Network Working Group Dayong Guo
Internet Draft Sheng Jiang
Intended status: Standards Track Huawei Technologies Co., Ltd
R. Despres
RD-IPtech
Expires: April 25, 2011 Oct 18, 2010
RADIUS Attribute for 6rd
draft-guo-softwire-6rd-radius-attrib-00.txt
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Abstract
6rd is One of the most popular methods to provide both IPv4 and IPv6
connectivity services simultaneously during the IPv4/IPv6 co-existing
period. The DHCP 6rd option has been defined to configure 6rd CPE.
But in many networks, the configuration information may be stored in
AAA servers while user configuration is mainly from Broadband Network
Gateway (BNG) through DHC protocol. This document defines a RADIUS
attribute that carries 6rd configuration information from AAA server
to BNG.
Table of Contents
1. Introduction................................................3
2. Terminology.................................................3
3. 6rd Configuration with RADIUS................................3
4. Attributes..................................................4
4.1. 6rd Attribute..........................................4
4.2. Table of attributes.....................................5
5. Diameter Considerations......................................6
6. Security Considerations......................................6
7. IANA Considerations.........................................6
8. Acknowledgments.............................................6
9. Change Log [RFC Editor please remove]........................6
10. References.................................................7
10.1. Normative References...................................7
10.2. Informative References.................................7
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1. Introduction
Recently providers start to deploy IPv6 and consider how to transit
to IPv6. 6rd [RFC5969] is one of the most popular methods to provide
both IPv4 and IPv6 connectivity services simultaneously during the
IPv4/IPv6 co-existing period. 6rd is used to provide IPv6
connectivity service through legacy IPv4-only infrastructure. 6rd
adopt DHCP as auto-configuring protocol. The 6rd CPE extends DHCP
option to discover 6rd border relay and to configure IPv6 prefix and
address.
In many networks, user configuration information may be managed by
AAA servers, together with user Authentication, Authorization, and
Accounting (AAA). Current AAA servers communicate using the RADIUS
(Remote Authentication Dial In User Service, [RFC2865]) protocol.
In a fixed line broadband network, the Broadband Network Gateways
(BNGs) act as the access gateway of users (hosts or CPEs). The BNGs
are assumed to embed a DHCP server function that allows them to
locally handle any DHCP requests issued by hosts.
Since the 6rd configuration information is stored in AAA servers and
user configuration is mainly through DHC protocol between BNGs and
hosts. New RADIUS attributes are needed to propagate the information
from AAA servers to BNGs.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC2119 [RFC2119].
3. 6rd Configuration with RADIUS
The below Figure 1 illustrates how the RADIUS protocol and DHCP are
cooperated to provide users/hosts with 6rd configuration.
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User/host BNG AAA Server
| | |
|-------DHCPDISCOVER------>| |
| |---Request(6rd Attribute)--->|
| | |
| |<---Accept(6rd Attribute)----|
|<-------DHCPOFFER---------| |
| | |
|-------DHCPREQUEST------->| |
| (6rd Option) | |
|<--------DHCPACK----------| |
| (6rd option) | |
| | |
DHCP RADIUS
Figure 1: the cooperation between DHCP and RADIUS
BNGs act as a bridge between user and AAA server. First, a BNG
receives a user DHCPDISCOVER. It initiates the BNG to request
correspondent user authentication relevant from an AAA server using
RADIUS protocol. A 6rd request may be also sent in the same message.
If the user authentication is approved by the AAA server, an Accept
message is acknowledged with the 6rd Attribute, defined in the next
Section. After the BNG responds to the user with an Advertise
message, the user requests for a 6rd Option. Then, the BNG can reply
the user using DHCP protocol.
4. Attributes
This section defines 6rd attribute which is used in the 6rd scenario.
4.1. 6rd Attribute
The 6rd Attribute is structured as follows:
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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 | IPv4MaskLen | 6rdPrefixLen |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| 6rdPrefix |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 6rdBRIPv4Address(es) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type TBD
Length the length of the DHCP option in octets (22 octets
with one BR IPv4 address).
