[Docs] [txt|pdf] [Tracker] [Email] [Diff1] [Diff2] [Nits]

Versions: (draft-gandhi-spring-sr-mpls-pm) 00 01

SPRING Working Group                                      R. Gandhi, Ed.
Internet-Draft                                               C. Filsfils
Intended Status: Informational                       Cisco Systems, Inc.
Expires: August 18, 2019                                        D. Voyer
                                                             Bell Canada
                                                              S. Salsano
                                        Universita di Roma "Tor Vergata"
                                                            P. L. Ventre
                                                                    CNIT
                                                                 M. Chen
                                                                  Huawei
                                                       February 14, 2019


                   In-band Performance Measurement for
              Segment Routing Networks with MPLS Data Plane
                draft-gandhi-spring-rfc6374-srpm-mpls-00

Abstract

   RFC 6374 specifies protocol mechanisms to enable the efficient and
   accurate measurement of packet loss, one-way and two-way delay, as
   well as related metrics such as delay variation in MPLS networks
   using probe messages.  This document reviews how these mechanisms can
   be used for Delay and Loss Performance Measurements (PM) in Segment
   Routing (SR) networks with MPLS data plane (SR-MPLS), for both SR
   links and end-to-end SR Policies.  The performance measurements for
   SR links are used to compute extended Traffic Engineering (TE)
   metrics for delay and loss and are advertised in the network using
   the routing protocol extensions.


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."





Gandhi, et al.          Expires August 18, 2019                 [Page 1]


Internet-Draft            RFC 6374 for SR-MPLS         February 14, 2019


Copyright Notice

   Copyright (c) 2019 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
   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 . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Conventions Used in This Document  . . . . . . . . . . . . . .  3
     2.1.  Abbreviations  . . . . . . . . . . . . . . . . . . . . . .  3
     2.2.  Reference Topology . . . . . . . . . . . . . . . . . . . .  4
     2.3.  In-band Probe Messages . . . . . . . . . . . . . . . . . .  5
   3.  Probe Query and Response Packets . . . . . . . . . . . . . . .  5
     3.1.  Probe Packet Header for SR-MPLS Policies . . . . . . . . .  5
     3.2.  Probe Packet Header for SR-MPLS Links  . . . . . . . . . .  6
     3.3.  Probe Response Message for SR-MPLS Links and Policies  . .  6
       3.3.1.  One-way Measurement Probe Response Message . . . . . .  6
       3.3.2.  Two-way Measurement Probe Response Message . . . . . .  6
   4.  Performance Delay Measurement  . . . . . . . . . . . . . . . .  7
     4.1.  Delay Measurement Message Format . . . . . . . . . . . . .  7
     4.2.  Timestamps . . . . . . . . . . . . . . . . . . . . . . . .  7
   5.  Performance Loss Measurement . . . . . . . . . . . . . . . . .  7
     5.1.  Loss Measurement Message Format  . . . . . . . . . . . . .  8
   6.  Performance Measurement for P2MP SR Policies . . . . . . . . .  8
   7.  ECMP for SR-MPLS Policies  . . . . . . . . . . . . . . . . . .  8
   8.  SR Link Extended TE Metrics Advertisements . . . . . . . . . .  8
   9.  Security Considerations  . . . . . . . . . . . . . . . . . . .  9
   10.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  9
   11.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  9
     11.1.  Normative References  . . . . . . . . . . . . . . . . . .  9
     11.2.  Informative References  . . . . . . . . . . . . . . . . .  9
   Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . . . 11
   Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11





Gandhi, et al.          Expires August 18, 2019                 [Page 2]


Internet-Draft            RFC 6374 for SR-MPLS         February 14, 2019


1.  Introduction

   Service provider's ability to satisfy Service Level Agreements (SLAs)
   depend on the ability to measure and monitor performance metrics for
   packet loss and one-way and two-way delay, as well as related metrics
   such as delay variation.  The ability to monitor these performance
   metrics also provides operators with greater visibility into the
   performance characteristics of their networks, thereby facilitating
   planning, troubleshooting, and network performance evaluation.

