Internet DRAFT - draft-hb-pim-p2mp-policy-ping

draft-hb-pim-p2mp-policy-ping







Network Working Group                                    H. Bidgoli, Ed.
Internet-Draft                                                     Nokia
Intended status: Standards Track                                V. Voyer
Expires: January 28, 2021                                    Bell Canada
                                                               P. Parekh
                                                            Cisco System
                                                                Z. Zhang
                                                        Juniper Networks
                                                           July 27, 2020


                            P2MP Policy Ping
                    draft-hb-pim-p2mp-policy-ping-00

Abstract

   SR P2MP policies are set of policies that enable architecture for
   P2MP service delivery.  A P2MP Policy consists of candidate paths
   that connects the Root of the Tree to a set of Leaves.  The P2MP
   policy is composed of replication segments.  A replication segment is
   a forwarding instruction for a candidate path which is downloaded to
   the Root, transit nodes and the leaves.

   This document describes a simple and efficient mechanism that can be
   used to detect data plane failures in P2MP Policy Candidate Paths
   (CPs) and Path Instances (PIs).

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 January 28, 2021.








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Copyright Notice

   Copyright (c) 2020 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
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions used in this document . . . . . . . . . . . . . .   3
   3.  Motivation  . . . . . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  P2MP Policy Ping and Traceroute . . . . . . . . . . . . .   3
     3.2.  Packet format and new TLVs  . . . . . . . . . . . . . . .   3
       3.2.1.  Identifying a P2MP Policy . . . . . . . . . . . . . .   4
         3.2.1.1.  P2MP Policy Sub-TLVs  . . . . . . . . . . . . . .   4
     3.3.  Limiting the Scope of Response  . . . . . . . . . . . . .   5
   4.  Operation of P2MP Policy Ping . . . . . . . . . . . . . . . .   5
     4.1.  Replication Segments Connected via a Unicast SR domain  .   5
   5.  IANA Consideration  . . . . . . . . . . . . . . . . . . . . .   6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   7.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   6
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   Each P2MP Policy can have multiple CPs.  The CP with highest
   preference is the active CP while all other CPs are the backup CPs.
   A CP can have multiple PI to allow global optimization of the CP via
   Make Before Break procedures between the active PI and the newly
   setup and optimized PI.

   This document describes a mechanism that can be used to detect data
   plane failures in P2MP Policy Candidate Paths (CP) and its associate
   Path Instances (PI) from the root to a set of leaves.





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   This draft defines two new sub-TLVs to identifier a P2MP Policy and
   reuses concepts from [RFC6425]

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.  Motivation

   A P2MP Policy and its corresponding Replication Segments are usually
   setup via a PCE, after PCE has calculated the tree from the root to a
   set of leaves.  There is no underlay protocol to signal the P2MP
   Policy from the root to the Leaf routers, as such when a P2MP tree
   fails to deliver user traffic, the failure can be difficult to pin
   point without a ping/traceroute mechanism to isolate the fault in the
   P2MP tree.  The P2MP Policy ping/traceroute can be utilize to detect
   faults on the path of the tree and its associated replication
   segments.  These tools can be used to periodically ping the leaves to
   ensure connectivity.  If the ping fails, trace route can be initiated
   to determine where the failure lies.

3.1.  P2MP Policy Ping and Traceroute

   The P2MP Policy Ping and Traceroute detect failure on the path of
   P2MP Tree and its corresponding replication segments.  Ping/
   Traceroute packets are forwarded on the P2MP Policy, on a specific CP
   or the CP's PI toward the leaf routers.  They are replicated at the
   replication point based on the replication segment information on the
   corresponding transit node.  The packet are processed accordingly
   when their TTL expires or when the egress router (leaf) is reached.
   The appropriate respond is send back to the root as per [RFC6425]

   The implementation should take into account that there can be many CP
   under the P2MP Policy, one active CP and many inactive CPs.  The
   implementation should allow each CP and its corresponding PIs to be
   tested via Ping and Trace route.  The Ping and Traceroute packet is
   forwarded via that specific CP and its corresponding replication
   segments.

3.2.  Packet format and new TLVs

   The packet format used is as per [RFC4379] section 3.







