Internet DRAFT - draft-jain-pwe3-p2mp-pw-lsp-ping

draft-jain-pwe3-p2mp-pw-lsp-ping










     Network Working Group                                   Parag Jain, Ed. 
     Internet Draft                                             Sami Boutros 
     Intended status: Standards Track                    Cisco Systems, Inc. 
     Expires: December 18, 2014                                                                                                     
                                                                  Sam Aldrin 
                                                         Huawei Technologies 
                                                                             
                                                         June 17, 2014 
                                          
                  Definition of P2MP PW TLV for LSP-Ping Mechanisms 
                       draft-jain-pwe3-p2mp-pw-lsp-ping-03.txt                
     Abstract 

        LSP-Ping is a widely deployed Operation, Administration, and 
        Maintenance (OAM) mechanism in MPLS networks. This document 
        describes a mechanism to verify connectivity of Point-to-Multipoint 
        (P2MP) Pseudowires (PW) using LSP Ping. 

      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 
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        This Internet-Draft will expire on December 28, 2011. 

     Copyright Notice 

        Copyright (c) 2011 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 
      
      
      
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        publication of this document.  Please review these documents 
        carefully, as they describe your rights and restrictions with 
        respect to this document. 

         

     Table of Contents 

       1. Introduction                                            2 
       2. Conventions used in this document                       3 
       3. Terminology                                             3 
       4. Identifying a P2MP PW                                   3 
          4.1. FEC 130 Pseudowire Sub-TLV                         4 
       5. Operations                                              4 
       6. Echo Reply using Downstream Assigned Label              6 
       7. Controlling Echo Responses                              6 
       8. Security Considerations                                 6 
       9. IANA Considerations                                     6 
       10. References                                             6 
          10.1. Normative References                              6 
          10.2. Informative References                            7 
       11. Acknowledgments                                        7 
         

     1. Introduction 

        A Point-to-Multipoint (P2MP) Pseudowire (PW) emulates the essential 
        attributes of a unidirectional P2MP Telecommunications service such 
        as P2MP ATM over PSN. Requirements for P2MP PW are described in 
        [PPWREQ]. P2MP PWs are carried over P2MP MPLS LSP. The Procedure for 
        P2MP PW signaling using LDP for single segment P2MP PWs are 
        described in [PPWPWE3]. Many P2MP PWs can share the same P2MP MPLS 
        LSP and this arrangement is called Aggregate P-tree. The aggregate 
        P2MP trees require an upstream assigned label so that on the tail of 
        the P2MP LSP, the traffic can be associated with a VPN or a VPLS 
        instance. When a P2MP MPLS LSP carries only one VPN or VPLS service 
        instance, the arrangement is called Inclusive P-Tree. For Inclusive 
        P-Trees, P2MP MPLS LSP label itself can uniquely identify the VPN or 
        VPLS service being carried over P2MP MPLS LSP. The P2MP MPLS LSP can 
        also be used in Selective P-Tree arrangement for carrying multicast 
        traffic. In a Selective P-Tree arrangement, traffic to each 
        multicast group in a VPN or VPLS instance is carried by a separate 
      
      
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        unique P-tree. In Aggregate Selective P-tree arrangement, traffic to 
        a set of multicast groups from different VPN or VPLS instances is 
        carried over a same shared P-tree.  

        The P2MP MPLS LSP are setup either using MLDP [RFC6388] or P2MP RSVP-TE 
        [RFC4875]. Mechanisms for fault detection and isolation for data 
        plane failures for P2MP MPLS LSPs are specified in [RFC6425]. This 
        document describes a mechanism to detect data plane failures for 
        P2MP PW carried over P2MP MPLS LSPs.  

        This document defines a new FEC 130 Pseudowire sub-TLV for Target 
        FEC Stack for P2MP PW. The FEC 130 Pseudowire sub-TLV is added in 
        Target FEC Stack TLV by the originator of the echo request to inform 
        the receiver at P2MP MPLS LSP tail, of the P2MP PW being tested. 

        Multi-segment Pseudowires support is out of scope of this document 
        at present and may be included in future. 

     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].  

        The term "FEC-Type" is used to refer to a tuple consisting of <FEC 
        Element Type, Address Family>. 

