MPLS Working Group J. Ryoo Internet-Draft T. Cheung Updates: 7271 (if approved) ETRI Intended status: Standards Track H. van Helvoort Expires: April 19, 2016 Hai Gaoming BV I. Busi G. Weng Huawei Technologies October 17, 2015 Updates to MPLS Transport Profile (MPLS-TP) Linear Protection in Automatic Protection Switching (APS) Mode draft-ryoo-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. 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 April 19, 2016. Copyright Notice Copyright (c) 2015 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 Ryoo, et al. Expires April 19, 2016 [Page 1] Internet-Draft Updates to MPLS-TP LP in APS mode October 2015 (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Conventions Used in This Document . . . . . . . . . . . . . . 3 3. Updates . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.1. Initialization Behavior . . . . . . . . . . . . . . . . . 3 3.2. State Transition Modification . . . . . . . . . . . . . . 4 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 5. Security Considerations . . . . . . . . . . . . . . . . . . . 5 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 6.1. Normative References . . . . . . . . . . . . . . . . . . 5 6.2. Informative References . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction MPLS Transport Profile (MPLS-TP) linear protection in Automatic Protection Switching (APS) mode is defined in RFC 7271 [RFC7271]. The actions being performed at the initialization of the Protection State Coordination (PSC) Control Logic are not described in either [RFC7271] or RFC 6378 [RFC6378]. Although it is a common perception that the state machine starts at the Normal state (but, not explicitly specified in any of the documents), various questions have been raised concerning the detailed actions that the PSC Control Logic should take. The state machine described in [RFC7271] operates under the assumption that both end nodes of linear protection domain start in the Normal state. In the case that one node reboots while the other node is still in operation, various scenarios may arise resulting in problematic situations. This document is intended to resolve all the problematic cases and to minimize traffic disruptions related to initialization including both cold and warm reboots that require re- initialization of the PSC Control Logic. This document contains updates to the MPLS Transport Profile (MPLS- TP) linear protection in Automatic Protection Switching (APS) mode defined in [RFC7271]. The updates provide rules related to initialization of the PSC Control Logic, in which the state machine resides, when operating in APS mode. The updates also include Ryoo, et al. Expires April 19, 2016 [Page 2] Internet-Draft Updates to MPLS-TP LP in APS mode October 2015 modifications to the state transition table defined in Section 11.2 of [RFC7271]. The changes in the state transition table were 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 of today. The reader of this document is assumed to be familiar with [RFC7271]. This document shares the acronyms defined in Section 3 of [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. 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]. 3.1. Initialization Behavior When the PSC Control Logic is initialized, the following actions MUST be performed: o Stop the WTR timer if it is running. o Clear any operator command in the Local Request Logic. o If an SF-W or SF-P exists as the highest local request, transit to the PF:W:L or UA:P:L state, respectively. o When the node being initialized has no local request: * If the node being initialized does not remember the active path or if the node being initialized remembers the working path as the active path, send NR(0,0) in Normal state. * If the node being initialized remembers the protection path as the active path, send either NR(0,1) in WTR state or DNR(0,1) in DNR state depending on the configuration. Ryoo, et al. Expires April 19, 2016 [Page 3] Internet-Draft Updates to MPLS-TP LP in APS mode October 2015 o Any local SD MUST be ignored and the detection of a local SD MUST be (re-)started after the local node completes the initialization and responds to the first protocol message received from the remote node. o When the local node receives an EXER message as the first protocol message after rebooting and the remote EXER becomes the top- priority global request, align the position of the bridge and selector with the Path value in the EXER message and transit to the E::R state . Remembering the active path in case of no local request is intended to minimize traffic switchovers in case that the other node is still in operation and does not cause any problem even if the remembered active path is not valid any more due to any local input at the other node while the initializing node is out of operation. Note that while the local SD input is being ignored and there exist no other local requests, the local node restats with no local request. Since the equal priority resolution stated in Section 7.4 of [RFC7271] does not converge when the active paths that two nodes remember are different from each other. an SD detection needs to be (re-)started after both nodes converge to the same view on their active paths. It is worth noting that in some restart scenarios (e.g., cold rebooting), no valid SF/SD indications may be present at the input of the Local Request logic. In this case, the PSC Control Logic would restart as if no local requests are present. If a valid SF/SD indication is detected later on, this would be notified to the PSC Control Logic and trigger state change. 3.2. State Transition Modification State transition by remote message defined in Section 11.2 of [RFC7271] MUST be modified as follows (only modified cells are shown): | MS-W | MS-P | WTR | EXER | RR | DNR | NR --------+---------+---------+-----+------+----+------+---- N | | | (13)| | | DNR | PF:W:R | | | | | | DNR | PF:DW:R | | | | | | DNR | Ryoo, et al. Expires April 19, 2016 [Page 4] Internet-Draft Updates to MPLS-TP LP in APS mode October 2015 4. IANA Considerations This document makes no request of IANA. Note to RFC Editor: this section may be removed on publication as an RFC. 5. Security Considerations No specific security issue is raised in addition to those ones already documented in [RFC7271] 6. References 6.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC7271] Ryoo, J., Ed., Gray, E., Ed., van Helvoort, H., D'Alessandro, A., Cheung, T., and E. Osborne, "MPLS Transport Profile (MPLS-TP) Linear Protection to Match the Operational Expectations of Synchronous Digital Hierarchy, Optical Transport Network, and Ethernet Transport Network Operators", RFC 7271, DOI 10.17487/RFC7271, June 2014, . 6.2. Informative References [RFC6378] Weingarten, Y., Ed., Bryant, S., Osborne, E., Sprecher, N., and A. Fulignoli, Ed., "MPLS Transport Profile (MPLS- TP) Linear Protection", RFC 6378, DOI 10.17487/RFC6378, October 2011, . Authors' Addresses Jeong-dong Ryoo ETRI EMail: ryoo@etri.re.kr Taesik Cheung ETRI EMail: cts@etri.re.kr Ryoo, et al. Expires April 19, 2016 [Page 5] Internet-Draft Updates to MPLS-TP LP in APS mode October 2015 Huub van Helvoort Hai Gaoming BV EMail: huubatwork@gmail.com Italo Busi Huawei Technologies EMail: Italo.Busi@huawei.com Guangjuan Weng Huawei Technologies EMail: wenguangjuan@huawei.com Ryoo, et al. Expires April 19, 2016 [Page 6]