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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


Status of this Memo

   This Internet-Draft is submitted in full conformance with the
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   This Internet-Draft will expire on April 25, 2011.

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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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