   [RFC6374] specifies protocol mechanisms to enable the efficient and
   accurate measurement of performance metrics in MPLS networks using
   probe messages.  The One-Way Active Measurement Protocol (OWAMP)
   defined in [RFC4656] and Two-Way Active Measurement Protocol (TWAMP)
   defined in [RFC5357] provide capabilities for the measurement of
   various performance metrics in IP networks.  However, mechanisms
   defined in [RFC6374] are more suitable for Segment Routing (SR) when
   using MPLS data plane (SR-MPLS).  The [RFC6374] also supports IEEE
   1588 timestamps [IEEE1588] and "direct mode" Loss Measurement (LM),
   which are required in SR networks.

   [RFC7876] specifies the procedures to be used when sending and
   processing out-of-band performance measurement probe replies over an
   UDP return path when receiving RFC 6374 based probe queries.  These
   procedures can be used to send out-of-band PM replies for both SR
   links and SR Policies [I-D.spring-segment-routing-policy] for one-way
   measurement.

   This document reviews how probe based mechanisms defined in [RFC6374]
   can be used for Delay and Loss Performance Measurements (PM) in SR
   networks with MPLS data plane, for both SR links and end-to-end SR
   Policies.  The performance measurements for SR links are used to
   compute extended Traffic Engineering (TE) metrics for delay and loss
   and are advertised in the network using routing protocol extensions.


2.  Conventions Used in This Document

2.1.  Abbreviations

   ACH: Associated Channel Header.

   DM: Delay Measurement.

   ECMP: Equal Cost Multi-Path.

   G-ACh: Generic Associated Channel (G-ACh).




Gandhi, et al.          Expires August 18, 2019                 [Page 3]


Internet-Draft            RFC 6374 for SR-MPLS         February 14, 2019


   GAL: Generic Associated Channel (G-ACh) Label.

   LM: Loss Measurement.

   MPLS: Multiprotocol Label Switching.

   NTP: Network Time Protocol.

   PM: Performance Measurement.

   PSID: Path Segment Identifier.

   PTP: Precision Time Protocol.

   SID: Segment ID.

   SL: Segment List.

   SR: Segment Routing.

   SR-MPLS: Segment Routing with MPLS data plane.

   TC: Traffic Class.

   TE: Traffic Engineering.

   URO: UDP Return Object.


2.2.  Reference Topology

   In the reference topology shown in Figure 1, the querier node R1
   initiates a performance measurement probe query and the responder
   node R5 sends a probe response for the query message received.  The
   probe response is typically sent to the querier node R1.  The nodes
   R1 and R5 may be directly connected via a link enabled with Segment
   Routing or there exists a Point-to-Point (P2P) SR Policy
   [I-D.spring-segment-routing-policy] on node R1 with destination to
   node R5.  In case of Point-to-Multipoint (P2MP), SR Policy
   originating from source node R1 may terminate on multiple destination
   leaf nodes [I-D.spring-sr-p2mp-policy].


             +-------+        Query        +-------+
             |       | - - - - - - - - - ->|       |
             |   R1  |---------------------|   R5  |
             |       |<- - - - - - - - - - |       |
             +-------+       Response      +-------+



Gandhi, et al.          Expires August 18, 2019                 [Page 4]


Internet-Draft            RFC 6374 for SR-MPLS         February 14, 2019


                   Figure 1: Reference Topology

   Both delay and loss performance measurement is performed in-band for
   the traffic traversing between node R1 and node R5.  One-way delay
   and two-way delay measurements are defined in Section 2.4 of
   [RFC6374].  Transmit and Receive packet loss measurements are defined
   in Section 2.2 and Section 2.6 of [RFC6374].  One-way loss
   measurement provides receive packet loss whereas two-way loss
   measurement provides both transmit and receive packet loss.

2.3.  In-band Probe Messages

   For both Delay and Loss measurements for links and SR Policies, no PM
   session is created on the responder node.  The probe messages for
   Delay measurement are sent in-band by the querier node to measure the
   delay experienced by the actual traffic flowing on the links and SR
   Policies.  For Loss measurement, in-band probe messages are used to
   collect the traffic counter for the incoming link or incoming SID on
   which the probe query message is received at the responder node R5
   (as it has no PM session state present on the node).

