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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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: draft-ietf-pce-pce-initiated-lsp has been published as RFC 8281 == Outdated reference: draft-ietf-pce-stateful-pce has been published as RFC 8231 Summary: 0 errors (**), 0 flaws (~~), 3 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 PCE Working Group S. Sivabalan 3 Internet-Draft J. Medved 4 Intended status: Standards Track Cisco Systems, Inc. 5 Expires: October 22, 2015 I. Minei 6 Google, Inc. 7 E. Crabbe 9 R. Varga 10 Pantheon Technologies SRO 11 J. Tantsura 12 Ericsson 13 J. Hardwick 14 Metaswitch Networks 15 April 20, 2015 17 Conveying path setup type in PCEP messages 18 draft-ietf-pce-lsp-setup-type-02.txt 20 Abstract 22 A Path Computation Element can compute traffic engineering paths (TE 23 paths) through a network that are subject to various constraints. 24 Currently, TE paths are label switched paths (LSPs) which are set up 25 using the RSVP-TE signaling protocol. However, other TE path setup 26 methods are possible within the PCE architecture. This document 27 proposes an extension to PCEP to allow support for different path 28 setup methods over a given PCEP session. 30 Requirements Language 32 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 33 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 34 document are to be interpreted as described in [RFC2119]. 36 Status of this Memo 38 This Internet-Draft is submitted in full conformance with the 39 provisions of BCP 78 and BCP 79. 41 Internet-Drafts are working documents of the Internet Engineering 42 Task Force (IETF). Note that other groups may also distribute 43 working documents as Internet-Drafts. The list of current Internet- 44 Drafts is at http://datatracker.ietf.org/drafts/current/. 46 Internet-Drafts are draft documents valid for a maximum of six months 47 and may be updated, replaced, or obsoleted by other documents at any 48 time. It is inappropriate to use Internet-Drafts as reference 49 material or to cite them other than as "work in progress." 51 This Internet-Draft will expire on October 22, 2015. 53 Copyright Notice 55 Copyright (c) 2015 IETF Trust and the persons identified as the 56 document authors. All rights reserved. 58 This document is subject to BCP 78 and the IETF Trust's Legal 59 Provisions Relating to IETF Documents 60 (http://trustee.ietf.org/license-info) in effect on the date of 61 publication of this document. Please review these documents 62 carefully, as they describe your rights and restrictions with respect 63 to this document. Code Components extracted from this document must 64 include Simplified BSD License text as described in Section 4.e of 65 the Trust Legal Provisions and are provided without warranty as 66 described in the Simplified BSD License. 68 Table of Contents 70 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 71 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 4 72 3. Path Setup Type TLV . . . . . . . . . . . . . . . . . . . . . . 5 73 4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 74 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 7 75 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7 76 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7 77 8. Normative References . . . . . . . . . . . . . . . . . . . . . 7 78 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 80 1. Introduction 82 [RFC5440] describes the Path Computation Element Protocol (PCEP) for 83 communication between a Path Computation Client (PCC) and a Path 84 Control Element (PCE) or between one a pair of PCEs. A PCC requests 85 a path subject to various constraints and optimization criteria from 86 a PCE. The PCE responds to the PCC with a hop-by-hop path in an 87 Explicit Route Object (ERO). The PCC uses the ERO to set up the path 88 in the network. 90 [I-D.ietf-pce-stateful-pce] specifies extensions to PCEP that allow a 91 PCC to delegate its LSPs to a PCE. The PCE can then update the state 92 of LSPs delegated to it. In particular, the PCE may modify the path 93 of an LSP by sending a new ERO. The PCC uses this ERO to re-route 94 the LSP in a make-before-break fashion. 