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3.2.1.  Identifying a P2MP Policy

   The new sub-TLV identifiers are assigned, as follow:

   artwork
   Sub-Type       Length            Value Field
   --------       ------            -----------
         38           20            P2MP Policy IPv4 CP
         39           32            P2MP Policy IPv6 CP

3.2.1.1.  P2MP Policy Sub-TLVs

   artwork
       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Address Family         |         Address Length        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      ~                   Root Address (Cont.)                        ~
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        TreeId length          |         Tree-ID      ...      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Path-Instance length    |        Path-instance          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   o  Address Family: Two-octet quantity containing a value from ADDRESS
      FAMILY NUMBERS in [IANA-AF] that encodes the address family for
      the Root LSR Address.

   o  Address Length: Length of the Root LSR Address in octets.

   o  Root Addrt: The address of Root node of P2MP tree instantiated by
      the SR P2MP Policy

   o  TreeId Length: Length of the TreeID in octets.  This should be set
      to 4 octets

   o  Tree-ID: A identifier that is unique in context of the Root.  This
      is an unsigned 32-bit number.

   o  Path-instance Length: Length of the path instance ID in octet.
      This should be set to 2.




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   o  path-instance: path instance ID to be tested

3.3.  Limiting the Scope of Response

   As per [RFC6425] section 3.2 Four sub-TLVs are used for the inclusion
   in the P2MP Responder Identifier TLV carried on the echo request
   message.

   The Sub-TLVs for IPv4 and IPv6 egress address P2MP responder is in
   par with [RFC6425] section 3.2.1

   The Sub-TLVs for IPv4 and IPv6 node address P2MP responder is in par
   with [RFC6425] section 3.2.2

4.  Operation of P2MP Policy Ping

   The P2MP Policy Ping should be able to test the path for all the CPs
   (active or inactive) or the CPs corresponding PIs for a P2MP policy
   on the root router.  In addition it should test all the Out going
   interface for the replication segment connecting the root to the set
   of leaves for this CP or PI.  To do so the concepts in [RFC4379] and
   [RFC6425] are extended to this draft.

   The following sections will explain any new concepts for P2MP policy
   Ping

4.1.  Replication Segments Connected via a Unicast SR domain

   Two replication segment can be connected via a unicast SR domain.
   This means the traffic will be steered out of the upstream
   replication segment based on the unicast SR SID List (as an example
   node or adjacency SIDs).  In this case the replication SID TTL is
   subtracted by one on the current node.  If the TTL hasn't expired,
   the SR SID List will be placed on top of the replication segment,
   with replication segment being at the bottom of the stack.  The SR
   SID List TTL should be set to 255, as an example pipe mode.  When in
   SR domain the TTL of SR SIDs will be decremented accordingly.  The
   TTL of the replication SID will be untouched in the SR domain.  The
   replication SID TTL will be examined again on the next replication
   segment after the unicast SR SID List is removed from the label
   stack.  The appropriate actions will be taken on this replication
   segment for P2MP Policy PING and Traceroute packet.  To detect
   failures in SR domain is beyond the scope of this draft.








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5.  IANA Consideration

   Two new sub-TLV types are defined for inclusion within the LSP ping
   [RFC4379] Target FEC Stack TLV (TLV type 1).

6.  Security Considerations

   TBD

7.  Acknowledgments

8.  References

8.1.  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,
              <https://www.rfc-editor.org/info/rfc2119>.

8.2.  Informative References

   [draft-voyer-pim-sr-p2mp-policy]
              "D. Yoyer, C. Filsfils, R.Prekh, H.bidgoli, Z. Zhang,
              "draft-voyer-pim-sr-p2mp-policy"", October 2019.

   [draft-voyer-spring-sr-replication-segment-04]
              "D. Yoyer, C. Filsfils, R.Prekh, H.bidgoli, Z. Zhang,
              "draft-voyer-pim-sr-p2mp-policy "draft-voyer-spring-sr-
              replication-segment"", July 2020.

   [RFC4379]  "K. Kompella, G. Swallow", February 2006.

   [RFC6425]  "S. Saxena, G. Swallow, Z. Ali, A. Farrel, S. Yasukawa,
              T.Nadeau "Detecting Data-Plane Failures in Point-to-
              Multipoint MPLS"", November 2011.

Authors' Addresses

   Hooman Bidgoli (editor)
   Nokia
   Ottawa
   Canada

   Email: hooman.bidgoli@nokia.com






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   Daniel Voyer
   Bell Canada
   Montreal
   Canada

   Email: daniel.yover@bell.ca


   Rishabh Parekh
   Cisco System
   San Jose
   USA

   Email: riparekh@cisco.com


   Zhaohui Zhang
   Juniper Networks
   Boston
   USA

   Email: zzhang@juniper.com





























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