Network Working Group B. Lourdelet
Internet-Draft W. Dec, Ed.
Intended status: Standards Track Cisco Systems, Inc.
Expires: September 15, 2011 B. Sarikaya
Huawei USA
G. Zorn
Network Zen
D. Miles
Alcatel-Lucent
March 14, 2011
RADIUS attributes for IPv6 Access Networks
draft-ietf-radext-ipv6-access-04.txt
Abstract
This document specifies additional IPv6 RADIUS attributes useful in
residential broadband network deployments. The attributes, which are
used for authorization and accounting, enable assignment of a host
IPv6 address and IPv6 DNS server address via DHCPv6; assignment of an
IPv6 route announced via router advertisement, and assignment of a
named IPv6 delegated prefix pool.
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 15, 2011.
Copyright Notice
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Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Deployment Scenarios . . . . . . . . . . . . . . . . . . . . . 4
2.1. IPv6 Address Assignment . . . . . . . . . . . . . . . . . 5
2.2. Recursive DNS Servers . . . . . . . . . . . . . . . . . . 6
2.3. IPv6 Route Information . . . . . . . . . . . . . . . . . . 6
2.4. Delegated IPv6 Prefix Pool . . . . . . . . . . . . . . . . 6
3. Attributes . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.1. Framed-IPv6-Address . . . . . . . . . . . . . . . . . . . 7
3.2. DNS-Server-IPv6-Address . . . . . . . . . . . . . . . . . 8
3.3. Route-IPv6-Information . . . . . . . . . . . . . . . . . . 9
3.4. Delegated-IPv6-Prefix-Pool . . . . . . . . . . . . . . . . 10
3.5. Table of attributes . . . . . . . . . . . . . . . . . . . 10
4. Diameter Considerations . . . . . . . . . . . . . . . . . . . 10
5. Security Considerations . . . . . . . . . . . . . . . . . . . 11
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
8.1. Normative References . . . . . . . . . . . . . . . . . . . 11
8.2. Informative References . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12
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1. Introduction
In IPv6 deployments DHCPv6 and/or ICMPv6 Router Advertisements can be
used to convey configuration information by a NAS towards accessing
hosts. Such information typically needs to be provisioned on the NAS
and may be done so on a per host or user basis using the AAA process.
This document specifies additional RADIUS attributes used to support
configuration of DHCPv6 and/or ICMPv6 parameters on a per-user basis.
The attributes, which complement those defined in [RFC3162] and
[RFC4818], support the following:
o The assignment or accounting of specific IPv6 addresses assigned
to hosts. While [RFC3162] permits an IPv6 address to be specified
via the combination of the Framed-Interface-Id and Framed-IPv6-
Prefix attributes, this separation is more natural for use with
IPv6CP than it is for use with DHCPv6, and the use of a single
IPv6 address attribute makes for easier processing of accounting
records.
o Assignment of an IPv6 DNS server address, via DHCPv6 or [RFC5006]
o Configuration of a route to be passed to the host via Router
Advertisement [RFC4191] or other similar mechanisms (eg DHCPv6)
o The assignment of a named delegated prefix pool for use with "IPv6
Prefix Options for DHCPv6" [RFC3633]
2. Deployment Scenarios
A common broadband network scenario is illustrated in Figure 1. It
is composed of a IP Routing Residential Gateway (RG) or host, a Layer
2 Access-Node (e.g. a DSLAM), one or more IP Network Access Servers
(NASes), and an AAA server. The RG or host are expected to be multi
homed to both NASes. Layer 2 Connectivity between the host and NAS
can be either via PPPoE or IP over Ethernet, and established
dynamically.
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+-----+
(Radius) | AAA |
...........>| |
. +--+--+
v ^
+---+---+ .
| NAS | .(Radius)
| | .
+---+---+ v
+------+ | +---+---+
+------+ | AN | | | NAS |
| RG/ +-------| +-----------+----------+ |
| host | | | | |
+------+ (DSL) +------+ (Ethernet) +-------+
Figure 1
In this scenario the NASes may embed a DHCPv6 server to handle DHCPv6
requests issued by RGs/hosts, as well as acting as a router providing
Router Advertisements. The RADIUS server authenticates each RG/host
and returns to the NAS attributes used for authorization and
accounting. These attributes can include a host IPv6 address to be
configured via DHCPv6; the IPv6 address of a DNS server to configured
via DHCPv6 or router advertisement; the name of a prefix pool to be
used for DHCPv6 Prefix Delegation; or IPv6 routes to be announced to
the host.
The following sub-sections discuss how these uses in more detail.
2.1. IPv6 Address Assignment
DHCPv6 [RFC3315] provides a mechanism to assign one or more or non-
temporary IPv6 addresses to hosts. To provide a DHCPv6 server
residing on a NAS with one or more IPv6 addresses to be assigned,
this document specifies the Framed-IPv6-Address Attribute.