     3. Terminology 

        ATM: Asynchronous Transfer Mode 

        LSR: Label Switching Router 

        MPLS-OAM: MPLS Operations, Administration and Maintenance 

        P2MP-PW: Point-to-Multipoint PseudoWire 

        PW: PseudoWire 

        TLV: Type Length Value 

     4. Identifying a P2MP PW 

        This document introduces a new LSP Ping Target FEC Stack sub-TLV, 
        FEC 130 Pseudowire sub-TLV, to identify the P2MP PW under test at 
        the P2MP LSP Tail/Bud node.  

      
      
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     4.1. FEC 130 Pseudowire Sub-TLV 

        The FEC 130 Pseudowire sub-TLV fields are taken from P2MP PW FEC 
        Element (FEC Type 0x82) defined in [PPWPWE3]. The PW Type is a 15-
        bit number indicating the encapsulation type. It is carried right 
        justified in the field below PW Type with the high-order bit set to 
        zero. All the other fields are treated as opaque values and copied 
        directly from P2MP PW FEC Element (FEC Type 0x82) format.  

        The FEC 130 Pseudowire sub-TLV has the format shown in Figure 1. 
        This TLV will be included in the echo request sent over P2MP PW by 
        the originator of request.  

         

           0                   1                   2                   3 
           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 
           +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
           |0|   PW Type                 |   AGI Type    |   AGI Length    | 
           +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
           ~                          AGI Value                            ~
           |                                                               | 
           +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
           | AII Type    |   SAII Length |           SAII Value            | 
           +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
           ~                     SAII Value (continued)                    ~ 
           |                                                               | 
           +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
                     Figure 1: FEC 130 Pseudowire sub-TLV format 
           

        For Inclusive and Selective P2MP MPLS P-trees, the echo request will 
        be sent using the P2MP MPLS LSP label. 

        For Aggregate Inclusive and Aggregate Selective P-trees, the echo 
        request will be sent using a label stack of <P2MP MPLS P-tree label, 
        upstream assigned P2MP PW label>. The P2MP MPLS P-tree label is the 
        outer label and upstream assigned P2MP PW label is inner label. 

         

     5. Operations 

       In this section, we explain the operation of the LSP Ping over P2MP 
       PW. Figure 2 shows a P2MP PW PW1 setup from T-PE1 to remote PEs (T-
      
      
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       PE2, T-PE3 and T-PE4). The transport LSP associated with the P2MP PW1 
       can be MLDP P2MP MPLS LSP or P2MP TE tunnel. 

        

        

                    |<--------------P2MP PW---------------->| 
             Native |                                       |  Native 
            Service |     |<--PSN1->|      |<--PSN2->|      |  Service 
             (AC)   V     V         V      V         V      V   (AC) 
               |    +-----+         +------+         +------+    | 
               |    |     |         |   P1 |=========|T-PE2 |AC3 |    +---+ 
               |    |     |         |   .......PW1.........>|-------->|CE3| 
               |    |T-PE1|=========|   .  |=========|      |    |    +---+ 
               |    |  .......PW1........  |         +------+    | 
               |    |  .  |=========|   .  |         +------+    | 
               |    |  .  |         |   .  |=========|T-PE3 |AC4 |    +---+ 
       +---+   |AC1 |  .  |         |   .......PW1.........>|-------->|CE4| 
       |CE1|------->|...  |         |      |=========|      |    |    +---+ 
       +---+   |    |  .  |         +------+         +------+    | 
               |    |  .  |         +------+         +------+    | 
               |    |  .  |=========|   P2 |=========|T-PE4 |AC5 |    +---+ 
               |    |  .......PW1..............PW1.........>|-------->|CE5| 
               |    |     |=========|      |=========|      |    |    +---+ 
               |    +-----+         +------+         +------+    | 
                                           
                                  Figure 2: P2MP PW 
        

       When an operator wants to perform a connectivity check for the P2MP 
       PW1, the operator initiate a LSP-Ping request with the Target FEC 
       Stack TLV containing FEC 130 Pseudowire sub-TLV in the echo request 
       packet. The echo request packet is sent over the P2MP MPLS LSP using 
       the P2MP MPLS LSP label for Inclusive P-tree or with a label stack 
       with Upstream assigned P2MP PW label as bottom label and P2MP MPLS 
       LSP label as the top label. The intermediate P router will do swap 
       and replication based on the MPLS LSP label. Once the packet reaches 
       remote terminating PEs, the T-PEs will process the packet and perform 
       checks for the FEC 130 Pseudowire sub-TLV present in the Target FEC 
       Stack TLV as described in Section 4.4 in [RFC4379] and respond 
       according to [RFC4379] processing rules.  

