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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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-11) exists of draft-ietf-pce-pce-initiated-lsp-01 == Outdated reference: A later version (-21) exists of draft-ietf-pce-stateful-pce-09 Summary: 0 errors (**), 0 flaws (~~), 3 warnings (==), 1 comment (--).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: January 1, 2015 I. Minei 6 E. Crabbe 7 Google, Inc. 8 R. Varga 9 Pantheon Technologies SRO 10 June 30, 2014 12 Conveying path setup type in PCEP messages 13 draft-sivabalan-pce-lsp-setup-type-02.txt 15 Abstract 17 A Path Computation Element can compute traffic engineering paths (TE 18 paths) through a network that are subject to various constraints. 19 Currently, TE paths are label switched paths (LSPs) which are set up 20 using the RSVP-TE signaling protocol. However, other TE path setup 21 methods are possible within the PCE architecture. This document 22 proposes an extension to PCEP to allow support for different path 23 setup methods over a given PCEP session. 25 Requirements Language 27 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 28 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 29 document are to be interpreted as described in [RFC2119]. 31 Status of This Memo 33 This Internet-Draft is submitted in full conformance with the 34 provisions of BCP 78 and BCP 79. 36 Internet-Drafts are working documents of the Internet Engineering 37 Task Force (IETF). Note that other groups may also distribute 38 working documents as Internet-Drafts. The list of current Internet- 39 Drafts is at http://datatracker.ietf.org/drafts/current/. 41 Internet-Drafts are draft documents valid for a maximum of six months 42 and may be updated, replaced, or obsoleted by other documents at any 43 time. It is inappropriate to use Internet-Drafts as reference 44 material or to cite them other than as "work in progress." 46 This Internet-Draft will expire on January 1, 2015. 48 Copyright Notice 50 Copyright (c) 2014 IETF Trust and the persons identified as the 51 document authors. All rights reserved. 53 This document is subject to BCP 78 and the IETF Trust's Legal 54 Provisions Relating to IETF Documents 55 (http://trustee.ietf.org/license-info) in effect on the date of 56 publication of this document. Please review these documents 57 carefully, as they describe your rights and restrictions with respect 58 to this document. Code Components extracted from this document must 59 include Simplified BSD License text as described in Section 4.e of 60 the Trust Legal Provisions and are provided without warranty as 61 described in the Simplified BSD License. 63 Table of Contents 65 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 66 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 67 3. Path Setup Type TLV . . . . . . . . . . . . . . . . . . . . . 3 68 4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 4 69 5. Security Considerations . . . . . . . . . . . . . . . . . . . 5 70 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 71 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 72 8. Normative References . . . . . . . . . . . . . . . . . . . . 6 73 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 75 1. Introduction 77 [RFC5440] describes the Path Computation Element Protocol (PCEP) for 78 communication between a Path Computation Client (PCC) and a Path 79 Control Element (PCE) or between one a pair of PCEs. A PCC requests 80 a path subject to various constraints and optimization criteria from 81 a PCE. The PCE responds to the PCC with a hop-by-hop path in an 82 Explicit Route Object (ERO). The PCC uses the ERO to set up the path 83 in the network. 85 [I-D.ietf-pce-stateful-pce] specifies extensions to PCEP that allow a 86 PCC to delegate its LSPs to a PCE. The PCE can then update the state 87 of LSPs delegated to it. In particular, the PCE may modify the path 88 of an LSP by sending a new ERO. The PCC uses this ERO to re-route 89 the LSP in a make-before-break fashion. 