Since DHCPv6 can be deployed on the same network as ICMPv6 stateless
(SLAAC) [RFC4862], it is possible that the NAS will require both
stateful and stateless configuration information. Therefore it is
possible for the Framed-IPv6-Address, Framed-IPv6-Prefix and Framed-
Interface-Id attributes [RFC3162] to be included within the same
packet. To avoid ambiguity, the Framed-IPv6-Address attribute is
only used for authorization and accounting of DHCPv6-assigned
addresses and the Framed-IPv6-Prefix and Framed-Interface-Id
attributes are used for authorization and accounting of addresses
assigned via SLAAC.
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2.2. Recursive DNS Servers
DHCPv6 provides an option for recursive DNS servers to hosts, as does
ICMPv6 with Router Advertisements supporting the experimental
[RFC5006] option. Existing IETF RADIUS attributes convey DNS as 32-
bit IPv4 addresses and cannot support a 128-bit IPv6 address. This
document specifies the RADIUS attribute to convey a list of IPv6 DNS
Recursive name server addresses, from an AAA server, which can that
can be conveyed by a NAS to a host.
2.3. IPv6 Route Information
An IPv6 Route Information option, defined in [RFC4191] is intended to
be used to inform a host connected to the NAS that a specific route
is reachable via the NAS. This is particularly desirable in cases
where the RG or host are multi-homed to different NASes as shown in
Figure 1.
This document specifies the RADIUS attribute that allows the AAA
system to provision the announcement by the NAS of a specific Route
Information Option to an accessing host. The NAS may advertise this
route using the method defined in [RFC4191] or using other equivalent
methods.
The distinction and separation between this attribute and the Framed-
IPv6-Route attribute defined in [RFC3162] is needed due to the need
to have the information carried by this attribute advertised (in
binary format as per RFC4191) to an attaching client, rather than
intended for the NAS itself.
2.4. Delegated IPv6 Prefix Pool
DHCPv6 Prefix Delegation [RFC3633] involves a delegating router
selecting a prefix and delegating it on a temporary basis to a
requesting router. The delegating router may implement a number of
strategies as to how it chooses what prefix is to be delegated to a
requesting router, one of them being the use of a local named prefix
pool. The Delegated-IPv6-Prefix-Pool Attribute allows the RADIUS
server to convey a prefix pool name to a NAS hosting a DHCPv6-PD
server and acting as a delegated router.
Since DHCPv6 Prefix Delegation can conceivably be used on the same
network as SLAAC, it is possible for the Delegated-IPv6-Prefix-Pool
and Framed-IPv6-Pool attributes to be included within the same
packet. To avoid ambiguity in this scenario, use of the Delegated-
IPv6-Prefix-Pool attribute should be restricted to authorization and
accounting of prefix pools used in DHCPv6 Prefix Delegation and the
Framed-IPv6-Pool attribute should be used for authorization and
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accounting of prefix pools used in SLAAC.
3. Attributes
The fields shown in the diagrams below are transmitted from left to
right.
3.1. Framed-IPv6-Address
This Attribute indicates an IPv6 Address that is assigned to the NAS-
facing interface of the RG/host. It MAY be used in Access-Accept
packets, and MAY appear multiple times. It MAY be used in an Access-
Request packet as a hint by the NAS to the server that it would
prefer these IPv6 address(es), but the server is not required to
honor the hint. Since it is assumed that the NAS will add a route
corresponding to the address, it is not necessary for the server to
also send a host Framed-IPv6-Route attribute for the same address.
This Attribute can be used by a DHCPv6 process on the NAS to assign a
unique IPv6 address to the RG/host.
A summary of the Framed-IPv6-Address Attribute format is shown 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Address
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Address (cont)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Address (cont)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Address (cont)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Address (cont.) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
TBA1 for Framed-IPv6-Address
Length
18
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Address
The IPv6 address field contains a 128-bit IPv6 address.
3.2. DNS-Server-IPv6-Address
The DNS-Server-IPv6-Address Attribute contains the IPv6 address of a
recursive DNS server. This attribute MAY be included multiple times
in Access-Accept packets, when the intention is for a NAS to announce
more than one recursive DNS address to an RG/host. The same order of
the attributes is expected to be followed in the announcements to the
client.
The content of this attribute can be inserted in a DHCPv6 option as
specified in [RFC3646] or mapped option.
A summary of the DNS-Server-IPv6-Address Attribute format is given
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Address
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Address (cont)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Address (cont)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Address (cont)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Address (cont.) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
TBA2 for DNS-Server-IPv6-Address
Length
18
Address
The 128-bit IPv6 address of a DNS server.
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3.3. Route-IPv6-Information
This Attribute specifies a prefix (and corresponding route) to be
authorized for announcement towards the user by the NAS, with the
reachable by means of routing towards the NAS. It is used in the
Access-Accept packet and can appear multiple times. It may also be
used in the Access-Request packet as hint to the server.
