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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group Chris Metz 3 Internet Draft Luca Martini 4 Expiration Date: August 2007 Cisco Systems Inc. 6 Jeff Sugimoto Florin Balus 7 Nortel Networks Alcatel 9 February 2007 11 AII Types for Aggregation 13 draft-ietf-pwe3-aii-aggregate-02.txt 15 Status of this Memo 17 By submitting this Internet-Draft, each author represents that any 18 applicable patent or other IPR claims of which he or she is aware 19 have been or will be disclosed, and any of which he or she becomes 20 aware will be disclosed, in accordance with Section 6 of BCP 79. 22 Internet-Drafts are working documents of the Internet Engineering 23 Task Force (IETF), its areas, and its working groups. Note that other 24 groups may also distribute working documents as Internet-Drafts. 26 Internet-Drafts are draft documents valid for a maximum of six months 27 and may be updated, replaced, or obsoleted by other documents at any 28 time. It is inappropriate to use Internet-Drafts as reference 29 material or to cite them other than as "work in progress." 31 The list of current Internet-Drafts can be accessed at 32 http://www.ietf.org/1id-abstracts.html 34 The list of Internet-Draft Shadow Directories can be accessed at 35 http://www.ietf.org/shadow.html. 37 Abstract 39 The signaling protocols used to establish point-to-point pseudowires 40 include type-length-value (TLV) fields that identify pseudowire 41 endpoints called attachment individual identifiers (AII). This 42 document defines AII structures in the form of new AII type-length- 43 value fields that support AII aggregation for improved scalability 44 and VPN autodiscovery. It is envisioned that this would be useful in 45 large inter-domain virtual private wire service networks where 46 pseudowires are established between selected local and remote PE 47 nodes based on customer need. 49 Table of Contents 51 1 Specification of Requirements ........................ 2 52 2 Introduction ......................................... 2 53 3 Structure for the New AII Type ....................... 4 54 3.1 AII Type 1 ........................................... 4 55 3.2 AII Type 2 ........................................... 4 56 4 IANA Considerations .................................. 5 57 5 Security Considerations .............................. 6 58 6 Acknowledgments ...................................... 6 59 7 Full Copyright Statement ............................. 6 60 8 Intellectual Property Statement ...................... 6 61 9 Normative References ................................. 7 62 10 Author Information ................................... 7 64 1. Specification of Requirements 66 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 67 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 68 document are to be interpreted as described in RFC 2119. 70 2. Introduction 72 [RFC4447] defines the signaling mechanisms for establishing point- 73 to-point pseudowires (PWs) between two provider edge (PE) nodes. When 74 a PW is set up, the LDP signaling messages include a forwarding 75 equivalence class (FEC) element containing information about the PW 76 type and an endpoint identifier used in the selection of the PW 77 forwarder that binds the PW to the attachment circuit at each end. 79 There are two types of FEC elements defined for this purpose: PWid 80 FEC (type 128) and the Generalized ID (GID) FEC (type 129). The PWid 81 FEC element includes a fixed-length 32 bit value called the PWid that 82 serves as an endpoint identifier. The same PWid value must be 83 configured on the local and remote PE prior to PW setup. 85 The GID FEC element includes TLV fields for attachment individual 86 identifiers (AII) that, in conjunction with an attachment group 87 identifier (AGI), serve as PW endpoint identifiers. The endpoint 88 identifier on the local PE (denoted as ) is 89 called the source attachment identifier (SAI) and the endpoint 90 identifier on the remote PE (denoted as ) is 91 called the target attachment identifier (TAI). The SAI and TAI can be 92 distinct values. This is useful for applications and provisioning 93 models where the local PE (with a particular SAI) does not know and 94 must somehow learn (e.g. via MP-BGP auto-discovery) of remote TAI 95 values prior to launching PW setup messages towards the remote PE. 97 The use of the GID FEC TLV provides the flexibility to structure 98 (source or target) AII values to best fit particular application or 99 provisioning model needs [L2VPN-SIG]. For example an AII structure 100 that enables many individual AII values to be identified as a single 101 value could significantly reduce the burden on AII distribution 102 mechanisms (e.g. MP-BGP) and on PE memory needed to store this AII 103 information. It should be noted that PWE3 signaling messages will 104 always include a fully qualified AII value. 