90 [I-D.ietf-pce-pce-initiated-lsp] specifies a mechanism allowing a PCE 91 to dynamically instantiate an LSP on a PCC by sending the ERO and 92 characteristics of the LSP. The PCC signals the LSP using the ERO 93 and other attributes sent by the PCE. 95 So far, the PCEP protocol and its extensions implicitly assume that 96 the TE paths are label switched, and are established via the RSVP-TE 97 protocol. However, other methods of LSP setup are not precluded. 98 When a new path setup method (other than RSVP-TE) is introduced for 99 setting up a path, a new capability TLV pertaining to the new path 100 setup method MAY be advertised when the PCEP session is established. 101 Such capability TLV MUST be defined in the specification of the new 102 path setup type. When multiple path setup methods are deployed in a 103 network, a given PCEP session may have to simultaneously support more 104 than one path setup types. In this case, the intended path setup 105 method needs to be either explicitly indicated or implied in the 106 appropriate PCEP messages (when necessary) so that both the PCC and 107 the PCE can take the necessary steps to set up the path. This 108 document introduces a generic TLV called "PATH-SETUP-TYPE TLV" and 109 specifies the base procedures to facilitate such operational model. 111 2. Terminology 113 The following terminologies are used in this document: 115 ERO: Explicit Route Object. 116 LSR: Label Switching Router. 117 PCC: Path Computation Client. 118 PCE: Path Computation Element 119 PCEP: Path Computation Element Protocol. 120 TLV: Type, Length, and Value. 122 3. Path Setup Type TLV 124 When a PCEP session is used to set up TE paths using different 125 methods, the corresponding PCE and PCC must be aware of the path 126 setup method used. That means, a PCE must be able to specify paths 127 in the correct format and a PCC must be able take control and take 128 forwarding plane actions appropriate to the path setup type. 130 0 1 2 3 131 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 1 132 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 133 | Type | Length | 134 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 135 | Reserved | PST | 136 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 138 Figure 1: PATH-SETUP-TYPE TLV 140 PATH-SETUP-TYPE TLV is an optional TLV associated with the RP 141 ([RFC5440]) and the SRP ([I-D.ietf-pce-stateful-pce]) objects. Its 142 format is shown in the above figure. The type of the TLV is to be 143 defined by IANA. The one octet value contains the Path Setup Type 144 (PST). This document specifies the following PST value: 146 o PST = 0: Path is setup via RSVP-TE signaling protocol(default). 148 The absence of the PATH-SETUP-TYPE TLV is equivalent to an PATH- 149 SETUP-TYPE TLV with an PST value of 0. It is recommended to omit the 150 TLV in the default case. If the RP or SRP object contains more than 151 one PATH-SETUP-TYPE TLVs, only the first TLV MUST be processed and 152 the rest MUST be ignored. 154 If a PCEP speaker does not recognize the PATH-SETUP-TYPE TLV, it MUST 155 ignore the TLV in accordance with ([RFC5440]). If a PCEP speaker 156 recognizes the TLV but does not support the TLV, it MUST send PCErr 157 with Error-Type = 2 (Capability not supported). 159 4. Operation 161 When requesting a path from a PCE using a PCReq message ([RFC5440]), 162 a PCC MAY include the PATH-SETUP-TYPE TLV in the RP object. If the 163 PCE is capable of expressing the path in a format appropriate to the 164 setup method used, it MUST use the appropriate ERO format in the 165 PCRep message. If the path setup type cannot be inferred from the 166 ERO or any other object or TLV in the PCRep message, PATH-SETUP-TYPE 167 TLV may be included in the RP object of the PCRep message. 168 Regardless of whether PATH-SETUP-TYPE TLV is used or not, if the PCE 169 does not support the intended path setup type it MUST send PCErr with 170 Error-Type = TBD (Traffic engineering path setup error) (recommended 171 value is 21) and Error-Value = 1 (Unsupported path setup type) and 172 close the PCEP session. If the path setup types corresponding to the 173 PCReq and PCRep messages do not match, the PCC MUST send a PCErr with 174 Error-Type = 21 (Traffic engineering path setup error) and Error- 175 Value = 2 (Mismatched path setup type) and close the PCEP session. 