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Please use uppercase 'NOT' together with RFC 2119 keywords (if that is what you mean). Found 'MUST not' in this paragraph: When provisioning a single BFD to a bidirectional LSP, in case of the forwarding direction of session is OK but the reverse direction is not, the initiator MUST not send BFD control packets on the session until the echo reply is received from the terminator. And the terminator MUST not send BFD control packets onto the BFD session until the first BFD control packet is received from the initiator. -- The document date (December 30, 2014) is 3402 days in the past. Is this intentional? 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 informational reference (is this intentional?): RFC 4379 (Obsoleted by RFC 8029) Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group M. Chen 3 Internet-Draft Huawei 4 Intended status: Standards Track S. Ning 5 Expires: July 3, 2015 Tata Communications 6 V. Hallivuori 7 Tellabs Sinimaentie 8 December 30, 2014 10 BFD for MPLS LSPs Enhancement 11 draft-chen-mpls-bfd-enhancement-03 13 Abstract 15 This document defines extensions to BFD for MPLS LSPs that can be 16 used to specify the return path of BFD control packets for a specific 17 BFD session. Specifically, it re-uses the Reply Path TLV defined in 18 RFC7110 to specify the return path. Specifying congruent or more 19 reliable return path increases robustness of BFD failure detection 20 and reduces false positives. 22 Requirements Language 24 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 25 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 26 document are to be interpreted as described in RFC 2119 [RFC2119]. 28 Status of This Memo 30 This Internet-Draft is submitted in full conformance with the 31 provisions of BCP 78 and BCP 79. 33 Internet-Drafts are working documents of the Internet Engineering 34 Task Force (IETF). Note that other groups may also distribute 35 working documents as Internet-Drafts. The list of current Internet- 36 Drafts is at http://datatracker.ietf.org/drafts/current/. 38 Internet-Drafts are draft documents valid for a maximum of six months 39 and may be updated, replaced, or obsoleted by other documents at any 40 time. It is inappropriate to use Internet-Drafts as reference 41 material or to cite them other than as "work in progress." 43 This Internet-Draft will expire on July 3, 2015. 45 Copyright Notice 47 Copyright (c) 2014 IETF Trust and the persons identified as the 48 document authors. All rights reserved. 50 This document is subject to BCP 78 and the IETF Trust's Legal 51 Provisions Relating to IETF Documents 52 (http://trustee.ietf.org/license-info) in effect on the date of 53 publication of this document. Please review these documents 54 carefully, as they describe your rights and restrictions with respect 55 to this document. Code Components extracted from this document must 56 include Simplified BSD License text as described in Section 4.e of 57 the Trust Legal Provisions and are provided without warranty as 58 described in the Simplified BSD License. 60 Table of Contents 62 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 63 2. Session Establishment . . . . . . . . . . . . . . . . . . . . 3 64 3. Using of Tunnel sub-TLVs . . . . . . . . . . . . . . . . . . 3 65 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 66 5. Security Considerations . . . . . . . . . . . . . . . . . . . 4 67 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 68 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 4 69 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 70 8.1. Normative References . . . . . . . . . . . . . . . . . . 4 71 8.2. Informative References . . . . . . . . . . . . . . . . . 5 72 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 74 1. Introduction 76 Bi-directional Forwarding Detection (BFD) [RFC5880] for Multiprotocol 77 Label Switching (MPLS) is defined in [RFC5884], where Label Switched 78 Path (LSP) Ping [RFC4379] is used to bootstrap the BFD session. 80 In traffic engineered networks, LSPs usually do not follow IP routing 81 or there are multiple LSPs between same nodes. There is requirement 82 to specify return path for a BFD session. For example, selecting a 83 more reliable return path (e.g., TE LSP with Fast ReRoute (FRR) 84 protection) could improve the reliability of reply BFD control 85 packets or selecting co-routed LSP would ensure that failures in 86 other return paths (e.g. shortest path for IP routing) do not cause 87 BFD failure detection for the forward path. 89 This document defines extensions to BFD for MPLS LSPs that can be 90 used to specify the return path of BFD control packets for a specific 91 BFD session. 