95 [I-D.ietf-pce-pce-initiated-lsp] specifies a mechanism allowing a PCE 96 to dynamically instantiate an LSP on a PCC by sending the ERO and 97 characteristics of the LSP. The PCC signals the LSP using the ERO 98 and other attributes sent by the PCE. 100 So far, the PCEP protocol and its extensions implicitly assume that 101 the TE paths are label switched, and are established via the RSVP-TE 102 protocol. However, other methods of LSP setup are not precluded. 103 When a new path setup method (other than RSVP-TE) is introduced for 104 setting up a path, a new capability TLV pertaining to the new path 105 setup method MAY be advertised when the PCEP session is established. 106 Such capability TLV MUST be defined in the specification of the new 107 path setup type. When multiple path setup methods are deployed in a 108 network, a given PCEP session may have to simultaneously support more 109 than one path setup types. In this case, the intended path setup 110 method needs to be either explicitly indicated or implied in the 111 appropriate PCEP messages (when necessary) so that both the PCC and 112 the PCE can take the necessary steps to set up the path. This 113 document introduces a generic TLV called "PATH-SETUP-TYPE TLV" and 114 specifies the base procedures to facilitate such operational model. 116 2. Terminology 118 The following terminologies are used in this document: 120 ERO: Explicit Route Object. 122 LSR: Label Switching Router. 124 PCC: Path Computation Client. 126 PCE: Path Computation Element 128 PCEP: Path Computation Element Protocol. 130 TLV: Type, Length, and Value. 132 3. Path Setup Type TLV 134 When a PCEP session is used to set up TE paths using different 135 methods, the corresponding PCE and PCC must be aware of the path 136 setup method used. That means, a PCE must be able to specify paths 137 in the correct format and a PCC must be able take control and take 138 forwarding plane actions appropriate to the path setup type. 140 0 1 2 3 141 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 1 142 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 143 | Type | Length | 144 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 145 | Reserved | PST | 146 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 148 Figure 1: PATH-SETUP-TYPE TLV 150 PATH-SETUP-TYPE TLV is an optional TLV associated with the RP 151 ([RFC5440]) and the SRP ([I-D.ietf-pce-stateful-pce]) objects. Its 152 format is shown in the above figure. The type of the TLV is to be 153 defined by IANA. The one octet value contains the Path Setup Type 154 (PST). This document specifies the following PST value: 156 o PST = 0: Path is setup via RSVP-TE signaling protocol(default). 158 The absence of the PATH-SETUP-TYPE TLV is equivalent to an PATH- 159 SETUP-TYPE TLV with an PST value of 0. It is recommended to omit the 160 TLV in the default case. If the RP or SRP object contains more than 161 one PATH-SETUP-TYPE TLVs, only the first TLV MUST be processed and 162 the rest MUST be ignored. 164 If a PCEP speaker does not recognize the PATH-SETUP-TYPE TLV, it MUST 165 ignore the TLV in accordance with ([RFC5440]). If a PCEP speaker 166 recognizes the TLV but does not support the TLV, it MUST send PCErr 167 with Error-Type = 2 (Capability not supported). 169 4. Operation 171 When requesting a path from a PCE using a PCReq message ([RFC5440]), 172 a PCC MAY include the PATH-SETUP-TYPE TLV in the RP object. If the 173 PCE is capable of expressing the path in a format appropriate to the 174 setup method used, it MUST use the appropriate ERO format in the 175 PCRep message. If the path setup type cannot be inferred from the 176 ERO or any other object or TLV in the PCRep message, PATH-SETUP-TYPE 177 TLV may be included in the RP object of the PCRep message. 178 Regardless of whether PATH-SETUP-TYPE TLV is used or not, if the PCE 179 does not support the intended path setup type it MUST send PCErr with 180 Error-Type = TBD (Traffic engineering path setup error) (recommended 181 value is 21) and Error-Value = 1 (Unsupported path setup type) and 182 close the PCEP session. If the path setup types corresponding to the 183 PCReq and PCRep messages do not match, the PCC MUST send a PCErr with 184 Error-Type = 21 (Traffic engineering path setup error) and Error- 185 Value = 2 (Mismatched path setup type) and close the PCEP session. 