177 In the case of stateful PCE, if the path setup type cannot be 178 unambiguously inferred from ERO or any other object or TLV, PATH- 179 SETUP-TYPE TLV MAY be used in PCRpt and PCUpd messages. If PATH- 180 SETUP-TYPE TLV is used in PCRpt message, the SRP object MUST be 181 present even in cases when the SRP-ID-number is the reserved value of 182 0x00000000. Regardless of whether PATH-SETUP-TYPE TLV is used or 183 not, if a PCRpt message is triggered due to a PCUpd message (in this 184 case SRP-ID-number is not equal to 0x00000000), the path setup types 185 corresponding to the PCRpt and PCUpd messages should match. 186 Otherwise, the PCE MUST send PCErr with Error-Type = 21 (Traffic 187 engineering path setup error) and Error-Value = 2 (Mismatched path 188 setup type) and close the connection. 190 In the case of PCE initiated LSPs, a PCE MAY include PATH-SETUP-TYPE 191 TLV in PCInitiate message if the message does not have any other 192 means of indicating path setup type. If a PCC does not support the 193 path setup type associated with the PCInitiate message, the PCC MUST 194 send PCErr with Error-Type = 21 (Traffic engineering path setup 195 error) and Error-Value = 1 (Unsupported path setup type) and close 196 the PCEP session. Similarly, as mentioned above, if the path setup 197 type cannot be unambiguously inferred from ERO or any other object or 198 TLV, the PATH-SETUP-TYPE TLV MAY be included in PCRpt messages 199 triggered by PCInitiate message. Regardless of whether PATH-SETUP- 200 TYPE TLV is used or not, if a PCRpt message is triggered by a 201 PCInitiate message, the path setup types corresponding to the PCRpt 202 and the PCInitiate messages should match. Otherwise, the PCE MUST 203 send PCErr message with Error-Type = 21 (Traffic engineering path 204 setup error) and Error-Value = 2 (Mismatched path setup type). 206 5. Security Considerations 208 No additional security measure is required. 210 6. IANA Considerations 212 IANA is requested to allocate a new TLV type (recommended value is 213 TBD)for PATH-SETUP-TYPE TLV specified in this document. 215 This document requests that a registry is created to manage the value 216 of the path Setup Type field in the PATH-SETUP-TYPE TLV. 218 Value Description Reference 220 0 Traffic engineering This document 221 path is setup using 222 RSVP signaling 223 protocol 225 This document also defines a new Error-Type (recommended 21) and new 226 Error-Values for the following new error conditions: 228 Error-Type Meaning 229 21 Invalid traffic engineering path setup type 231 Error-value=1: Unsupported path setup type 232 Error-value=2: Mismatched path setup type 234 7. Acknowledgements 236 We like to thank Marek Zavodsky for valuable comments. 238 8. Normative References 240 [I-D.ietf-pce-pce-initiated-lsp] 241 Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "PCEP 242 Extensions for PCE-initiated LSP Setup in a Stateful PCE 243 Model", draft-ietf-pce-pce-initiated-lsp-01 (work in 244 progress), June 2014. 246 [I-D.ietf-pce-stateful-pce] 247 Crabbe, E., Minei, I., Medved, J., and R. Varga, "PCEP 248 Extensions for Stateful PCE", draft-ietf-pce-stateful- 249 pce-09 (work in progress), June 2014. 251 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 252 Requirement Levels", BCP 14, RFC 2119, March 1997. 254 [RFC5440] Vasseur, JP. and JL. Le Roux, "Path Computation Element 255 (PCE) Communication Protocol (PCEP)", RFC 5440, March 256 2009. 258 Authors' Addresses 260 Siva Sivabalan 261 Cisco Systems, Inc. 262 2000 Innovation Drive 263 Kanata, Ontario K2K 3E8 264 Canada 266 Email: msiva@cisco.com 268 Jan Medved 269 Cisco Systems, Inc. 270 170 West Tasman Dr. 271 San Jose, CA 95134 272 USA 274 Email: jmedved@cisco.com 275 Ina Minei 276 Google, Inc. 277 1600 Amphitheatre Parkway 278 Mountain View, CA 94043 279 USA 281 Email: inaminei@google.com 283 Edward Crabbe 284 Google, Inc. 285 1600 Amphitheatre Parkway 286 Mountain View, CA 94043 287 USA 289 Email: edc@google.com 291 Robert Varga 292 Pantheon Technologies SRO 293 Mlynske Nivy 56 294 Bratislava, 821 05 295 Slovakia 297 Email: robert.vargad@pantheon.sk