IPv4MaskLen The number of high-order bits that are identical
across all CE IPv4 addresses within a given 6rd
domain. This may be any value between 0 and 32.
Any value greater than 32 is invalid.
6rdPrefixLen The IPv6 Prefix length of the Service Provider's
6rd IPv6 prefix in number of bits. The
6rdPrefixLen MUST be less than or equal to 128.
6rdPrefix The Service Provider's 6rd IPv6 prefix represented
as a 16 octet IPv6 address. The bits after the
6rdPrefixlen number of bits in the prefix SHOULD
be set to zero.
6rdBRIPv4Address One or more IPv4 addresses of the 6rd Border
Relay(s) for a given 6rd domain.
4.2. 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+ TBD 6rd
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5. Diameter Considerations
This attribute is usable within either RADIUS or Diameter [RFC3588].
Since the Attributes defined in this document will be allocated from
the standard RADIUS type space, no special handling is required by
Diameter entities.
6. Security Considerations
In 6rd scenarios, the RADIUS protocol is run over IPv4. Known
security vulnerabilities of the RADIUS protocol are discussed in RFC
2607 [RFC2607], RFC 2865 [RFC2865], and RFC 2869 [RFC2869]. Use of
IPsec [RFC4301] for providing security when RADIUS is carried in IPv6
is discussed in RFC 3162 [RFC3162].
Security considerations for the Diameter protocol are discussed in
RFC 3588 [RFC3588].
7. IANA Considerations
This document requires the assignment of two new RADIUS Attribute
Types in the "Radius Types" registry (currently located at
http://www.iana.org/assignments/radius-types for the following
attributes:
o 6rd
IANA should allocate these numbers from the standard RADIUS
Attributes space using the "IETF Review" policy [RFC5226].
8. Acknowledgments
The authors would like to thank Maglione Roberta, Telecom Italia, for
valuable comments.
9. Change Log [RFC Editor please remove]
draft-guo-softwire-6rd-radiusattrib-00, renaming and deleting DS-lite
contents, 2010-10-18.
draft-guo-radext-softwire-concentrator-00, original version, 2010-07-
05.
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10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson,
"Remote Authentication Dial In User Service (RADIUS)", RFC
2865, June 2000.
[RFC3162] Aboba, B., Zorn, G., and D. Mitton, "RADIUS and IPv6", RFC
3162, August 2001.
[RFC3588] Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and J.,
Arkko, "Diameter Base Protocol", RFC 3588, September 2003.
[RFC4301] Kent, S. and K. Seo, "Security Architecture for the
Internet Protocol", RFC 4301, December 2005.
[RFC5226] T. Narten, H. Alvestrand, "Guidelines for Writing an IANA
Considerations Section in RFCs", RFC 5226, May 2008.
[RFC5969] Townsley W., et al., "IPv6 Rapid Deployment on IPv4
Infrastructures (6rd) -- Protocol Specification", RFC5969,
August 2010.
10.2. Informative References
[RFC2607] Aboba, B. and J. Vollbrecht, "Proxy Chaining and Policy
Implementation in Roaming", RFC 2607, June 1999.
[RFC2869] Rigney, C., Willats, W., and P. Calhoun, "RADIUS
Extensions", RFC 2869, June 2000.
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Author's Addresses
Dayong Guo
Huawei Technologies Co., Ltd
Huawei Building, No.3 Xinxi Rd.,
Shang-Di Information Industry Base, Hai-Dian District, Beijing 100085
P.R. China
Email: guoseu@huawei.com
Sheng Jiang
Huawei Technologies Co., Ltd
Huawei Building, No.3 Xinxi Rd.,
Shang-Di Information Industry Base, Hai-Dian District, Beijing 100085
P.R. China
Email: shengjiang@huawei.com
Remi Despres
RD-IPtech
3 rue du President Wilson
Levallois,
France
Email: remi.despres@free.fr
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