3.  Probe Query and Response Packets

3.1.  Probe Packet Header for SR-MPLS Policies

   As described in Section 2.9.1 of [RFC6374], MPLS PM probe query and
   response messages flow over the MPLS Generic Associated Channel (G-
   ACh).  A probe packet for an end-to-end measurement for SR Policy
   contains SR-MPLS label stack [I-D.spring-segment-routing-policy],
   with the G-ACh Label (GAL) at the bottom of the stack.  The GAL is
   followed by an Associated Channel Header (ACH), which identifies the
   message type and the message payload following the ACH as shown in
   Figure 2.

    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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                  Label(0)             | TC  |S|      TTL      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    .                                                               .
    .                                                               .
    .                                                               .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                  Label(n)             | TC  |S|      TTL      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                  GAL (value 13)       | TC  |S|      TTL      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |0 0 0 1|Version|  Reserved     | GAL Channel Type              |



Gandhi, et al.          Expires August 18, 2019                 [Page 5]


Internet-Draft            RFC 6374 for SR-MPLS         February 14, 2019


    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     Figure 2: Probe Packet Header for an End-to-end SR-MPLS Policy

   The SR-MPLS label stack can be empty to indicate Implicit NULL label
   case.

3.2.  Probe Packet Header for SR-MPLS Links

   As described in Section 2.9.1 of [RFC6374], MPLS PM probe query and
   response messages flow over the MPLS Generic Associated Channel
   (G-ACh).  A probe packet for SR-MPLS links contains G-ACh Label
   (GAL).  The GAL is followed by an Associated Channel Header (ACH),
   which identifies the message type, and the message payload following
   the ACH as shown in Figure 3.

    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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |             GAL (value 13)            | TC  |S|      TTL      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |0 0 0 1|Version|  Reserved     | GAL Channel Type              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

            Figure 3: Probe Packet Header for an SR-MPLS Link


3.3.  Probe Response Message for SR-MPLS Links and Policies

3.3.1.  One-way Measurement Probe Response Message

   For one-way performance measurement [RFC7679], the PM querier node
   can receive "out-of-band" probe replies by properly setting the UDP
   Return Object (URO) TLV in the probe query message.  The URO TLV
   (Type=131) is defined in [RFC7876] and includes the
   UDP-Destination-Port and IP Address.  In particular, if the querier
   sets its own IP address in the URO TLV, the probe response is sent
   back by the responder node to the querier node.  In addition, the
   "control code" in the probe query message is set to "out-of-band
   response requested".  The "Source Address" TLV (Type 130), and
   "Return Address" TLV (Type 1), if present in the probe query message,
   are not used to send probe response message.

3.3.2.  Two-way Measurement Probe Response Message

   For two-way performance measurement [RFC6374], when using a
   bidirectional channel, the probe response message is sent back to the
   querier node in-band on the reverse direction SR Link or SR Policy



Gandhi, et al.          Expires August 18, 2019                 [Page 6]


Internet-Draft            RFC 6374 for SR-MPLS         February 14, 2019


   using a message with format similar to their probe query message.  In
   this case, the "control code" in the probe query message is set to
   "in-band response requested".

   A Path Segment Identifier [I-D.spring-mpls-path-segment] of the
   forward SR Policy can be used to find the reverse SR Policy and to
   send back the probe response message.


4.  Performance Delay Measurement

4.1.  Delay Measurement Message Format

   As defined in [RFC6374], MPLS DM probe query and response messages
   use Associated Channel Header (ACH) (value 0x000C for delay
   measurement) [RFC6374], which identifies the message type, and the
   message payload following the ACH.  For both SR links and end-to-end
   measurement for SR Policies, the same MPLS DM ACH value is used.

   The DM message payload as defined in Section 3.2 of [RFC6374] is used
   for SR-MPLS delay measurement, for both SR links and end-to-end SR
   Policies.

4.2.  Timestamps

   The Section 3.4 of [RFC6374] defines timestamp format that can be
   used for delay measurement.  The IEEE 1588 Precision Time Protocol
   (PTP) timestamp format [IEEE1588] is used by default as described in
   Appendix A of [RFC6374], but it may require hardware support.  As an
   alternative, Network Time Protocol (NTP) timestamp format can also be
   used [RFC6374].

