Network Working Group Chris Metz Internet Draft Luca Martini Expires: May 2006 Cisco Systems Florin Balus Jeff Sugimoto Nortel Networks October 20, 2005 AII Types for Aggregation draft-metz-aii-aggregate-01.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. This document may only be posted in an Internet-Draft. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html This Internet-Draft will expire on April 20, . Metz, et al. Expires May 2006 [Page 1]
Internet-Draft AII Types for Aggregation September 2005 Copyright Notice Copyright (C) The Internet Society (2005). All Rights Reserved. Abstract [PWE3 Control] defines the signaling mechanisms for establishing point-to-point pseudowires between two provider edge (PE) nodes. The Generalized ID FEC element contained in PWE3 signaling protocols include TLV fields that identify pseudowire endpoints called attachment individual identifiers (AII). This document defines an AII structure in the form of new AII type-length-value fields that supports AII aggregation for improved scalability. It is envisioned that this would be useful in large inter-domain virtual private wire service networks where pseudowires are established between selected local and remote PE nodes based on customer need. Conventions used in this document 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 Error! Reference source not found.. Table of Contents 1. Introduction...................................................2 2. Structure for New AII Types....................................4 2.1. PWid AII Type.............................................4 2.2. Short Prefix AII Type.....................................5 2.3. Long Prefix AII Type......................................7 3. IANA Considerations............................................9 4. Security Considerations........................................9 5. Acknowledgments...............................................10 Author's Addresses...............................................11 Intellectual Property Statement..................................12 Disclaimer of Validity...........................................12 Copyright Statement..............................................13 Acknowledgment...................................................13 1. Introduction [PWE3-CONTROL] defines the signaling mechanisms for establishing point-to-point pseudowires (PWs) between two provider edge (PE) nodes. When a PW is set up, the LDP signaling messages include a forwarding equivalence class (FEC) element containing information Metz, et al. Expires March 2006 [Page 2]
Internet-Draft AII Types for Aggregation September 2005 about the PW type and an endpoint identifier used in the selection of the PW forwarder that binds the PW to the attachment circuit at each end. There are two types of FEC elements defined for this purpose: PWid FEC (type 128) and the Generalized ID (GID) FEC (type 129). The PWid FEC element includes a fixed-length 32 bit value called the PWid that serves as an endpoint identifier. The same PWid value must be configured on the local and remote PE prior to PW setup. The GID FEC element includes TLV fields for attachment individual identifiers (AII) that, in conjunction with an attachment group identifier (AGI), serve as PW endpoint identifiers. The endpoint identifier on the local PE (denoted as <AGI, source AII or SAII) is called the source attachment identifier (SAI) and the endpoint identifier on the remote PE (denoted as <AGI, target AII or TAII) is called the target attachment identifier (TAI). The SAI and TAI can be distinct values. This is useful for applications and provisioning models where the local PE (with a particular SAI) does not know and must somehow learn (e.g. via MP-BGP auto-discovery) of remote TAI values prior to launching PW setup messages towards the remote PE. The use of the GID FEC TLV provides the flexibility to structure (source or target) AII values to best fit particular application or provisioning model needs [L2VPN-SIG]. For example an AII structure that summarizes or aggregates a large number of individual AII values could significantly reduce the burden on AII distribution mechanisms (e.g. MP-BGP) and on PE memory needed to store this AII information. An aggregate AII structure and corresponding IP next hop address could form the basis for enabling inter-domain MS-PW routing and signaling in a manner similar to the way that BGP-advertised IP address prefixes and next hops enable inter-domain IP routing. This would be useful in large inter-domain VPWS networks where PWs are established between local and remote PE based on customer need [REQ- MH-PW]. Note that this document does not discuss if, how, or where in the network the aggregation of AII values is performed, how AII aggregate reachability is distributed nor does it discuss how PW setup messages are routed through a network based on AII reachability information. An AII that is globally unique would facilitate PW management and security in large inter-AS and inter-provider environments. Providers would not have to worry about AII value overlap during provisioning or the need for AII NATs during signaling. Globally unique AII values could aid in troubleshooting and could be subjected to source- validity checks during AII distribution and signaling. Metz, et al. Expires March 2006 [Page 3]
