MPLS Working Group Y.Koike, Ed. Internet Draft T.Hamano M.Namiki NTT Intended status: Informational Expires: May 8, 2013 November 9, 2012 A framework for Point-to-Multipoint MPLS-TP OAM draft-hmk-mpls-tp-p2mp-oam-framework-01.txt Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. 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." 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Abstract The MPLS transport profile (MPLS-TP) is being standardized to enable carrier-grade packet transport. This document discusses and specifies P2MP framework primarily related to OAM, management, and recovery. This document is mainly based on RFC5654 and RFC6371. The main focus is on the details not covered in relevant RFCs such as RFC5654, RFC5860, RFC5921, RFC5951, RFC6371 and the draft-fbb-mpls-tp-p2mp-framework. Other requirements for p2mp transport paths, such as recovery, will also be specified in a future version on the premise that there are return paths. Note: This I-D was made and updated based on discussions in ITU-T SG15, which were described in Liaison Statements: Request advance work on the P2MP framework in the MPLS-TP (https://datatracker.ietf.org/liaison/1163/) and Progressing work on P2MP MPLS-TP connections (https://datatracker.ietf.org/liaison/1202/) This document is a product of a joint Internet Engineering Task Force (IETF) / International Telecommunications Union Telecommunications Standardization Sector (ITU-T) effort to include an MPLS Transport Profile within the IETF MPLS and PWE3 architectures to support the capabilities and functionalities of a packet transport network. Table of Contents 1. Introduction ................................................ 3 2. Conventions used in this document............................ 4 2.1. Terminology ............................................ 4 2.2. Definitions ............................................ 5 3. P2MP OAM .................................................... 5 Koike, et al. Expires May 8, 2013 [Page 2] Internet-Draft MPLS-TP p2mp OAM framework November 2012 3.1. OAM functions for proactive monitoring .................. 6 3.1.1. Continuity Check and Connectivity Verification ...... 8 3.1.2. Remote Defect Indication ........................... 9 3.1.3. Alarm Reporting .................................... 9 3.1.4. Lock Reporting ..................................... 9 3.1.5. Packet Loss Measurement ............................ 9 3.1.6. Packet Delay Measurement ........................... 9 3.1.7. Client Failure Indication .......................... 9 3.2. OAM functions for on-demand monitoring .................. 9 3.2.1. Connectivity verification .......................... 9 3.2.2. Packet loss measurement ........................... 10 3.2.3. Diagnostic tests .................................. 10 3.2.4. Route Tracing ..................................... 10 3.2.5. Packet delay measurement .......................... 10 3.3. OAM functions for administration control ............... 11 3.3.1. Lock Instruct ..................................... 11 4. Security Considerations ..................................... 11 5. IANA Considerations ........................................ 11 6. References ................................................. 11 6.1. Normative References ................................... 11 6.2. Informative References ................................. 11 7. Acknowledgments ............................................ 11 1. Introduction The demand for P2MP traffic is expected to increase due to the increase in new services such as IP-TV and video distribution services. In light of the global trend of improving energy efficiency, a point-to-multipoint (P2MP) transport function in MPLS-TP could be one of the solutions for achieving this goal from the perspective of efficient use of network resources. RFC5654[1] defines the following requirements that are specific to P2MP. Koike, et al. Expires May 8, 2013 [Page 3] Internet-Draft MPLS-TP p2mp OAM framework November 2012 - Traffic-engineered point-to-multipoint (P2MP) transport paths.(item 6). - Unidirectional point-to-multipoint(P2MP) transport paths (item 8) - Being capable of using P2MP server (sub)layer capabilities when supporting P2MP MPLS-TP transport paths(item 40) - The MPLS-TP control plane MUST support establishing all the connectivity patterns defined for the MPLS-TP data plane (i.e. unidirectional P2MP) including the configuration of protection functions and any associated maintenance functions.(item 50) Unidirectional 1+1 protection for P2MP connectivity (item 65 C) - Unidirectional 1:n protection for P2MP connectivity(item 67 B) - MPLS-TP recovery in a ring MUST protect unidirectional P2MP transport paths.