Attachment Individual Identifier (AII) Types for Aggregation
draft-ietf-pwe3-aii-aggregate-02

#x27;s existing IP address space can simplify the provisioning
   process.

   This document defines an AII structure based on [RFC4447] that:

     o Enables many discrete attachment individual identifiers to be
       summarized into a single AII summary value. This will enhance
       scalability by reducing the burden on AII distribution mechanisms
       and on PE memory.

     o Ensures global uniqueness if desired by the provider. This will
       facilitate Internet-wide PW connectivity and provide a means for
       providers to perform source validation on the AII distribution
       (e.g. MP-BGP) and signaling (e.g.  LDP) channels.

   This is accomplished by defining new AII types and the associated
   formats of the value field.

Metz, et al.                                                    [Page 3]
Internet Draft    draft-ietf-pwe3-aii-aggregate-02.txt     February 2007

3. Structure for the New AII Type

   [RFC4447] defines the format of the GID FEC TLV and the use and
   semantics of the attachment group identifier (AGI).

3.1. AII Type 1

   AII Type 1 has been allocated by IANA for use with provisioning
   models requiring a fixed-length 32-bit value [L2VPN-SIG]. This value
   is unique on the local PE.

3.2. AII Type 2

   The AII Type 2 structure permits varying levels of AII summarization
   to take place thus reducing the scaling burden on the aforementioned
   AII distribution mechanisms and PE memory. In other words it no
   longer becomes necessary to distribute or configure all individual
   AII values (which could number in the tens of thousands or more) on
   local PEs prior to establishing PWs to remote PEs. The details of how
   and where the aggregation of AII values is performed and then
   distributed as AII reachability information are not discussed in this
   document.

   AII Type 2 uses a combination of a provider's globally unique
   identifier (Global ID), a 32-bit prefix field and an optional 4-octet
   attachment circuit identifier field to create globally unique AII
   values.

   The encoding of AII Type 2 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  AII Type=02  |    Length     |        Global ID              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Global ID (contd.)      |        Prefix                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Prefix (contd.)         |        AC ID                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      AC ID                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                      Figure 1 AII Type 2 TLV Structure

Metz, et al.                                                    [Page 4]
Internet Draft    draft-ietf-pwe3-aii-aggregate-02.txt     February 2007

     o AII Type = 0x02

     o Length = length of value field in octets. The length is set to 8
       if the AC ID is NULL and 12 if the AC ID is non-null.

     o Global ID = This is a 4 octet field containing a value that is
       unique to the provider. The global ID can contain the 2 octet or
       4 octet value of the provider's Autonomous System Number (ASN).
       It is expected that the global ID will be derived from the
       globally unique ASN of the autonomous system hosting the PEs
       containing the actual AIIs. The presence of a global ID based on
       the provider's ASN ensures that the AII will be globally unique.

       If the PE hosting the AIIs is present in an autonomous system
       where the provider is not running BGP, chooses not to expose this
       information or does not wish to use the global ID, then the
       global ID field MUST be set to zero.  If the global ID is derived
       from a 2-octet AS number, then the high-order 4 octets of this 4
       octet field MUST be set to zero.

       Please note that the use of the provider's ASN as a global ID
       DOES NOT have anything at all to do with the use of the ASN in
       protocols such as BGP.

     o Prefix = The 32-bit prefix is a value assigned by the provider or
       it can be automatically derived from the PE's /32 IPv4 loopback
       address. Note that it is not required that the 32-bit prefix have
       any association with the IPv4 address space used in the
       provider's IGP or BGP for IP reachability.

     o Attachment Circuit (AC) ID = This is a fixed length four octet
       field used to further refine identification of an attachment
       circuit on the PE. The inclusion of the AC ID is used to identify
       individual attachment circuits that share a common prefix.  If
       the AC ID is not present then the AC ID field MUST be null and
       the AII Length field is set to 8. If the AC ID is present then
       the length field is set to 12 octets.