A summary of the Route-IPv6-Information attribute format is shown
below. The route information option defined in [RFC4191] is captured
in this and following two attributes.
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 | Reserved | Prefix-Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. Prefix (variable) .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
TBA3 for Route-IPv6-Information
Length
Length in bytes. At least 4 and no larger than 20; typically 12
or less.
Prefix Length
The length of the prefix, in bits; at least 0 and no more than
128; typically 64 or less.
Prefix
Variable-length field containing an IP prefix. The Prefix Length
field contains the number of valid leading bits in the prefix.
The bits in the prefix after the prefix length (if any) up to the
byte boundary are reserved and MUST be initialized to zero by the
sender and ignored by the receiver.
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3.4. Delegated-IPv6-Prefix-Pool
This Attribute contains the name of an assigned pool that SHOULD be
used to select an IPv6 delegated prefix for the user. If a NAS does
not support multiple prefix pools, the NAS MUST ignore this
Attribute.
A summary of the Delegated-IPv6-Prefix-Pool Attribute format is shown
below. The fields are transmitted from left to right.
0 1 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | String...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
TBA4 for Delegated-IPv6-Prefix-Pool
Length
Length in bytes. At least 4.
String
The string field contains the name of an assigned IPv6 prefix pool
configured on the NAS. The field is not NULL (hex 00) terminated.
3.5. Table of attributes
The following table provides a guide to which attributes may be found
in which kinds of packets, and in what quantity.
Request Accept Reject Challenge Accounting # Attribute
Request
0+ 0+ 0 0 0+ TBA1 Framed-IPv6-Address
0+ 0+ 0 0 0+ TBA2 DNS-Server-IPv6-Address
0 0+ 0 0 0+ TBA3 Route-IPv6-Information
0 0-1 0 0 0-1 TBA4 Delegated-IPv6-Prefix-Pool
4. Diameter Considerations
Given that the Attributes defined in this document are allocated from
the standard RADIUS type space (see Section 6), no special handling
is required by Diameter entities.
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5. Security Considerations
This document describes the use of RADIUS for the purposes of
authentication, authorization and accounting in IPv6-enabled
networks. In such networks, the RADIUS protocol may run either over
IPv4 or over IPv6. Known security vulnerabilities of the RADIUS
protocol apply to the attributes defined in this document. Since
IPSEC is natively defined for IPv6, it is expected that running
RADIUS implementations supporting IPv6 may want to run over IPSEC.
Where RADIUS is run over IPSEC and where certificates are used for
authentication, it may be desirable to avoid management of RADIUS
shared secrets, so as to leverage the improved scalability of public
key infrastructure.
6. IANA Considerations
This document requires the assignment of three new RADIUS Attribute
Types in the "Radius Types" registry (currently located at
http://www.iana.org/assignments/radius-types for the following
attributes:
o Framed-IPv6-Address
o DNS-Server-IPv6-Address
o Route-IPv6-Information
o Delegated-IPv6-Prefix-Pool
7. Acknowledgements
The authors would like to thank Bernard Aboba, Alfred Hines, Alan
DeKok, Peter Deacon, and Mark Smith for their help and comments in
reviewing this document.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
Address Autoconfiguration", RFC 4862, September 2007.
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8.2. Informative References
[RFC3162] Aboba, B., Zorn, G., and D. Mitton, "RADIUS and IPv6",
RFC 3162, August 2001.
[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.
[RFC3646] "".
[RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and
More-Specific Routes", RFC 4191, November 2005.
[RFC4818] Salowey, J. and R. Droms, "RADIUS Delegated-IPv6-Prefix
Attribute", RFC 4818, April 2007.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
September 2007.
[RFC5006] Jeong, J., Park, S., Beloeil, L., and S. Madanapalli,
"IPv6 Router Advertisement Option for DNS Configuration",
RFC 5006, September 2007.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
Authors' Addresses
Benoit Lourdelet
Cisco Systems, Inc.
Village ent. GreenSide, Bat T3,
400, Av de Roumanille,
06410 BIOT - Sophia-Antipolis Cedex
France
Phone: +33 4 97 23 26 23
Email: blourdel@cisco.com
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Wojciech Dec (editor)
Cisco Systems, Inc.
Haarlerbergweg 13-19
Amsterdam , NOORD-HOLLAND 1101 CH
Netherlands
Email: wdec@cisco.com
Behcet Sarikaya
Huawei USA
1700 Alma Dr. Suite 500
Plano, TX
US
Phone: +1 972-509-5599
Email: sarikaya@ieee.org
Glen Zorn
Network Zen
1310 East Thomas Street
Seattle, WA
US
Email: gwz@net-zen.net
David Miles
Alcatel-Lucent
L3 / 215 Spring St
Melbourne, Victoria 3000,
Australia
Phone:
Fax:
Email: David.Miles@alcatel-lucent.com
URI:
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