Internet-Draft AII Types for Aggregation September 2005 An AII automatically derived from a providers existing IP address space can simplify the provisioning process. In addition an AII structure that is backwards compatible with previous endpoint identifier semantics (i.e. PWid) and other L2VPN provisioning models [L2VPN-SIG] would help providers to converge upon a PW provisioning and signaling behavior employing GID FEC TLVs. In summary the purpose of this document is to define an AII structure based on [PWE3-CONTROL] that: o Enables many discrete attachment individual identifiers to be aggregated into a single AII aggregate. 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. o Supports a uniform PW signaling mechanism employing the GID FEC TLV structure for endpoints provisioned with the AII types defined in this document, other L2VPN provisioning techniques and including those previously configured with the older FEC 128 PWid value. This is accomplished by defining three new AII types and associated formats of the value fields. 2. Structure for New AII Types [PWE3-CONTROL] defines the format of the GID FEC TLV and the use and semantics of the attachment group identifier (AGI). New AII types and the format of their associated AII value fields are defined next. 2.1. PWid AII Type The PWid AAI type provides GID FEC 129 signaling compatibility with those endpoint identifiers provisioned with the 32-bit PWid values. Unlike the FEC 128 encoding, the values of the PWid AII type do not have to match on the local and remote PE nodes. Metz, et al. Expires March 2006 [Page 4]
Internet-Draft AII Types for Aggregation September 2005 The PWid AII type can also be used when the provisioning model warrants definition of a fixed-length 32-bit value used to identify a particular attachment circuit [L2VPN-SIG]. The value of the PWid AII type can be globally unique or combined with some other value (e.g. AGI) to provide a globally unique identifier if warranted by the provisioning model. The PWid AII type is encoded as the following: 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=01 | Length | PWid | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PWid (contd.) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ o AII Type = 0x01 o Length = Length of the value field in octets. The length is set to 4 for this AII type. o PWid = Fixed-length 32-bit value. The provisioning models employing this AII type require that the entire 32-bit value field (fully-qualified) is processed by AII distribution mechanisms. This means it CANNOT be aggregated. 2.2. Short Prefix AII Type The Short Prefix AII type 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. Metz, et al. Expires March 2006 [Page 5]
Internet-Draft AII Types for Aggregation September 2005 The Short Prefix AII type uses a combination of a providers 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. It is termed the Short Prefix AII type because of the shorter 32-bit prefix used here as compared to the longer 256-bit prefix used in the Long Prefix AII type defined in the next section. The encoding of the Short Prefix AII type 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | AC ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1 Short Prefix AII TLV Structure o AII Type = 0x02 o Length = length of value field in octets. The length is set to 10 if the AC ID is NULL and 14 if the AC ID is non-null. Metz, et al. Expires March 2006 [Page 6]
