--- 1/draft-ietf-mpls-tp-aps-updates-00.txt 2016-09-15 21:15:58.658618257 -0700 +++ 2/draft-ietf-mpls-tp-aps-updates-01.txt 2016-09-15 21:15:58.674618660 -0700 @@ -1,50 +1,51 @@ MPLS Working Group J. Ryoo Internet-Draft T. Cheung Updates: 7271 (if approved) ETRI Intended status: Standards Track H. van Helvoort -Expires: September 20, 2016 Hai Gaoming BV +Expires: March 19, 2017 Hai Gaoming BV I. Busi G. Weng Huawei Technologies - March 19, 2016 + September 15, 2016 Updates to MPLS Transport Profile (MPLS-TP) Linear Protection in Automatic Protection Switching (APS) Mode - draft-ietf-mpls-tp-aps-updates-00.txt + draft-ietf-mpls-tp-aps-updates-01.txt Abstract This document contains updates to MPLS Transport Profile (MPLS-TP) linear protection in Automatic Protection Switching (APS) mode defined in RFC 7271. The updates provide rules related to the initialization of the Protection State Coordination (PSC) Control Logic, in which the state machine resides, when operating in APS - mode. + mode, and clarify some operation related to state transition table + lookup. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - This Internet-Draft will expire on September 20, 2016. + This Internet-Draft will expire on March 19, 2017. Copyright Notice Copyright (c) 2016 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents @@ -55,27 +56,28 @@ described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Conventions Used in This Document . . . . . . . . . . . . . . 3 3. Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. Updates . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4.1. Initialization Behavior . . . . . . . . . . . . . . . . . 4 4.2. State Transition Modification . . . . . . . . . . . . . . 5 - 5. Security Considerations . . . . . . . . . . . . . . . . . . . 5 - 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 - 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 - 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 - 8.1. Normative References . . . . . . . . . . . . . . . . . . 6 - 8.2. Informative References . . . . . . . . . . . . . . . . . 6 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 + 4.3. Operation related to State Transition Table Lookup . . . 6 + 5. Security Considerations . . . . . . . . . . . . . . . . . . . 7 + 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 + 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7 + 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 + 8.1. Normative References . . . . . . . . . . . . . . . . . . 7 + 8.2. Informative References . . . . . . . . . . . . . . . . . 7 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 1. Introduction MPLS Transport Profile (MPLS-TP) linear protection in Automatic Protection Switching (APS) mode is defined in RFC 7271 [RFC7271]. It defines a set of alternate and additional mechanisms to perform some of the functions of linear protection described in RFC 6378 [RFC6378]. The actions performed at initialization of the Protection State Coordination (PSC) Control Logic are not described in either [RFC7271] or [RFC6378]. Although it is a common perception that the @@ -102,30 +104,32 @@ of [RFC7271]. The changes in the state transition table have been examined to make sure that they do not introduce any new problems. This document does not introduce backward compatibility issues with implementations of [RFC7271]. In case a node implementing this document restarts, the new state changes will not cause problems at the remote node implementing [RFC7271] and the two ends will converge to the same local and remote states. In case a node implementing [RFC7271] restarts, the two ends behave as today. + This document also provides some clarifications on the operation + related to state transition table lookup. + The reader of this document is assumed to be familiar with [RFC7271]. 2. Conventions Used in This Document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. 3. Acronyms - This document uses the following acronyms: APS Automatic Protection Switching DNR Do-not-Revert E::R Exercise state due to remote EXER message EXER Exercise MS-P Manual Switch to Protection path MS-W Manual Switch to Working path MPLS-TP MPLS Transport Profile N Normal state @@ -136,24 +140,25 @@ PSC Protection State Coordination RR Reverse Request SD Signal Degrade SF-P Signal Fail on Protection path SF-W Signal Fail on Working path UA:P:L Unavailable state due to local SF-P WTR Wait-to-Restore 4. Updates - This document updates [RFC7271] by specifying the actions that will - be performed at the initialization of the PSC Control Logic and - modifies the state transition table defined in Section 11.2 of - [RFC7271]. + This section specifies the actions that will be performed at the + initialization of the PSC Control Logic and the modifications of the + state transition table defined in Section 11.2 of [RFC7271]. Some + clarifications on the operation related to state transition table + lookup are also provided. 4.1. Initialization Behavior This section defines initialization behavior that is not described in [RFC7271]. When the PSC Control Logic is initialized, the following actions MUST be performed: o Stop the WTR timer if it is running. @@ -220,20 +225,51 @@ The changes in two rows of remote protecting failure states lead to the replacement of note (10) with DNR, therefore note (10) is no longer needed. The resultant three rows read: | MS-W | MS-P | WTR | EXER | RR | DNR | NR --------+---------+---------+-----+------+----+------+---- N | SA:MW:R | SA:MP:R | (13)| E::R | i | DNR | i PF:W:R | SA:MW:R | SA:MP:R | (9) | E::R | i | DNR | (11) PF:DW:R | SA:MW:R | SA:MP:R | (9) | E::R | i | DNR | (11) +4.3. Operation related to State Transition Table Lookup + + In addition to the rules related to the state transition table lookup + listed in Section 11 of [RFC7271], the following rule is also applied + to the operation related to the state transition table lookup: + + o When the local SF-P is cleared and the priorities of the local and + remote requests are re-evaluated, the last received remote message + may not be valid any more due to the previous failure of the + protection path. Therefore, the last received message MUST be + treated as if it were NR and only the local request shall be + evaluated. + + The last paragraph in Section 11 of [RFC7271] is modified as follows: + + --------- + Old text: + --------- + In the state transition tables below, the letter 'i' stands for + "ignore" and is an indication to remain in the current state and + continue transmitting the current PSC message. + --------- + New text: + --------- + In the state transition tables below, the letter 'i' stands for + "ignore" and the top-priority global request is ignored. + Therefore, the next state can be either the current state + transmitting the current PSC message or the supposed state + (Normal or DNR depending on the footnotes to the state transition + tables) in case of re-evaluation. + 5. Security Considerations No specific security issue is raised in addition to those ones already documented in [RFC7271]. It may be noted that tightening the description of initializing behavior may help to protect networks from re-start attacks. 6. IANA Considerations This document makes no request of IANA.