187 In the case of stateful PCE, if the path setup type cannot be 188 unambiguously inferred from ERO or any other object or TLV, PATH- 189 SETUP-TYPE TLV MAY be used in PCRpt and PCUpd messages. If PATH- 190 SETUP-TYPE TLV is used in PCRpt message, the SRP object MUST be 191 present even in cases when the SRP-ID-number is the reserved value of 192 0x00000000. Regardless of whether PATH-SETUP-TYPE TLV is used or 193 not, if a PCRpt message is triggered due to a PCUpd message (in this 194 case SRP-ID-number is not equal to 0x00000000), the path setup types 195 corresponding to the PCRpt and PCUpd messages should match. 196 Otherwise, the PCE MUST send PCErr with Error-Type = 21 (Traffic 197 engineering path setup error) and Error-Value = 2 (Mismatched path 198 setup type) and close the connection. 200 In the case of PCE initiated LSPs, a PCE MAY include PATH-SETUP-TYPE 201 TLV in PCInitiate message if the message does not have any other 202 means of indicating path setup type. If a PCC does not support the 203 path setup type associated with the PCInitiate message, the PCC MUST 204 send PCErr with Error-Type = 21 (Traffic engineering path setup 205 error) and Error-Value = 1 (Unsupported path setup type) and close 206 the PCEP session. Similarly, as mentioned above, if the path setup 207 type cannot be unambiguously inferred from ERO or any other object or 208 TLV, the PATH-SETUP-TYPE TLV MAY be included in PCRpt messages 209 triggered by PCInitiate message. Regardless of whether PATH-SETUP- 210 TYPE TLV is used or not, if a PCRpt message is triggered by a 211 PCInitiate message, the path setup types corresponding to the PCRpt 212 and the PCInitiate messages should match. Otherwise, the PCE MUST 213 send PCErr message with Error-Type = 21 (Traffic engineering path 214 setup error) and Error-Value = 2 (Mismatched path setup type). 216 5. Security Considerations 218 No additional security measure is required. 220 6. IANA Considerations 222 IANA is requested to allocate a new TLV type (recommended value is 223 28)for PATH-SETUP-TYPE TLV specified in this document. 225 This document requests that a registry is created to manage the value 226 of the path Setup Type field in the PATH-SETUP-TYPE TLV. 228 Value Description Reference 230 0 Traffic engineering This document 231 path is setup using 232 RSVP signaling 233 protocol 235 This document also defines a new Error-Type (recommended 21) and new 236 Error-Values for the following new error conditions: 238 Error-Type Meaning 239 21 Invalid traffic engineering path setup type 240 Error-value=1: Unsupported path setup type 241 Error-value=2: Mismatched path setup type 243 7. Acknowledgements 245 We like to thank Marek Zavodsky for valuable comments. 247 8. Normative References 249 [I-D.ietf-pce-pce-initiated-lsp] 250 Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "PCEP 251 Extensions for PCE-initiated LSP Setup in a Stateful PCE 252 Model", draft-ietf-pce-pce-initiated-lsp-03 (work in 253 progress), March 2015. 255 [I-D.ietf-pce-stateful-pce] 256 Crabbe, E., Minei, I., Medved, J., and R. Varga, "PCEP 257 Extensions for Stateful PCE", 258 draft-ietf-pce-stateful-pce-10 (work in progress), 259 October 2014. 261 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 262 Requirement Levels", BCP 14, RFC 2119, March 1997. 264 [RFC5440] Vasseur, JP. and JL. Le Roux, "Path Computation Element 265 (PCE) Communication Protocol (PCEP)", RFC 5440, 266 March 2009. 268 Authors' Addresses 270 Siva Sivabalan 271 Cisco Systems, Inc. 272 2000 Innovation Drive 273 Kanata, Ontario K2K 3E8 274 Canada 276 Email: msiva@cisco.com 278 Jan Medved 279 Cisco Systems, Inc. 280 170 West Tasman Dr. 281 San Jose, CA 95134 282 USA 284 Email: jmedved@cisco.com 286 Ina Minei 287 Google, Inc. 288 1600 Amphitheatre Parkway 289 Mountain View, CA 94043 290 USA 292 Email: inaminei@google.com 294 Edward Crabbe 296 Robert Varga 297 Pantheon Technologies SRO 298 Mlynske Nivy 56 299 Bratislava, 821 05 300 Slovakia 302 Email: robert.vargad@pantheon.sk 303 Jeff Tantsura 304 Ericsson 305 300 Holger Way 306 San Jose, CA 95134 307 USA 309 Email: jeff.tantsura@ericsson.com 311 Jon Hardwick 312 Metaswitch Networks 313 100 Church Street 314 Enfield, Middlesex 315 UK 317 Email: jon.hardwick@metaswitch.com