(item 95) RFC5860 [2] defines MPLS-TP OAM requirements including those for unidirectional P2MP transport paths. With a unidirectional P2MP transport path, two cases are assumed as per Section 3.3 of RFC6371[3]. One is when no return path exists or not used and the other is when an out-of-band return path exists and used. In I-D[4], only a summary of various items specific to MPLS-TP P2MP framework. For example, according to the editor's note, this section will contain a summary of P2MP OAM, as described in RFC6371 [3], which defines the overall OAM architecture for MPLS-TP. Therefore, this draft intends to specify details of a P2MP framework that complements P2MP requirements and the framework of existing RFCs, particularly in terms of OAM, management, and recovery. Note: MPLS-TP functions that are applicable specifically to P2MP transport paths are outside the scope of RFC5921. 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 [1]. 2.1. Terminology EMS Element management system LSP Label Switched Path Koike, et al. Expires May 8, 2013 [Page 4] Internet-Draft MPLS-TP p2mp OAM framework November 2012 NE Network Element NMS Network Management System 2.2. Definitions None 3. P2MP OAM, management and recovery The support of P2MP OAM on the data path should be independent of the availability of a return path or the mechanism that supports the return path. Basically, only unidirectional P2MP is supported in MPLS-TP. This means that an In-band return path is out of the scope of MPLS-TP requirements. In this section, two cases, with out-band return path and without return path, are considered basics and requirements when return paths exist should be independently specified from when no return path exists. P2MP considerations are described in Section 3.7 of RFC6371. The RFC has already described some requirements with out-band return path(s). On the other hand, even if there is no return path, most of OAM requirements in RFC5860 could be met by supporting management interface through which EMS/NMS can retrieve the received OAM packets. The return path may be considered to be directed to the entity that originally requested the measurements because this may not be the head end of the P2MP connection. Therefore, the following return path should be distinctly differentiated. RP-N: A return path to the EMS/NMS through the management interface (RP-N) (This case is referred to as that in which no return path exists) RP-HE: A return path to a head end of a P2MP path using any kind of out-of-band path (This case is referred to as that in which an out-of-band return path exists) These two kinds of return paths may be applied at the same time, depending on the situations. Note: In the following sections, additional requirements are basically described function-by-function, which have not been covered Koike, et al. Expires May 8, 2013 [Page 5] Internet-Draft MPLS-TP p2mp OAM framework November 2012 or clarified in RFC5860[2] and RFC6371 [3], which have focused particularly on when return paths do not exist. 3.1. General aspects of P2MP OAM P2MP transport paths are unidirectional; therefore, there is generally no in-band return path as in the MPLS-TP transport path per se. However, there are basically two approaches for handling OAM requirements in P2MP MPLS-TP. The first one is used to report the results of the monitoring/measurement of OAM packets from the OAM target node to the EMS/NMS when the NMS usually instantiates OAM functions and requires the results of OAM monitoring functions. This approach is called RP-N. The second approach is the return path to a root (source MEP) of a P2MP path using different methods such as a unidirectional p2p transport paths, and other technology-layers, such as IP, Ethernet, and OTN, when an NE within which a root MEP resides instantiates OAM functions or receive results of OAM monitoring functions. This approach is called as RP-HE. The following requirements are supported in terms of network elements when considering RP-N. 1. OAM functions of a MEG of a P2MP transport path should be configurable using the EMS/NMS. 2. Source nodes at which the source MEP reside and OAM packets are generated should receive OAM related information such as enabling/disabling OAM functions and setting/changing OAM attributes from the EMS/NMS on a P2MP transport path. 3. Sink nodes at which targeting MIPs or MEPs reside and OAM packets are parsed should report OAM related information such as OAM monitoring results and consequent OAM actions to the EMS/NMS. 4. Each OAM function of a P2MP transport path should be able to be independently configured using the EMS/NMS based on the classification of OAM functional requirements in RFC5860. 