the DHCP
server cannot offer addresses for any other reason, it MUST respond
to client with appropriate status code as specified in [RFC3315]. In
Bhandari, et al. Expires January 16, 2014 [Page 9]
Internet-Draft DHCPv6 class based prefix July 2013
addition if the server has additional property associated with the
prefix by means of configuration or learnt from DHCPv6 prefix
delegation or derived via any other means it MUST be sent as
OPTION_PREFIX_PROPERTY option.
2.3. Usage
Class based prefix delegation can be used by the requesting router to
configure itself as a DHCPv6 server to serve its DHCPv6 clients. It
can allocate longer prefixes from a delegated shorter prefix it
received, for serving IA_NA and IA_PD requests. Prefix property and
class can be used for source address selection by applications using
the prefix for communication.
2.3.1. Class based prefix and IA_NA allocation
The requesting router can use the delegated prefix(es) from different
classes (for example "video" (1), "guest"(2), "voice" (3) etc), for
assigning the IPv6 addresses to the end hosts through DHCPv6 IA_NA
based on a preconfigured mapping with OPTION_PREFIX_CLASS option, the
following conditions MAY be observed:
o It MAY have a pre-configured mapping between the prefix class and
OPTION_USER_CLASS option received in IA_NA.
o It MAY match the OPTION_PREFIX_CLASS if the IA_NA request received
contains OPTION_PREFIX_CLASS.
o It MAY have a pre-configured mapping between the prefix class and
the client DUID received in DHCPv6 message.
o It MAY have a pre-configured mapping between the prefix class and
its network interface on which the IA_NA request was received.
The requesting router playing the role of a DHCPv6 server can
ADVERTISE IA_NA from a class of prefix(es) thus selected.
2.3.2. Class based prefix and IA_PD allocation
If the requesting router, receives prefix(es) for different classes
(for example "video"(1), "guest"(2), "voice"(3) etc), it can use
these prefix(es) for assigning the longer IPv6 prefixes to requesting
routers it serves through DHCPv6 IA_PD by assuming the role of
delegating router, its behavior is explained in Section 2.2.2.
2.3.3. Class based prefix and SLAAC
Bhandari, et al. Expires January 16, 2014 [Page 10]
Internet-Draft DHCPv6 class based prefix July 2013
DHCPv6 IA_NA and IPv6 Stateless Address Autoconfiguration (SLAAC as
defined in [RFC4862]) are two ways by IPv6 addresses can be
dynamically assigned to end hosts. Making SLAAC class aware is
outside the scope of this document, it is specified in
[I-D.korhonen-6man-prefix-properties].
2.3.4. Class based prefix and applications
Applications within a host can do source address selection based on
the class of the prefix learnt in OPTION_PREFIX_PROPERTY and
OPTION_PREFIX_CLASS using rules defined in [RFC6724]. The internal
data structure and interface for source address selection used by
application to choose source prefix with specific property and class
in a host is beyond the scope of this document.
3. Example Application
3.1. Mobile gateway example
The following sub-sections provide examples of class based prefix
delegation and how it is used in a mobile network. Each of the
examples will refer to the below network:
The example network consists of :
Mobile Gateway It is network entity anchoring IP traffic in the
mobile core network. This entity allocates an IP address which is
topologically valid in the mobile network and may act as a mobility
anchor if handover between mobile and Wi-Fi is supported.
Mobile Nodes (MN) A host or router that changes its point of
attachment from one network or subnetwork to another. A mobile node
may change its location without changing its IP address; it may
continue to communicate with other Internet nodes at any location
using its (constant) IP address, assuming link-layer connectivity to
a point of attachment is available.
Access Point (AP) A wireless access point, identified by a MAC
address, providing service to the wired network for wireless nodes.
Access Router (AR) An IP router residing in an access network and
connected to one or more Access Point(AP)s. An AR offers IP
connectivity to MNs.
WLAN controller (WLC) The entity that provides the centralized
forwarding, routing function for the user traffic.