93 2. Session Establishment 95 All the procedures for session establishment defined in [RFC5884] 96 apply here. In addition to that, a RP TLV defined in [RFC7110] MUST 97 be carried in the echo request and the reply mode MUST be set to 98 "Reply via specified path". This is used to notify the egress LSR to 99 select the desired return path of the BFD session. 101 The specific return path is identified by the FEC sub-TLV encoded in 102 the RP TLV. When the return path is required to follow the reverse 103 direction of a bidirectional LSP (co-routed or associated). It just 104 needs to set the B bit of RP TLV, no specific reply path FEC sub-TLV 105 is carried. 107 When received an echo request with the reply mode set to "Reply via 108 specified path" [RFC7110], if the receiver does not know the reply 109 mode, an echo reply with the return code set to "Malformed echo 110 request" and the Subcode set to zero SHOULD be send back to the 111 initiator. The BFD session will not be established in this case. 113 When provisioning a single BFD to a bidirectional LSP, in case of the 114 forwarding direction of session is OK but the reverse direction is 115 not, the initiator MUST not send BFD control packets on the session 116 until the echo reply is received from the terminator. And the 117 terminator MUST not send BFD control packets onto the BFD session 118 until the first BFD control packet is received from the initiator. 120 3. Using of Tunnel sub-TLVs 122 IPv4/IPv6 RSVP and Static Tunnel sub-TLVs are defined in [RFC7110], 123 which are used to notify the egress LSR of a specific LSP how to 124 choose the return path for an echo reply. 126 In this document, these sub-TLVs are re-used to notify the egress LSR 127 of a specific LSP how to choose the return path of a BFD session. 129 As stated above, it is possible to have multiple parallel LSPs 130 between the ingress and egress LSRs. In a typical network, a group 131 of parallel LSPs have the same tunnel ID but different LSP IDs. 132 There is one primary and one or more secondary LSPs in each 133 direction. When establishing a BFD session for an LSP, it is common 134 for the primary LSP to choose the primary as the return path and the 135 secondary LSP to choose the secondary as the return path. With the 136 IPv4/IPv6 Tunnel sub-TLVs, operators don't have to specify a specific 137 return LSP. They just need to specify from which tunnel the return 138 LSP should be chosen, and specify the type (e.g., primary or 139 secondary) of the return LSP. The egress LSR will then choose the 140 proper return path. 142 Use of IPv4/IPv6 RSVP and Static Tunnel sub-TLVs permits Make-Before- 143 Break (MBB) on return path of BFD session. If a specific LSP other 144 than Tunnel would be selected, return path would be interrupted if 145 egress node would do MBB for the return path. This is due to the 146 fact that MBB is based on signaling new LSP with different LSP ID and 147 then deleting old LSP - after MBB selected return path would no 148 longer be available. 150 4. IANA Considerations 152 This document makes no request of IANA. 154 Note to RFC Editor: this section may be removed on publication as an 155 RFC. 157 5. Security Considerations 159 Security considerations discussed in [RFC5884], [RFC5880], [RFC5883], 160 [RFC4379] and [RFC7110] apply to this document. 162 6. Acknowledgements 164 The authors would like to thank Greg Mirsky, Xinchun Guo and Wei Cao 165 for their review and comments to this document. 167 7. Contributors 169 Vishwas Manral 171 IP Infusion 173 Almora, Uttarakhand India 175 EMail: vishwas@ipinfusion.com 177 8. References 179 8.1. Normative References 181 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 182 Requirement Levels", BCP 14, RFC 2119, March 1997. 184 [RFC5884] Aggarwal, R., Kompella, K., Nadeau, T., and G. Swallow, 185 "Bidirectional Forwarding Detection (BFD) for MPLS Label 186 Switched Paths (LSPs)", RFC 5884, June 2010. 188 [RFC7110] Chen, M., Cao, W., Ning, S., Jounay, F., and S. Delord, 189 "Return Path Specified Label Switched Path (LSP) Ping", 190 RFC 7110, January 2014. 192 8.2. Informative References 194 [RFC4379] Kompella, K. and G. Swallow, "Detecting Multi-Protocol 195 Label Switched (MPLS) Data Plane Failures", RFC 4379, 196 February 2006. 198 [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection 199 (BFD)", RFC 5880, June 2010. 201 [RFC5883] Katz, D. and D. Ward, "Bidirectional Forwarding Detection 202 (BFD) for Multihop Paths", RFC 5883, June 2010. 204 Authors' Addresses 206 Mach(Guoyi) Chen 207 Huawei 209 Email: mach.chen@huawei.com 211 So Ning 212 Tata Communications 214 Email: ning.so@tatacommunications.com 216 Ville Hallivuori 217 Tellabs Sinimaentie 219 Email: ville.hallivuori@tellabs.com