5. An on-demand OAM function must be able to perform an OAM function for only a specific target MIP or MEP as well as all MEPs in a P2MP transport path, as specified in Section 3.7 of RFC6371[3]. 6. To manage M leaves(i.e., subset of all leaves) in an on-demand OAM function from the EMS/NMS, a unified mechanism must be provided. Note: Currently, sending an OAM packet that is targeted at a subset of M leaves by using an aggregating mechanism such as an Koike, et al. Expires May 8, 2013 [Page 6] Internet-Draft MPLS-TP p2mp OAM framework November 2012 OAM packet including several MIP or MEP identifiers is out of the scope of RFC6371[3] as described in Section 3.7 of that document. 7. Mismatches of configuration information between a root MEP and any leaf-MEP, at which proactive or on-demand monitoring is enabled, should be detected as a configuration mismatch alarm and be reported to the EMS/NMS by parsing received OAM packets, particularly when a static setting is applied. Generally when each OAM function is enabled, as described in Section 5.1 of RFC6371[3], the source MEP function should be enabled prior to the corresponding sink MEPs function. Regarding configuration considerations, the following are additional requirements for unidirectional P2MP transport path, particularly when RP-HE does not exist. 8. The configuration of each OAM function between the source MEP and sink MEP(s) in an MEG of a transport path should be able to be synchronized using the NMS, when a new P2MP transport path is set. 9. The configuration of newly added/removed specific sink MEP(s)to the existing source MEP in the MEG in proactive monitoring should be able to be synchronized with that of the source MEP by using the NMS. 10.The EMS/NMS should provide a tool for manually configuring consistent values of each piece of configuration information to a root MEP and all the related leaf MEPs in a MEG of a P2MP transport path for both pro-active and on-demand OAM functions. 11.Mismatches of configuration information between a leaf MEP and any other leaf MEP(s) or a root MEP and leaf MEP(s), at which proactive monitoring will be enabled, should be able to be detected through the configuration management process of the EMS/NMS as a configuration mismatch alarm or notification without receiving OAM packets from a source MEP(before OAM functions are enabled). Note: This requirement is not necessary if the EMS/NMS provides a tool to manually configure a consistent value of each piece of configuration information to a root MEP. 12.The enabling or disabling of proactive OAM functions and configuration mismatch alarms of the OAM functions must be independently configurable at each leaf-MEP as well as on all the leaf MEPs on a P2MP transport path, considering maintenances or a Koike, et al. Expires May 8, 2013 [Page 7] Internet-Draft MPLS-TP p2mp OAM framework November 2012 case in which one or more leaf MEPs is newly added or removed later. 13.Mismatches of configuration information between a leaf MEP and any other leaf MEP(s) or a root MEP and leaf MEP(s), at which on- demand OAM monitoring is enabled, must be detected as a configuration management process before conducting OAM functions. 3.2. OAM functions for proactive monitoring The proactive OAM functions are used to detect a fault/defect or to automatically reports a change in the status of a transport path. 3.2.1. Continuity Check and Connectivity Verification(CC-V) The continuity Check function enables one or more leaf MEPs on a unidirectional P2MP transport path to monitor the continuity of OAM packets from root MEP and detect one or more loss of continuity(LOC) defects between the root MEP and leaf MEPs. The connectivity verification function enables one or more leaf MEPs on a P2MP transport path to monitor the connectivity of OAM packets from a specific root MEP and detect an unexpected connectivity defect between two MEGs(two P2MP transport paths) As described in Sections 2.2.2 and 2.2.3 of RFC5860[2], CC-V MUST be supported even when RP-HE does not exist. As described in RFC6371[3], CC-V OAM packets are used for a P2MP transport path. Defect detection mechanisms in P2MP transport paths are the same as those of the P2MP transport path specified in section 5.1.1 of RFC6371 [3]. That is, loss of continuity(LoC) defect, mis- connectivity defect, period mis-configuration defect and unexpected encapsulation defect. Entry and exit criteria are also the same as those of the P2MP