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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 4447 (Obsoleted by RFC 8077) Summary: 1 error (**), 0 flaws (~~), 1 warning (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 PWE3 Working Group Kamran Raza 2 Internet Draft Sami Boutros 3 Intended Status: Standards Track Carlos Pignataro 4 Expiration Date: August 5, 2012 5 Cisco Systems 7 February 6, 2012 9 LDP Typed Wildcard FEC for PWid and Generalized PWid 10 FEC Elements 12 draft-ietf-pwe3-pw-typed-wc-fec-03.txt 14 Status of this Memo 16 This Internet-Draft is submitted in full conformance with the 17 provisions of BCP 78 and BCP 79. This document may not be modified, 18 and derivative works of it may not be created, except to publish it 19 as an RFC and to translate it into languages other than English. 21 Internet-Drafts are working documents of the Internet Engineering 22 Task Force (IETF), its areas, and its working groups. Note that 23 other groups may also distribute working documents as Internet- 24 Drafts. 26 Internet-Drafts are draft documents valid for a maximum of six 27 months and may be updated, replaced, or obsoleted by other documents 28 at any 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/ietf/1id-abstracts.txt 34 The list of Internet-Draft Shadow Directories can be accessed at 35 http://www.ietf.org/shadow.html 37 This Internet-Draft will expire on August 5, 2012. 39 Copyright Notice 41 Copyright (c) 2012 IETF Trust and the persons identified as the 42 document authors. All rights reserved. 44 This document is subject to BCP 78 and the IETF Trust's Legal 45 Provisions Relating to IETF Documents 46 (http://trustee.ietf.org/license-info) in effect on the date of 47 publication of this document. Please review these documents 48 carefully, as they describe your rights and restrictions with 49 respect to this document. Code Components extracted from this 50 document must include Simplified BSD License text as described in 51 Section 4.e of the Trust Legal Provisions and are provided without 52 warranty as described in the Simplified BSD License. 54 Abstract 56 The "Typed Wildcard Forwarding Equivalence Class (FEC) Element" 57 defines an extension to the Label Distribution Protocol (LDP) that 58 can be used when it is desired to request or withdraw or release all 59 label bindings for a given FEC Element type. However, a typed 60 wildcard FEC element must be individually defined for each FEC 61 element type. This specification defines the typed wildcard FEC 62 elements for the PWid (0x80) and Generalized PWid (0x81) FEC element 63 types. 65 Conventions used in this document 67 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 68 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 69 document are to be interpreted as described in RFC-2119 [RFC2119]. 71 Table of Contents 73 1. Introduction .................................................. 3 74 2. Typed Wildcard for PW FEC Elements ............................ 3 75 3. Applicability Statement ....................................... 4 76 4. Operation ..................................................... 5 77 4.1. PW Consistency Check ...................................... 5 78 4.2. PW Graceful Shutdown ...................................... 5 79 4.3. Wildcard PW Status ........................................ 6 80 4.4. Typed Wildcard MAC Withdrawal in VPLS ..................... 6 81 5. Security Considerations ....................................... 7 82 6. IANA Considerations ........................................... 7 83 7. Acknowledgments ............................................... 7 84 8. References .................................................... 7 85 8.1. Normative References ...................................... 7 86 8.2. Informative References .................................... 8 87 Authors' Addresses ............................................... 8 89 1. Introduction 91 An extension [RFC5918] to the Label Distribution Protocol (LDP) 92 [RFC5036] defines the general notion of a "Typed Wildcard Forwarding 93 Equivalence Class (FEC) Element". This can be used when it is 94 desired to request all label bindings for a given type of FEC 95 Element, or to release or withdraw all label bindings for a given 96 type of FEC element. However, a typed wildcard FEC element must be 97 individually defined for each type of FEC element. 99 [RFC4447] defines the "PWid FEC Element" and "Generalized PWid FEC 100 Element", but does not specify the Typed Wildcard format for these 101 elements. This document specifies the format of the Typed Wildcard 102 FEC Element for the "PWid FEC Element" and "Generalized PWid FEC 103 Element". The procedures for Typed Wildcard processing for PWid and 104 Generalized PWid FEC Elements are same as described in [RFC5918] for 105 any typed wildcard FEC Element type. 107 2. Typed Wildcard for PW FEC Elements 109 The format of the Typed Wildcard FEC Element for PWid and 110 Generalized PWid is specified as: 112 0 1 2 3 113 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 1 114 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 115 |Typed Wcard=0x5| Type=PW FEC | Len = 2 |R| PW type | 116 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 117 | . . . | 118 +-+-+-+-+-+-+-+-+ 120 Figure 1: Format of Typed Wildcard FEC Element for PW FEC Element 121 Types 123 Where: 125 Typed Wcard (one octet): Typed Wildcard FEC element type (0x05) 126 as specified in [RFC5918] 128 [FEC Element] Type (one octet): PW FEC Element type: 130 PWid: (type 0x80 [RFC4447]) 131 Generalized PWid: (type 0x81 [RFC4447]) 133 Len [FEC Type Info] (one octet): Two. (i.e. there is additional 134 FEC info to scope the Typed Wildcard) 136 R bit (Reserved bit): Must be set to ZERO on transmit and ignored 137 on receipt. 