        



      
      
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     6. Echo Reply using Downstream Assigned Label  

        Root of a P2MP PW may send an optional downstream assigned p2p MPLS 
        label in the LDP Label Mapping message for the P2MP PW signaling. If 
        the root of a P2MP PW expects leaf to send echo reply using the 
        downstream assigned label signaled in the Label Mapping message of 
        the P2MP PW message, the Reply Mode value of 4 "Reply via 
        application level control channel" should be used in Reply Mode 
        field described in Section 3 in [RFC4379] in echo request message 
        for the P2MP PW. 

     7. Controlling Echo Responses 

        The procedures described in [RFC6425] for preventing congestion of 
        Echo Responses (Echo Jitter TLV) and limiting the echo reply to a 
        single egress node (Node Address P2MP Responder Identifier TLV) can 
        be applied to P2MP PW LSP Ping. 

     8. Security Considerations 

       The proposal introduced in this document does not introduce any new 
       security considerations beyond that already apply to [RFC6425]. 
        
     9. IANA Considerations 

        This document defines a new sub-TLV type to be included in Target 
        FEC Stack TLV (TLV Type 1) [RFC4379] in LSP Ping.  

        IANA is requested to assign a sub-TLV type value to the following 
        sub-TLV from the "Multiprotocol Label Switching (MPLS) Label 
        Switched Paths (LSPs) Parameters - TLVs" registry, "TLVs and sub-
        TLVs" sub-registry. 

         FEC 130 Pseudowire sub-TLV (See Section 3). Suggested value 24.  

     10. References 

     10.1. Normative References 

        [RFC4379] K. Kompella, G. Swallow, "Detecting Multi-Protocol Label 
                  Switched (MPLS) Data Plane Failures", RFC 4379, February 
                  2006. 

        [PPWPWE3] Martini, L. et. al, "Signaling Root-Initiated Point-to-
                  Multipoint Pseudowires using LDP", draft-ietf-pwe3-p2mp-
                  pw-04.txt, Work in Progress, March 2012. 
      
      
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        [RFC6425] Saxena, S et. Al, "Detecting Data Plane Failures in Point-
                  to-Multipoint Multiprotocol Label Switching (MPLS) - 
                  Extensions to LSP. RFC 6425, November 2011 

     10.2. Informative References 

        [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 
                  Requirement Levels", BCP 14, RFC2119, March 1997. 

        [RFC5085] T. Nadeau, et. al, "Pseudowire Virtual Circuit 
                  Connectivity Verification (VCCV): A Control Channel for 
                  Pseudowires ", RFC 5085, December 2007. 

        [RFC6388] Wijnands, I., Minei, I., Kompella, K., and Thomas, B., 
                  "LDP Extensions for Point-to-Multipoint and Multipoint-to-
                  Multipoint Label Switched Paths", RFC 6388, November 2011. 

        [RFC4875] Aggarwal, R., Papadimitriou, D., and Yasukawa, S., 
                  "Extensions to Resource Reservation Protocol" Traffic 
                  Engineering (RSVP-TE) for Point-to-Multipoint TE Label 
                  Switched Paths (LSPs)", RFC 4875, May 2007. 

        [PPWREQ]  F. Jounay, et. al, "Requirements for Point to Multipoint 
                  Pseudowire", draft-ietf-pwe3-p2mp-pw-requirements-05.txt, 
                  Work in Progress, September 2011. 

          

     11. Acknowledgments 

        The authors would like to thank Shaleen Saxena, Michael Wildt, 
        Tomofumi Hayashi, Danny Prairie for their valuable input and 
        comments. 

        This document was prepared using 2-Word-v2.0.template.dot. 


     Authors' Addresses 

       Parag Jain 
       Cisco Systems, Inc., 
       2000 Innovation Drive, 
       Kanata, ON K2K3E8, Canada. 
       E-mail: paragj@cisco.com 
      
      
      
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       Sami Boutros 
       Cisco Systems, Inc. 
       3750 Cisco Way, 
       San Jose, CA 95134, USA. 
       E-mail: sboutros@cisco.com 
        
       Sam Aldrin 
       Huawei Technologies, co.  
       2330 Central Express Way,  
       Santa Clara, CA 95051, USA.  
       E-mail: aldrin.ietf@gmail.com 

































      
      
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