4. IANA Considerations

   This document requests that IANA allocate a value from the
   "Attachment Individual Identifier (AII) Type" registry defined in
   [RFC4446].

   The suggested value for this AII type is 0x02.

Metz, et al.                                                    [Page 5]
Internet Draft    draft-ietf-pwe3-aii-aggregate-02.txt     February 2007

5. Security Considerations

   AII values appear in AII distribution protocols [MP-BGP-AUTO-DISC]
   and PW signaling protocols [RFC4447] and are subject to various
   authentication schemes (i.e. MD5) if so desired.

   The use of global ID values (e.g. ASN) in the inter-provider case
   could enable a form of source-validation checking to ensure that the
   AII value (aggregated or explicit) originated from a legitimate
   source.

6. Acknowledgments

   Thanks to Carlos Pignataro, Scott Brim, Skip Booth, George Swallow
   and Bruce Davie for their input into this document.

7. Full Copyright Statement

   Copyright (C) The IETF Trust (2007).

   This document is subject to the rights, licenses and restrictions
   contained in BCP 78, and except as set forth therein, the authors
   retain all their rights.

   This document and the information contained herein are provided on an
   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
   THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
   OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
   THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

8. Intellectual Property Statement

   The IETF takes no position regarding the validity or scope of any
   Intellectual Property Rights or other rights that might be claimed to
   pertain to the implementation or use of the technology described in
   this document or the extent to which any license under such rights
   might or might not be available; nor does it represent that it has
   made any independent effort to identify any such rights.  Information
   on the procedures with respect to rights in RFC documents can be
   found in BCP 78 and BCP 79.

Metz, et al.                                                    [Page 6]
Internet Draft    draft-ietf-pwe3-aii-aggregate-02.txt     February 2007

   Copies of IPR disclosures made to the IETF Secretariat and any
   assurances of licenses to be made available, or the result of an
   attempt made to obtain a general license or permission for the use of
   such proprietary rights by implementers or users of this
   specification can be obtained from the IETF on-line IPR repository at
   http://www.ietf.org/ipr.

   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights that may cover technology that may be required to implement
   this standard.  Please address the information to the IETF at ietf-
   ipr@ietf.org.

9. Normative References

   [RFC4447], "Pseudowire Setup and Maintenance Using the Label
        Distribution Protocol (LDP)", RFC4447, April 2006

   [RFC4446], "IANA Allocations for Pseudowire Edge to Edge
        Emulation (PWE3)", RFC4446, April 2006

   [L2VPN-SIG], "Provisioning, Autodiscovery, and Signaling in
        L2VPNs", draft-ietf-l2vpn-signaling-08.txt, B. Davie, et
        al., May 2006

   [MP-BGP-AUTO-DISC], "Using BGP as an Auto-Discovery
        Mechanism for Layer-3 and Layer-2 VPNs", Ould-Brahim, H. et
        al, draft- ietf-l3vpn-bgpvpn-auto-06.txt, June 2005

10. Author Information

   Luca Martini
   Cisco Systems, Inc.
   9155 East Nichols Avenue, Suite 400
   Englewood, CO, 80112
   e-mail: lmartini@cisco.com

   Chris Metz
   Cisco Systems, Inc.
   3700 Cisco Way
   San Jose, Ca. 95134
   e-mail: chmetz@cisco.com

Metz, et al.                                                    [Page 7]
Internet Draft    draft-ietf-pwe3-aii-aggregate-02.txt     February 2007

   Florin Balus
   Nortel
   3500 Carling Ave.
   Ottawa, Ontario, CANADA
   e-mail: balus@nortel.com

   Jeff Sugimoto
   Nortel Networks
   3500 Carling Ave.
   Ottawa, Ontario, CANADA
   e-mail: sugimoto@nortel.com

Metz, et al.                                                    [Page 8]