139 PW type (15-bits): PW type as specified in [RFC4447]. This field 140 is used to scope the wildcard FEC operation to limit to all 141 PWs of a given type. This MUST be set to "Wildcard" type 142 (0x7FFF), as defined in [IANA-PWE3], when referring PWs of 143 all types (see Section 4 for its usage). 145 [RFC4447] defines "PW Grouping ID TLV" that can be used for wildcard 146 withdrawal or status messages related to Generalized PWid FECs. When 147 Typed Wildcard FEC for Generalized PWid FEC element is in use, "PW 148 Grouping ID TLV" MUST NOT be present in the same message. If found 149 present, the receiving LSR MUST ignore this TLV silently, and process 150 the rest of the message. 152 3. Applicability Statement 154 The Typed wildcard FEC Elements defined in this document for the 155 PWid and Generalized PWid FEC Elements provide a finer degree of 156 granularity when compared to the wildcard FEC mechanics defined in 157 [RFC5036]. 159 The PWid FEC Element as defined in [RFC4447] contains a Group ID 160 field. This field is defined as an arbitrary 32-bit value that 161 represents a group of PWs, and is used to create groups in the PW 162 space, including potentially a single group of all PWs for a given 163 FEC Element type. This grouping enables an LSR to send "wildcard" 164 label withdrawals and/or status notification messages corresponding 165 to a PW group upon physical port failures. Similarly, [RFC4447] 166 defines the "PW Grouping ID TLV" used in the same fashion for the 167 Generalized PWid FEC Element. 169 The PW Typed Wildcard FEC elements defined in this document help us 170 achieve the similar functionality as "Group ID" field or "PW Grouping 171 ID TLV" for label withdrawal and status notification messages; 172 Additionally, the Typed Wildcard procedures [RFC5918] also provide 173 more generalized and comprehensive solution by allowing: 175 1. Typed-Wildcard Label Request messages 176 2. Label TLV in label messages to further constraint the wildcard to 177 all FECs of the specified FEC type [and its specific filter] that 178 are also bound to the specified label. 180 This document allows the use of Typed Wildcard PW FEC Element in any 181 LDP message that specifies a FEC TLV as mandatory or optional 182 parameter of the message. In addition to LDP label messages, this 183 also applies to Notification messages (containing PW Status) and 184 Address Withdraw (for MAC address withdrawal [RFC4762]) in the 185 context of LDP PW signaling. When a Typed Wildcard PW FEC element is 186 used in a Address Withdraw message for VPLS MAC address withdrawal, 187 the MAC List TLV MUST contain an empty list. 189 4. Operation 191 The use of Typed Wildcard FEC elements for PW can be useful under 192 several scenarios. This section describes some use cases to 193 illustrate their usage. The following use cases consider two LSR 194 nodes, A and B, with LDP session between them to exchange L2VPN PW 195 bindings. 197 4.1. PW Consistency Check 199 A user may request a control plane consistency check at LSR A for 200 the Generalized PWid FEC bindings that it had learnt from LSR B over 201 LDP session. To perform this consistency check, LSR A marks all its 202 learnt Generalized PWid FEC bindings from LSR B as stale, and then 203 sends a Label Request message towards LSR B for Typed Wildcard FEC 204 element for Generalized PWid FEC element type with PW type set to 205 "Wildcard" (0x7FFF). Upon receipt of such request, LSR B replays its 206 database related to Generalized PWid FEC element using one or more 207 Label Mapping messages. As a PW binding is received at LSR A, the 208 associated binding state is marked as refreshed (no stale). When 209 replay completes for Generalized PWid FEC type, LSR B marks end of 210 its replay by sending End-of-LIB notification [RFC5919] 211 corresponding to Generalized PWid FEC element type. Upon receipt of 212 this notification at LSR A, any remaining stale PW binding of 213 Generalized PWid FEC type learnt from the peer LSR B, is cleaned up 214 and removed from the database. This completes consistency check with 215 LSR B at LSR A for Generalized PWid FEC type. 217 4.2. PW Graceful Shutdown 219 It may be desirable to perform shutdown/removal of existing PW 220 bindings advertised towards a peer in a graceful manner - i.e. all 221 advertised PW bindings to be removed from a peer without session 222 flap. For example, to request a graceful delete of the PWid FEC and 223 Generalized PWid FEC bindings at LSR A learnt from LSR B, LSR A 224 would send a Label Withdraw message towards LSR B with Typed 225 Wildcard FEC elements pertaining to PWid FEC element (with PW type 226 set to 0x7FFF) and Generalized PWid FEC element (with PW type set to 227 0x7FFF). Upon receipt of such message, LSR B will delete all PWid 228 and Generalized PWid bindings learnt from LSR A. Afterwards, LSR B 229 would send Label Release messages corresponding to received Label 230 Withdraw messages with Typed FEC element. 