Bhandari, et al. Expires January 16, 2014 [Page 11]
Internet-Draft DHCPv6 class based prefix July 2013
_----_ _----_ _----_
_( )_ _( )_ _( )_
(Operator-1) (Operator-2) (Operator-3)
(_ _) (_ _) (_ _)
-+-- -+-- '-+--'
+--------+ +--------+ +--------+
| Mobile | | Mobile | | Mobile |
|gateway | |gateway | |gateway |
+--------+ +--------+ +--------+
| | |
+-------------. | .-------------+
| | |
| | |
| | |P1:"global-anchor"(1)
| | |
+--------+ _----_
+---+ | |P2:"local-breakout"(2)_( )_
|AAA|. . . . . . . | Access |---------------------( Internet )
+---+ | Aggreg |-----------+ (_ _)
| Gateway| P3:"guest"| '----'
+--------+ |
| | +----- Guest Access
| | Network
| +-------------+
| |
| +-----+
| | AR |
+-----+ +-----+
| WLC | * ---------*
| | ( LAN )
+-----+ * ---------*
/ \ / \
+----+ +----+ +----+ +----+
|WiFi| |WiFi| |WiFi| |WiFi|
| AP | | AP | | AP | | AP |
+----+ +----+ +----+ +----+
. .
/ \ / \
MN1 MN2 MN3 MN4(guest)
Figure 1: Example mobile network
Bhandari, et al. Expires January 16, 2014 [Page 12]
Internet-Draft DHCPv6 class based prefix July 2013
3.1.1. Class based prefix delegation
The Access Aggregation Gateway requests for Prefix delegation from
Mobile gateway and associates the prefix received with class "global-
anchor"(1). The Access Aggregation Gateway is preconfigured to
provide prefixes from the following classes: "global-anchor" (1),
"local-breakout"(2), "guest"(3). It has a preconfigured policy to
advertise prefixes to requesting routers and mobile nodes based on
the service class supported by the service provider for the
requesting device. In the example mobile network, the Access
Router(AR) requests class based prefix allocation by sending a DHCPv6
SOLICIT message and include OPTION_PREFIX_CLASS in the OPTION_ORO.
The Access Router (AR) receives an advertise with following prefixes
in the IA_PD option:
1. P1: IA_PD Prefix option with a prefix 3001:1::/64 containing
OPTION_PREFIX_CLASS set to "global-anchor"(1)
2. P2: IA_PD Prefix option with a prefix 3001:2::/64 containing
OPTION_PREFIX_CLASS set to "local-breakout"(2)
3. P3: IA_PD Prefix option with a prefix 3001:3::/64 containing
OPTION_PREFIX_CLASS set to "guest"(3)
It sends a REQUEST message with all of above prefixes and receives a
REPLY message with prefixes allocated for each of the requested
class.
3.1.2. IPv6 address assignment from class based prefix
When the Access Router(AR) receives a DHCPv6 SOLICIT requesting IA_NA
from the mobile node that has mobility service enabled, it offers an
IPv6 address from the prefix class "global-anchor"(1). For MN3 it
advertises 3001:1::1 as the IPv6 address in OPTION_IAADDR in response
to the IA_NA request.
The Mobile Node(MN4) Figure 1 sends a DHCPv6 SOLICIT message
requesting IA_NA address assignment with OPTION_USER_CLASS option
containing the value "guest" towards the CPE. The Access Router(AR)
assumes the role of the DHCPv6 server and sends an ADVERTISE to the
MN with OPTION_IA_NA containing an IPv6 address in OPTION_IAADDR from
the "guest"(3) class. The IPv6 address in the OPTION_IAADDR is set
to 3001:3::1. The "guest" class can also be distinguished based on a
preconfigured interface or SSID advertised for MNs connecting to it.
When the Access Aggregation Gateway receives a DHCPv6 SOLICIT
requesting IA_NA from MNs through WLC and it has a preconfigured
Bhandari, et al. Expires January 16, 2014 [Page 13]
Internet-Draft DHCPv6 class based prefix July 2013
profile to provide both local-breakout Internet access and global-
anchor, it offers an IPv6 address from the class "local-breakout" (2)
and "global-anchor"(1). For MN1 it advertises 3001:2::1 and
3001:1::2 as the IPv6 address in OPTION_IAADDR in response to the
IA_NA request. Applications within MN1 can choose to use the
appropriate prefix based on the mobility enabled or local-breakout
property attached to the prefix based on source address selection
policy.