transport paths in RFC6371 [3]. However, in a P2MP transport path, all the leaf MEPs that detect a defect must be indentified and differentiated from a normal leaf MEP(s), which does not detect a defect. Configuration is specified in Section 5.1.3 of RFC6371[3]. The following configuration information must be configured: MEG-ID, MEP- ID, list of the other MEPs in the MEG that are different between the root MEP and leaf MEP, PHB for E-LSP and transmission rate. Koike, et al. Expires May 8, 2013 [Page 8] Internet-Draft MPLS-TP p2mp OAM framework November 2012 Consequent actions of a unidirectional P2MP transport path are also covered in Section 5.1.2 of RFC6371 [3]. Operators should be able to enable/disable each consequent action. All MEPs inside a MEG need to be configured and retain the information when a proactive OAM function is enabled, as described in Section 5.1.3 of RFC6371[3]. If there is no RP-HE, it is premised that the EMS/NMS exists. Therefore, the above parameters are statically configured. 3.2.2. Remote Defect Indication This OAM function is not available on a P2MP transport path when return paths do not exist. This OAM function can be implemented only in RP-HE. However, the return path is out of the scope of MPLS-TP requirements. 3.2.3. Alarm Reporting FFS 3.2.4. Lock Reporting For further study(FFS) 3.2.5. Packet Loss Measurement FFS 3.2.6. Packet Delay Measurement FFS 3.2.7. Client Failure Indication FFS 3.3. OAM functions for on-demand monitoring 3.3.1. Connectivity verification The connectivity verification function enables one or more leaf MEPs on a P2MP transport path to monitor the connectivity of OAM packets Koike, et al. Expires May 8, 2013 [Page 9] Internet-Draft MPLS-TP p2mp OAM framework November 2012 from a specific root MEP and detect an unexpected connectivity defect between two MEGs (two P2MP transport paths) 1. Connectivity verification functions MUST be supported when return paths in a unidirectional P2MP transport path do not exist. As described in RFC6371 [3], CC-V OAM packets are used for a P2MP transport path. Defect detection mechanisms in P2MP transport paths are the same as those of the P2MP transport path specified in section 5.1 of RFC6371. That is, loss of continuity defect, mis-connectivity defect, period mis-configuration defect and unexpected encapsulation defect. Entry and exit criteria are also the same as those of the P2MP transport path in RFC6371 [3]. Moreover, consequent actions of a unidirectional P2MP transport path are also covered in Section 5.1.2 of the RFC [3] Regarding configuration consideration, the following additional requirements on a unidirectional P2MP transport path when a return path does not exist. 3.3.2. Packet loss measurement FFS 3.3.3. Diagnostic tests Diagnostic test functions MUST be supported when a return path in a unidirectional P2MP transport path doesn't exist. Other requirements are ffs. 3.3.4. Route Tracing Route tracing function MUST be supported when a return path in a unidirectional P2MP transport path doesn't exist. Other requirements are ffs. 3.3.5. Packet delay measurement FFS Koike, et al. Expires May 8, 2013 [Page 10] Internet-Draft MPLS-TP p2mp OAM framework November 2012 3.4. OAM functions for administration control 3.4.1. Lock Instruct FFS. 4. P2MP Recovery FFS 5. Security Considerations This document does not raise any particular security considerations. 6. IANA Considerations There are no IANA actions required by this draft. 7. References 7.1. Normative References [1] Niven-Jenkins, B., et all, "equirements of an MPLS Transport Profile" RFC5654, September 2009 [2] Vigoureux, M., Betts, M., Ward, D., "Requirements for OAM in MPLS Transport Networks", RFC5860, May 2010 [3] Busi, I., Dave, A. , "Operations, Administration and Maintenance Framework for MPLS-based Transport Networks ", RFC6371, September 2011 [4] Frost, Dan.,et all, "Framework for Point-to-Multipoint MPLS in Transport Networks" draft-fbb-mpls-tp-p2mp-framework-05, August 2012 7.2. Informative References None 8. Acknowledgments The author would like to thank all members (including MPLS-TP steering committee, the Joint Working Team, the MPLS-TP Ad Hoc Group Koike, et al. Expires May 8, 2013 [Page 11] Internet-Draft MPLS-TP p2mp OAM framework November 2012 in ITU-T) involved in the definition and specification of MPLS Transport Profile. This document was prepared using 2-Word-v2.0.template.dot. Authors Addresses Takafumi Hamano NTT hamano.takafumi@lab.ntt.co.jp Masatoshi Namiki NTT namiki.masatoshi@lab.ntt.co.jp Yoshinori Koike NTT Email: koike.yoshinori@lab.ntt.co.jp Koike, et al. Expires May 8, 2013 [Page 12]