106 An AII that is globally unique would facilitate PW management and 107 security in large inter-AS and inter-provider environments. Providers 108 would not have to worry about AII value overlap during provisioning 109 or the need for AII network address translation (NAT) boxes during 110 signaling. Globally unique AII values could aid in troubleshooting 111 and could be subjected to source-validity checks during AII 112 distribution and signaling. An AII automatically derived from a 113 provider's existing IP address space can simplify the provisioning 114 process. 116 This document defines an AII structure based on [RFC4447] that: 118 o Enables many discrete attachment individual identifiers to be 119 summarized into a single AII summary value. This will enhance 120 scalability by reducing the burden on AII distribution mechanisms 121 and on PE memory. 123 o Ensures global uniqueness if desired by the provider. This will 124 facilitate Internet-wide PW connectivity and provide a means for 125 providers to perform source validation on the AII distribution 126 (e.g. MP-BGP) and signaling (e.g. LDP) channels. 128 This is accomplished by defining new AII types and the associated 129 formats of the value field. 131 3. Structure for the New AII Type 133 [RFC4447] defines the format of the GID FEC TLV and the use and 134 semantics of the attachment group identifier (AGI). 136 3.1. AII Type 1 138 AII Type 1 has been allocated by IANA for use with provisioning 139 models requiring a fixed-length 32-bit value [L2VPN-SIG]. This value 140 is unique on the local PE. 142 3.2. AII Type 2 144 The AII Type 2 structure permits varying levels of AII summarization 145 to take place thus reducing the scaling burden on the aforementioned 146 AII distribution mechanisms and PE memory. In other words it no 147 longer becomes necessary to distribute or configure all individual 148 AII values (which could number in the tens of thousands or more) on 149 local PEs prior to establishing PWs to remote PEs. The details of how 150 and where the aggregation of AII values is performed and then 151 distributed as AII reachability information are not discussed in this 152 document. 154 AII Type 2 uses a combination of a provider's globally unique 155 identifier (Global ID), a 32-bit prefix field and an optional 4-octet 156 attachment circuit identifier field to create globally unique AII 157 values. 159 The encoding of AII Type 2 is shown in figure 1. 161 0 1 2 3 162 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 1 163 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 164 | AII Type=02 | Length | Global ID | 165 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 166 | Global ID (contd.) | Prefix | 167 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 168 | Prefix (contd.) | AC ID | 169 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 170 | AC ID | 171 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 173 Figure 1 AII Type 2 TLV Structure 175 o AII Type = 0x02 177 o Length = length of value field in octets. The length is set to 8 178 if the AC ID is NULL and 12 if the AC ID is non-null. 180 o Global ID = This is a 4 octet field containing a value that is 181 unique to the provider. The global ID can contain the 2 octet or 182 4 octet value of the provider's Autonomous System Number (ASN). 183 It is expected that the global ID will be derived from the 184 globally unique ASN of the autonomous system hosting the PEs 185 containing the actual AIIs. The presence of a global ID based on 186 the provider's ASN ensures that the AII will be globally unique. 188 If the PE hosting the AIIs is present in an autonomous system 189 where the provider is not running BGP, chooses not to expose this 190 information or does not wish to use the global ID, then the 191 global ID field MUST be set to zero. If the global ID is derived 192 from a 2-octet AS number, then the high-order 4 octets of this 4 193 octet field MUST be set to zero. 195 Please note that the use of the provider's ASN as a global ID 196 DOES NOT have anything at all to do with the use of the ASN in 197 protocols such as BGP. 199 o Prefix = The 32-bit prefix is a value assigned by the provider or 200 it can be automatically derived from the PE's /32 IPv4 loopback 201 address. Note that it is not required that the 32-bit prefix have 202 any association with the IPv4 address space used in the 203 provider's IGP or BGP for IP reachability. 