The prefixes that are globally anchored and hence have mobility can
be advertised with OPTION_PREFIX_PROPERTY set to 0x0002 to convey
that the prefix provides network based mobility as listed in
Section 6.1. If the prefix also provides security guarantees
OPTION_PREFIX_PROPERTY can be set to 0x000A to indicate mobility and
security guarantees by bitwise ORing of both the properties.
3.2. Homenet Example
The following sub-section describes an example of class based prefix
delegation in a home network environment. The network consists of
the following elements:
o Home Gateway (HGW) device: a routing device located in the
customer's premises that provides connectivity between the
customer and the service provider. In this example, the HGW is
functioning as both a DHCP client towards the service provider's
DHCP infrastructure and a DHCP server towards hosts located in the
home network.
o IPv6 Set Top Box (STB): A dedicated, IPv6 attached, video on
demand device.
o IPv6 PC: An IPv6 attached personal computer
o Delegating Router: The router in the ISPs network acting as a DHCP
server for the IA_PD request.
o ISP Video On Demand (ISP-VOD) service: An ISP provided service
offering unicast based streaming video content to subscribers.
o Video On Demand (VOD) service: A server providing unicast based
streaming video content to subscribers
o On demand Video Application: Application hosted on the IPv6 PC
o Application Central: Application server hosted in the Internet
that the On demand Video Application communicates with to access
VOD service
Bhandari, et al. Expires January 16, 2014 [Page 14]
Internet-Draft DHCPv6 class based prefix July 2013
+-----------+ _----+----_ +----------+
|Application| _( )_ | Video on |
|central |-( Internet )---| Demand |
| | (_ _) | Service |
+-----------+ '----+----' +----------+
|
_----+----_ +----------+ \
_( )_ |ISP Video | \
(Service Provider)--| on Demand| \
(_ Network _) | Service | | ISP
'----+----' +----------+ | Network
| |
+------+-----+ |
| Delegating | |
| Router | |
+------+-----+ |
| |
| Customer |
| Internet connection /
| /
| /
+------+--------+ ^ \
| IPv6 | | DHCPv6 Client \
| Home gateway | \
| Device (CPE) | | DHCPv6 Server |
+------+--------+ v | Home
| | Network
Home Network | |
+-----+-------+ |
| | |
+----+-----+ +-----+----+ |
|IPv6 Host | |IPv6 Host | |
| (Set top | | (PC) | DHCPv6 Clients /
| box) | | | /
+----------+ +----------+ /
Simple home network with Data and Video devices
3.2.1. Class based prefix delegation to the HGW
In this example, three different services are being run on the same
network. The service provider wishes that traffic is sourced from
different prefixes by the home network clients
[I-D.jiang-v6ops-semantic-prefix]. The HGW (requesting router) has
been configured to request prefix delegation from the ISPs delegating
router with the usage classes "video" (1) and "internet"(2) and
"video-app" (3) the meaning of these being of relevance to the ISP
Bhandari, et al. Expires January 16, 2014 [Page 15]
Internet-Draft DHCPv6 class based prefix July 2013
operating this and application that are configured out of band to
utilize it.
The delegating router is preconfigured to advertise prefixes with
these service classes. The HGW sends three IA_PD options within the
SOLICIT message, one with OPTION_PREFIX_CLASS "video" (1), the second
with "internet" (2) and a third with "video-app" (3). The HGW
receives an advertise with the following prefixes in the IA_PD
option:
1. P1: IA_PD Prefix option with a prefix 3001:5::/56 containing
OPTION_PREFIX_CLASS set to "video" (1) with OPTION_PREFIX_PROPERTY
set to 0x0001 indicating there is no internet reach
2. P2: IP_PD Prefix option with a prefix 3001:6::/56 containing
OPTION_PREFIX_CLASS set to "internet" (2)
3. P3: IP_PD Prefix option with a prefix 3001:7::/56 containing
OPTION_PREFIX_CLASS set to "video-app" (3) with property set to
0x0040 indicating the prefix provides Internet service SLA
It sends a REQUEST message with all of the above prefixes and
receives a REPLY message with prefixes allocated for each of the
requested classes. The HGW then configures a /64 prefix from each of
the delegated prefixes on its LAN interface [RFC6204] and sends out
router advertisements (RAs) with the "M" and "O" bits set.