   Note that for one-way delay measurement, clock synchronization
   between the querier and responder nodes using the methods detailed in
   [RFC6374] is required.  The two-way delay measurement does not
   require clock synchronization between the querier and responder
   nodes.


5.  Performance Loss Measurement

   The LM protocol can perform two distinct kinds of loss measurement as
   described in Section 2.9.8 of [RFC6374].

   o  In inferred mode, LM will measure the loss of specially generated
      test messages in order to infer the approximate data plane loss
      level.  Inferred mode LM provides only approximate loss
      accounting.



Gandhi, et al.          Expires August 18, 2019                 [Page 7]


Internet-Draft            RFC 6374 for SR-MPLS         February 14, 2019


   o  In direct mode, LM will directly measure data plane packet loss.
      Direct mode LM provides perfect loss accounting, but may require
      hardware support.

   For both of these modes of LM, Path Segment Identifier (PSID)
   [I-D.spring-mpls-path-segment] is used for accounting received
   traffic on the egress node of the SR-MPLS Policy.

5.1.  Loss Measurement Message Format

   As defined in [RFC6374], MPLS LM probe query and response messages
   use Associated Channel Header (ACH) (value 0x000A for direct loss
   measurement or value 0x000B for inferred loss measurement), which
   identifies the message type, and the message payload following the
   ACH.  For both SR links and end-to-end measurement for SR Policies,
   the same MPLS LM ACH value is used.

   The LM message payload as defined in Section 3.1 of [RFC6374] is used
   for SR-MPLS loss measurement, for both SR links and end-to-end SR
   Policies.


6.  Performance Measurement for P2MP SR Policies

   The procedures for delay and loss measurement reviewed in this
   document for Point-to-Point (P2P) SR-MPLS Policies are also equally
   applicable to the Point-to-Multipoint (P2MP) SR Policies.

   The responder node adds the "Source Address" TLV (Type 130) [RFC6374]
   in the probe response message.  This TLV allows the querier node to
   identify the responder nodes of the P2MP SR Policy.


7.  ECMP for SR-MPLS Policies

   An SR Policy can have ECMPs between the source and transit nodes,
   between transit nodes and between transit and destination nodes.
   Usage of Anycast SID [RFC8402] by an SR Policy can result in ECMP
   paths via transit nodes part of that Anycast group.  The PM messages
   using [RFC6374] can not traverse all ECMP paths to measure
   performance delay of all paths of an SR Policy.


8.  SR Link Extended TE Metrics Advertisements

   The extended TE metrics for SR link delay and loss computed using the
   performance measurement procedures reviewed in this document can be
   advertised in the routing domain as follows:



Gandhi, et al.          Expires August 18, 2019                 [Page 8]


Internet-Draft            RFC 6374 for SR-MPLS         February 14, 2019


   o  For OSPF, ISIS, and BGP-LS, protocol extensions defined in
      [RFC7471], [RFC7810] [I-D.lsr-isis-rfc7810bis], and
      [I-D.idr-te-pm-bgp] are used, respectively for advertising the
      extended TE link metrics in the network.

   o  The extended TE link delay metrics advertised are minimum-delay,
      maximum-delay, average-delay, and delay-variance for one-way.

   o  The delay-variance metric is computed as specified in Section 4.2
      of [RFC5481].

   o  The one-way delay metrics can be computed using two-way
      measurement by dividing the measured delay values by 2.

   o  The extended TE link loss metric advertised is one-way percentage
      packet loss.


9.  Security Considerations

   This document reviews the procedures for performance delay and loss
   measurement for SR-MPLS networks, for both links and end-to-end SR
   Policies using the mechanisms defined in [RFC6374].  This document
   does not introduce any additional security considerations other than
   those covered in [RFC6374], [RFC7471], [RFC7810], and [RFC7876].


10.  IANA Considerations

   This document does not require any IANA actions.


11.  References

11.1.  Normative References

   [RFC6374]  Frost, D. and S. Bryant, "Packet Loss and Delay
              Measurement for MPLS networks', RFC 6374, September 2011.