Internet-Draft AII Types for Aggregation September 2005 o Global ID = This is a 6 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 providers Autonomous System Number, a global unicast IPv6 /48 prefix assigned to the provider or some other globally unique value up to 6 octets in length. It is expected that the global ID will be derived from the globally unique AS number of the autonomous system hosting the PEs containing the actual AIIs. 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 providers AS number as a global ID DOES NOT have anything at all to do with the use of the AS number 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 PEs /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 providers 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 10. If the AC ID is present then the length field is set to 14 octets. 2.3. Long Prefix AII Type The Long Prefix AII type employs a global ID and 256-bit prefix field (versus 32 bits for the Short Prefix AII type) to create AII values. The Long Prefix AII type might be useful to providers with provisioning systems or AII addressing schemes that exceed 32 bits in length. It can also be used to auto-generate AII values based on /128 IPv6 and /32 IPv4 PE loopbacks. The encoding of the Long Prefix AII type is shown in figure 2: Metz, et al. Expires March 2006 [Page 7]
Internet-Draft AII Types for Aggregation September 2005 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=03 | Length | Global ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Global ID (contd.) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | | | | | Prefix | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2 Long Prefix AII TLV Structure o AII Type = 0x03 o Length = length of value field in octets. The length is set to 38 for this AII type. o Global ID = This is a 6 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 providers Autonomous System Number, a global unicast IPv6 /48 prefix assigned to the provider or some other globally unique value up to 6 octets in length. It is expected that the global ID will be derived from the globally unique AS number of the autonomous system hosting the PEs containing the actual AIIs. 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 providers AS number as a global ID DOES NOT have anything at all to do with the use of the AS number used in protocols such as BGP. Metz, et al. Expires March 2006 [Page 8]
Internet-Draft AII Types for Aggregation September 2005 o Prefix = The 256-bit Prefix is a value assigned by the provider or it can be automatically derived from the PEs local addressing scheme such as IPv6 or IPv4. This AII type does not employ an optional AC ID field. This is because there are sufficient bits available in the prefix field to hold a fully qualified target PE value auto-generated from even a long address type such as IPv6 with the remainder available for local attachment circuit identification. 3. IANA Considerations This document requests that IANA allocate three AII types from the "Attachment Individual Identifier (AII) Type" registry defined in [IANA]. The suggested values for the AAI types are: Value Description 0x01 PWid 0x02 Short Prefix 0x03 Long Prefix 4. Security Considerations AII values appear in AII distribution protocols [MP-BGP-AUTO-DISC] and PW signaling protocols [PWE3-CONTROL] 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. Metz, et al. Expires March 2006 [Page 9]
Internet-Draft AII Types for Aggregation September 2005 5. Acknowledgments Thanks to Carlos Pignataro, Scott Brim, Skip Booth, George Swallow and Bruce Davie for their input into this document. Metz, et al. Expires March 2006 [Page 10]
Internet-Draft AII Types for Aggregation September 2005 References [PWE3-CONTROL], Pseudowire Setup and Maintenance using LDP, draft-ietf-pwe3-control-protocol-17.txt, June 2005 [IANA], "IANA Allocations for pseudo Wire Edge to Edge Emulation (PWE3)" Martini,Townsley, draft-ietf-pwe3-iana-allocation- 12.txt, work in progress), September 2005 [L2VPN-SIG], Provisioning Models and Endpoint Identifiers in L2VPN Signaling, draft-ietf-l2vpn-signaling-06.txt, Sept. 2005 [REQ-MH-PW], Requirements for inter domain Pseudo-Wires, draft- ietf-pwe3-ms-pw-requirements-00.txt, Internet Draft, June 2005 [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 Author's Addresses Chris Metz Cisco Systems, Inc. 3700 Cisco Way San Jose, Ca. 95134 Email: chmetz@cisco.com Luca Martini Cisco Systems, Inc. 9155 East Nichols Avenue, Suite 400 Englewood, CO, 80112 Email: lmartini@cisco.com Florin Balus Nortel 3500 Carling Ave. Metz, et al. Expires March 2006 [Page 11]
Internet-Draft AII Types for Aggregation September 2005 Ottawa, Ontario, CANADA Email: balus@nortel.com Jeff Sugimoto Nortel 3500 Carling Ave. Ottawa, Ontario, CANADA Email: sugimoto@nortel.com 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. 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 Disclaimer of Validity 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 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. Metz, et al. Expires March 2006 [Page 12]
Internet-Draft AII Types for Aggregation September 2005 Copyright Statement Copyright (C) The Internet Society (2005). 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. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Metz, et al. Expires March 2006 [Page 13]