3.2.2. IPv6 Assignment to Homenet hosts using stateful DHCPv6
1. STB sends a DHCPv6 SOLICIT message with the OPTION_PREFIX_CLASS
option set to "video" (1) within the IA_NA. The HGW checks the
requested prefix class against the available prefixes it has been
delegated and advertises 3001:5::1 to the STB. The STB then
configures this address on its LAN interface and uses it for
sourcing requests to the VOD service.
2. The PC sends a DHCPv6 SOLICIT message requesting for IA_NA with
the OPTION_PREFIX_CLASS option in ORO indicating support for
prefix class. The HGW checks the available prefixes it has been
delegated and advertises IA_NA from P1 (3001:5:2 with property
set to 0x0001) , P2 (3001;6::1) and P3 (3001:7::1) to the PC or
in absence of OPTION_PREFIX_CLASS in the solicit HGW is
preconfigured to assign from the "internet"(2) class as the
default. The PC then configures these addresses on its LAN
interface and uses it for sourcing requests to the Internet.
3. The On demand Video Application on the PC communicates with its
well known Application Central using the "internet" prefix and is
Bhandari, et al. Expires January 16, 2014 [Page 16]
Internet-Draft DHCPv6 class based prefix July 2013
directed to use "video-app" prefix if available based on
agreement between service provider and on demand video
application service provider. The On demand Video Application
then connects using the address assigned from P3 that will offer
better experience based on the SLA between the providers.
4. If the homenet hosts use SLAAC prefix delegation with the class
will use the options and procedure defined in
[I-D.korhonen-6man-prefix-properties]
4. Acknowledgements
The authors would like to acknowledge review and guidance received
from Frank Brockners, Wojciech Dec, Richard Johnson, Erik Nordmark,
Hemant Singh, Mark Townsley, Ole Troan, Bernie Volz, Maciek
Konstantynowicz
5. Contributors
Authors would like to thank contributions to use cases and text for
various sections received from Sindhura Bandi.
6. IANA Considerations
IANA is requested to assign an option code to OPTION_PREFIX_PROPERTY
(TBD1) and OPTION_PREFIX_CLASS (TBD2) from the "DHCPv6 and DHCPv6
options" registry (http://www.iana.org/assignments/dhcpv6-parameters/
dhcpv6-parameters.xml).
6.1. OPTION_PREFIX_PROPERTY values
IANA is requested to reserve and maintain registry of
OPTION_PREFIX_PROPERTY values and manage allocation of values as per
as per policy defined in [RFC5226] with IETF assigned values
requiring IETF consensus, RFC Required policy, any other values other
than the ones listed below are not valid.
1. 0x0001 The prefix cannot be used to reach the Internet
2. 0x0002 The prefix provides network based mobility
3. 0x0004 The prefix requires authentication
4. 0x0008 The prefix is assigned on an interface that provides
security guarantees
5. 0x0010 Usage is charged
Bhandari, et al. Expires January 16, 2014 [Page 17]
Internet-Draft DHCPv6 class based prefix July 2013
6. 0x0020 The prefix provides multi-homed redundancy
7. 0x0040 The prefix provides Internet service SLA, based on
associated OPTION_PREFIX_CLASS
8. 0x0080 Unassigned
9. 0x0100 Unassigned
10. 0x0200 Unassigned
11. 0x0400 Unassigned
12. 0x0800 Unassigned
13. 0x1000 Unassigned
14. 0x2000 Unassigned
15. 0x4000 Unassigned
16. 0x8000 Unassigned
7. Security Considerations
Security issues related to DHCPv6 which are described in section 23
of [RFC3315] and [RFC3633] apply for scenarios mentioned in this
draft as well.