205 o Attachment Circuit (AC) ID = This is a fixed length four octet 206 field used to further refine identification of an attachment 207 circuit on the PE. The inclusion of the AC ID is used to identify 208 individual attachment circuits that share a common prefix. If 209 the AC ID is not present then the AC ID field MUST be null and 210 the AII Length field is set to 8. If the AC ID is present then 211 the length field is set to 12 octets. 213 4. IANA Considerations 215 This document requests that IANA allocate a value from the 216 "Attachment Individual Identifier (AII) Type" registry defined in 217 [RFC4446]. 219 The suggested value for this AII type is 0x02. 221 5. Security Considerations 223 AII values appear in AII distribution protocols [MP-BGP-AUTO-DISC] 224 and PW signaling protocols [RFC4447] and are subject to various 225 authentication schemes (i.e. MD5) if so desired. 227 The use of global ID values (e.g. ASN) in the inter-provider case 228 could enable a form of source-validation checking to ensure that the 229 AII value (aggregated or explicit) originated from a legitimate 230 source. 232 6. Acknowledgments 234 Thanks to Carlos Pignataro, Scott Brim, Skip Booth, George Swallow 235 and Bruce Davie for their input into this document. 237 7. Full Copyright Statement 239 Copyright (C) The IETF Trust (2007). 241 This document is subject to the rights, licenses and restrictions 242 contained in BCP 78, and except as set forth therein, the authors 243 retain all their rights. 245 This document and the information contained herein are provided on an 246 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 247 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND 248 THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS 249 OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF 250 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 251 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 253 8. Intellectual Property Statement 255 The IETF takes no position regarding the validity or scope of any 256 Intellectual Property Rights or other rights that might be claimed to 257 pertain to the implementation or use of the technology described in 258 this document or the extent to which any license under such rights 259 might or might not be available; nor does it represent that it has 260 made any independent effort to identify any such rights. Information 261 on the procedures with respect to rights in RFC documents can be 262 found in BCP 78 and BCP 79. 264 Copies of IPR disclosures made to the IETF Secretariat and any 265 assurances of licenses to be made available, or the result of an 266 attempt made to obtain a general license or permission for the use of 267 such proprietary rights by implementers or users of this 268 specification can be obtained from the IETF on-line IPR repository at 269 http://www.ietf.org/ipr. 271 The IETF invites any interested party to bring to its attention any 272 copyrights, patents or patent applications, or other proprietary 273 rights that may cover technology that may be required to implement 274 this standard. Please address the information to the IETF at ietf- 275 ipr@ietf.org. 277 9. Normative References 279 [RFC4447], "Pseudowire Setup and Maintenance Using the Label 280 Distribution Protocol (LDP)", RFC4447, April 2006 282 [RFC4446], "IANA Allocations for Pseudowire Edge to Edge 283 Emulation (PWE3)", RFC4446, April 2006 285 [L2VPN-SIG], "Provisioning, Autodiscovery, and Signaling in 286 L2VPNs", draft-ietf-l2vpn-signaling-08.txt, B. Davie, et 287 al., May 2006 289 [MP-BGP-AUTO-DISC], "Using BGP as an Auto-Discovery 290 Mechanism for Layer-3 and Layer-2 VPNs", Ould-Brahim, H. et 291 al, draft- ietf-l3vpn-bgpvpn-auto-06.txt, June 2005 293 10. Author Information 295 Luca Martini 296 Cisco Systems, Inc. 297 9155 East Nichols Avenue, Suite 400 298 Englewood, CO, 80112 299 e-mail: lmartini@cisco.com 301 Chris Metz 302 Cisco Systems, Inc. 303 3700 Cisco Way 304 San Jose, Ca. 95134 305 e-mail: chmetz@cisco.com 306 Florin Balus 307 Nortel 308 3500 Carling Ave. 309 Ottawa, Ontario, CANADA 310 e-mail: balus@nortel.com 312 Jeff Sugimoto 313 Nortel Networks 314 3500 Carling Ave. 315 Ottawa, Ontario, CANADA 316 e-mail: sugimoto@nortel.com