   [RFC7876]  Bryant, S., Sivabalan, S., and Soni, S., "UDP Return Path
              for Packet Loss and Delay Measurement for MPLS Networks",
              RFC 7876, July 2016.

11.2.  Informative References

   [IEEE1588] IEEE, "1588-2008 IEEE Standard for a Precision Clock
              Synchronization Protocol for Networked Measurement and
              Control Systems", March 2008.



Gandhi, et al.          Expires August 18, 2019                 [Page 9]


Internet-Draft            RFC 6374 for SR-MPLS         February 14, 2019


   [RFC4656]  Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M.
              Zekauskas, "A One-way Active Measurement Protocol
              (OWAMP)", RFC 4656, September 2006.

   [RFC5357]  Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J.
              Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)",
              RFC 5357, October 2008.

   [RFC5481]  Morton, A. and B. Claise, "Packet Delay Variation
              Applicability Statement", RFC 5481, March 2009.

   [RFC7679]  Almes, G., et al., "A One-Way Delay Metric for IP
              Performance Metrics (IPPM)', RFC 7679, January 2016.

   [RFC7471]  Giacalone, S., et al., "OSPF Traffic Engineering (TE)
              Metric Extensions", RFC 7471, March 2015.

   [RFC7810]  Previdi, S., et al., "IS-IS Traffic Engineering (TE)
              Metric Extensions", RFC 7810, May 2016.

   [RFC8402]  Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
              Decraene, B., Litkowski, S., and R. Shakir, "Segment
              Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
              July 2018, <https://www.rfc-editor.org/info/rfc8402>.

   [I-D.lsr-isis-rfc7810bis]  Ginsberg, L., et al., "IS-IS Traffic
              Engineering (TE) Metric Extensions",
              draft-ietf-lsr-isis-rfc7810bis, work in progress.

   [I-D.idr-te-pm-bgp]  Ginsberg, L. Ed., et al., "BGP-LS Advertisement
              of IGP Traffic Engineering Performance Metric Extensions",
              draft-ietf-idr-te-pm-bgp, work in progress.

   [I-D.spring-segment-routing-policy]  Filsfils, C., et al., "Segment
              Routing Policy Architecture",
              draft-ietf-spring-segment-routing-policy, work in
              progress.

   [I-D.spring-sr-p2mp-policy]  Voyer, D. Ed., et al., "SR Replication
              Policy for P2MP Service Delivery",
              draft-voyer-spring-sr-p2mp-policy, work in progress.

   [I-D.spring-mpls-path-segment]  Cheng, W., et al., "Path Segment in
              MPLS Based Segment Routing Network",
              draft-cheng-spring-mpls-path-segment, work in progress.






Gandhi, et al.          Expires August 18, 2019                [Page 10]


Internet-Draft            RFC 6374 for SR-MPLS         February 14, 2019


Acknowledgments

   The authors would like to thank Greg Mirsky for providing many useful
   comments and suggestions.


Contributors

   Sagar Soni
   Cisco Systems, Inc.
   Email: sagsoni@cisco.com


   Patrick Khordoc
   Cisco Systems, Inc.
   Email: pkhordoc@cisco.com


   Zafar Ali
   Cisco Systems, Inc.
   Email: zali@cisco.com



Authors' Addresses

   Rakesh Gandhi (editor)
   Cisco Systems, Inc.
   Canada
   Email: rgandhi@cisco.com


   Clarence Filsfils
   Cisco Systems, Inc.
   Email: cfilsfil@cisco.com


   Daniel Voyer
   Bell Canada
   Email: daniel.voyer@bell.ca


   Stefano Salsano
   Universita di Roma "Tor Vergata"
   Italy
   Email: stefano.salsano@uniroma2.it





Gandhi, et al.          Expires August 18, 2019                [Page 11]


Internet-Draft            RFC 6374 for SR-MPLS         February 14, 2019


   Pier Luigi Ventre
   CNIT
   Italy
   Email: pierluigi.ventre@cnit.it


   Mach(Guoyi) Chen
   Huawei
   Email: mach.chen@huawei.com










































Gandhi, et al.          Expires August 18, 2019                [Page 12]


Html markup produced by rfcmarkup 1.129c, available from https://tools.ietf.org/tools/rfcmarkup/