8. Change History (to be removed prior to publication as an RFC)
Changes from -00 to -01
a. Modified motivation section to focus on mobile networks
b. Modified example with a mobile network and class based prefix
delegation in it
Changes from -01 to -02
a. Modified option format to be enumerated values
b. Added IANA section to request managing of registry for the
enumerated values
c. Added initial values for the class
Bhandari, et al. Expires January 16, 2014 [Page 18]
Internet-Draft DHCPv6 class based prefix July 2013
d. Added section for applications to select address with a specific
property
Changes from -02 to -03
a. Added server behaviour for IA_NA and IA_PD allocation
b. Added Class based Information-Request usage
Changes from -03 to -04
a. Added homenet use case
b. Split usage class into a fixed IANA maintained properties
registry and a prefix class
Changes from -04 to -05
a. Added on demand video application use case and modified the
example section
b. Added additional properties and reference for SLAAC/ND procedure
9. References
9.1. Normative References
[I-D.ietf-dhc-dhcpv4-over-ipv6]
Cui, Y., Wu, P., Wu, J., and T. Lemon, "DHCPv4 over IPv6
Transport", draft-ietf-dhc-dhcpv4-over-ipv6-06 (work in
progress), March 2013.
[I-D.jiang-v6ops-semantic-prefix]
Jiang, S., Sun, Q., Farrer, I., and Y. Bo, "A Framework
for Semantic IPv6 Prefix", draft-jiang-v6ops-semantic-
prefix-03 (work in progress), May 2013.
[I-D.korhonen-6man-prefix-properties]
Korhonen, J., Patil, B., Gundavelli, S., Seite, P., and D.
Liu, "IPv6 Prefix Properties", draft-korhonen-6man-prefix-
properties-02 (work in progress), July 2013.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998.
Bhandari, et al. Expires January 16, 2014 [Page 19]
Internet-Draft DHCPv6 class based prefix July 2013
[RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson,
"Remote Authentication Dial In User Service (RADIUS)", RFC
2865, June 2000.
[RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
and M. Carney, "Dynamic Host Configuration Protocol for
IPv6 (DHCPv6)", RFC 3315, July 2003.
[RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
Host Configuration Protocol (DHCP) version 6", RFC 3633,
December 2003.
[RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support
in IPv6", RFC 3775, June 2004.
[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
Address Autoconfiguration", RFC 4862, September 2007.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[RFC6204] Singh, H., Beebee, W., Donley, C., Stark, B., and O.
Troan, "Basic Requirements for IPv6 Customer Edge
Routers", RFC 6204, April 2011.
[RFC6724] Thaler, D., Draves, R., Matsumoto, A., and T. Chown,
"Default Address Selection for Internet Protocol Version 6
(IPv6)", RFC 6724, September 2012.
9.2. Informative References
[RFC2629] Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629,
June 1999.
[RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC
Text on Security Considerations", BCP 72, RFC 3552, July
2003.
Authors' Addresses
Shwetha Bhandari
Cisco Systems
Cessna Business Park, Sarjapura Marathalli Outer Ring Road
Bangalore, KARNATAKA 560 087
India
Email: shwethab@cisco.com
Bhandari, et al. Expires January 16, 2014 [Page 20]
Internet-Draft DHCPv6 class based prefix July 2013
Gaurav Halwasia
Cisco Systems
Cessna Business Park, Sarjapura Marathalli Outer Ring Road
Bangalore, KARNATAKA 560 087
India
Phone: +91 80 4426 1321
Email: ghalwasi@cisco.com
Sri Gundavelli
Cisco Systems
170 West Tasman Drive
San Jose, CA 95134
USA
Email: sgundave@cisco.com
Hui Deng
China Mobile
53A, Xibianmennei Ave., Xuanwu District
Beijing 100053
China
Email: denghui02@gmail.com
Laurent Thiebaut
Alcatel-Lucent
France
Email: laurent.thiebaut@alcatel-lucent.com
Jouni Korhonen
Renesas Mobile
Linnoitustie 6
FIN-02600 Espoo
Finland
Email: jouni.nospam@gmail.com
Bhandari, et al. Expires January 16, 2014 [Page 21]
Internet-Draft DHCPv6 class based prefix July 2013
Ian Farrer
Deutsche Telekom AG
GTN-FM4, Landgrabenweg 151
Bonn 53227
Bonn 53227
Email: ian.farrer@telekom.de
Bhandari, et al. Expires January 16, 2014 [Page 22]