232 4.3. Wildcard PW Status 234 The Typed Wildcard FEC Elements for PW FECs can be very useful when 235 used to convey PW status amongst LSRs. The PE devices can send "PW 236 Status TLV" in an LDP Notification message to indicate PW status 237 (i.e., a Pseudowire Status Code denoting for example a particular 238 fault) to their remote peers [RFC4447]. In case of a global failure 239 affecting all PWs, an LSR typically sends one PW Status LDP 240 Notification message per PW. This per PW Status message has 241 scalability implications in a large-scale network with large number 242 of PWs. 244 Using Typed Wildcard FEC Element for given type of PW FEC Element, 245 the LSR will need to send only one PW Status Notification message 246 with Typed Wildcard PW FEC specified to notify about the common 247 status applicable to all PWs as scoped by the PW Typed Wildcard FEC. 249 4.4. Typed Wildcard MAC Withdrawal in VPLS 251 [RFC4762] defines a pseudowire based solution to implement Virtual 252 Private LAN Service (VPLS). Section 6.2 of RFC-4762 describes MAC 253 Withdrawal procedures and extensions in an VPLS environment. These 254 procedures use LDP Address Withdraw message containing FEC TLV (with 255 PW FEC element corresponding to the VPLS instance) and MAC List TLV 256 (to specify addresses to be withdrawn). RFC-4762 procedures also 257 allow MAC addresses withdrawal wildcarding for a given VPLS instance. 259 Using RFC-4762 procedures, a PE LSR can withdraw all MAC addresses 260 for a given VPLS instance by sending an Address Withdraw message with 261 VPLS instance corresponding PW FEC element in a FEC TLV, and MAC List 262 TLV with an empty list of addresses. If there are more than one VPLS 263 instance on a given PE LSR node, separate Address Withdraw messages 264 will need to be sent by PE LSR if it wishes to withdraw MAC addresses 265 for all or subset of VPLS instances upon some global failure or 266 configuration. This per PW (VPLS instance) MAC Withdraw messages may 267 have some scalability implications in large-scale network. 269 As stated in section 3, this document allows use of Typed Wildcard PW 270 FEC in Address Withdraw messages corresponding to VPLS MAC 271 Withdrawal. The usage of PW Typed Wildcard FEC enhances the scope of 272 MAC withdrawal beyond just a single VPLS instance, and allows a PE 273 node to wildcard withdraw all MAC addresses for: 275 o all VPLS instances; or 276 o all VPLS instances corresponding to a given PW type. 278 5. Security Considerations 280 No new security considerations beyond that apply to the base LDP 281 specification [RFC5036], [RFC4447], [RFC4762], and [RFC5920] apply to 282 the use of the PW Typed Wildcard FEC Element types described in this 283 document. 285 6. IANA Considerations 287 None. 289 7. Acknowledgments 291 The authors would like to thank Eric Rosen, Reshad Rahman, Siva 292 Sivabalan, and Zafar Ali for their review and valuable comments. We 293 also acknowledge Daniel Cohn for suggesting the use of Typed Wildcard 294 PW FEC for VPLS MAC withdrawal. 296 This document was prepared using 2-Word-v2.0 template.dot. 298 8. References 300 8.1. Normative References 302 [RFC5036] L. Andersson, I. Minei, and B. Thomas, "LDP Specification", 303 RFC 5036, September 2007. 305 [RFC5918] R. Asati, I. Minei, and B. Thomas, "LDP Typed Wildcard 306 Forwarding Equivalence Class", RFC 5918, August 2010. 308 [RFC5919] R. Asati, P. Mohapatra, E. Chen, and B. Thomas, "Signaling 309 LDP Label Advertisement Completion", RFC 5919, August 2009. 311 [RFC4447] L. Martini, E. Rosen, El-Aawar, T. Smith, and G. Heron, 312 "Pseudowire Setup and Maintenance using the Label 313 Distribution Protocol", RFC 4447, April 2006. 315 [RFC4762] M. Lasserre, and V. Kompella, "Virtual Private LAN Service 316 (VPLS) Using Label Distribution Protocol (LDP) Signaling", 317 RFC 4762, January 2007. 319 [RFC2119] S. Bradner, "Key words for use in RFCs to Indicate 320 Requirement Levels", BCP 14, RFC2119, March 1997. 322 8.2. Informative References 324 [RFC5920] L. Fang (Editor), et al., "Security Framework for MPLS and 325 GMPLS Networks", RFC 5920, July 2010. 327 [IANA-PWE3] Internet Assigned Numbers Authority, "Pseudo Wires Name 328 Spaces (PWE3)", http://www.iana.org/assignments/pwe3- 329 parameters, May 2011. 331 Authors' Addresses 333 Kamran Raza 334 Cisco Systems, Inc., 335 2000 Innovation Drive, 336 Ottawa, ON K2K-3E8, Canada. 337 Email: skraza@cisco.com 339 Sami Boutros 340 Cisco Systems, Inc., 341 3750 Cisco Way, 342 San Jose, CA 95134, USA. 343 Email: sboutros@cisco.com 344 Carlos Pignataro 345 Cisco Systems, Inc., 346 7200 Kit Creek Road, 347 Research Triangle Park, NC 27709-4987, USA. 348 Email: cpignata@cisco.com