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BIER  Working Group                                            G. Mirsky
Internet-Draft                                                 ZTE Corp.
Intended status: Standards Track                                L. Zheng
Expires: June 13, 2019                                           M. Chen
                                                     Huawei Technologies
                                                             G. Fioccola
                                                          Telecom Italia
                                                       December 10, 2018


 Performance Measurement (PM) with Marking Method in Bit Index Explicit
                        Replication (BIER) Layer
                      draft-ietf-bier-pmmm-oam-05

Abstract

   This document describes a hybrid performance measurement method for
   multicast service over Bit Index Explicit Replication (BIER) domain.

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
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   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   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 June 13, 2019.

Copyright Notice

   Copyright (c) 2018 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
   (https://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



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   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 . . . . . . . . . . . . . .   2
     2.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   2
     2.2.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   3.  OAM Field in BIER Header  . . . . . . . . . . . . . . . . . .   3
   4.  Theory of Operation . . . . . . . . . . . . . . . . . . . . .   3
     4.1.  Single Mark Enabled Measurement . . . . . . . . . . . . .   4
     4.2.  Double Mark Enabled Measurement . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   7.  Acknowledgement . . . . . . . . . . . . . . . . . . . . . . .   6
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   [RFC8279] introduces and explains Bit Index Explicit Replication
   (BIER) architecture and how it supports forwarding of multicast data
   packets.  [RFC8296] specified that in case of BIER encapsulation in
   MPLS network a BIER-MPLS label, the label that is at the bottom of
   the label stack, uniquely identifies the multicast flow.  [RFC8321]
   describes hybrid performance measurement method, per [RFC7799]
   classification of measurement methods.  Packet Network Performance
   Monitoring (PNPM), which can be used to measure packet loss, latency,
   and jitter on live traffic.  Because this method is based on marking
   consecutive batches of packets the method often referred to as
   Marking Method (MM).

   This document defines how marking method can be used on BIER layer to
   measure packet loss and delay metrics of a multicast flow in MPLS
   network.

2.  Conventions used in this document

2.1.  Terminology

   BFR: Bit-Forwarding Router

   BFER: Bit-Forwarding Egress Router

   BFIR: Bit-Forwarding Ingress Router



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   BIER: Bit Index Explicit Replication

   MM: Marking Method

   OAM: Operations, Administration and Maintenance

2.2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

3.  OAM Field in BIER Header

   [RFC8296] defined the two-bit long field, referred to as OAM,
   designated for the marking performance measurement method.  The OAM
   field MUST NOT be used in defining forwarding and/or quality of
   service treatment of a BIER packet.  The OAM field MUST be used only
   for the performance measurement of data traffic in BIER layer.
   Because the setting of the field to any value does not affect
   forwarding and/or quality of service treatment of a packet, the
   marking method in BIER layer can be viewed as the example of the
   hybrid performance measurement method.

   The Figure 1 displays format of the OAM field

    0
    0   1
   +-+-+-+-+
   | L | D |
   +-+-+-+-+

                 Figure 1: OAM field of BIER Header format

   where:

   o  L - Loss flag;

   o  D - Delay flag.

4.  Theory of Operation

   The marking method can be successfully used in the multicast
   environment supported by BIER layer.  Without limiting any generality
   consider multicast network presented in Figure 2.  Any combination of
   markings, Loss and/or Delay, can be applied to a multicast flow by



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   any Bit Forwarding Router (BFR) at either ingress or egress point to
   perform node, link, segment or end-to-end measurement to detect
   performance degradation defect and localize it efficiently.


                           -----
                         --| D |
                 -----  /  -----
               --| B |--
              /  -----  \  -----
             /           --| E |
   -----    /              -----
   | A |---                -----
   -----    \            --| F |
             \  -----   /  -----
              --| C |--
                -----   \  -----
                         --| G |
                           -----


                        Figure 2: Multicast network

   Using the marking method, a BFR creates distinct sub-flows in the
   particular multicast traffic over BIER layer.  Each sub-flow consists
   of consecutive blocks, consisting of identically marked packets, that
   are unambiguously recognizable by a monitoring point at any BFR and
   can be measured to calculate packet loss and/or packet delay metrics.
   It is expected that the marking values be set and cleared at the edge
   of BIER domain.  Thus for the scenario presented in Figure 2 if the
   operator initially monitors A-C-G and A-B-D segments he may enable
   measurements on segments C-F and B-E at any time.

4.1.  Single Mark Enabled Measurement

   As explained in the [RFC8321], marking can be applied to delineate
   blocks of packets based either on the equal number of packets in a
   block or based on equal time interval.  The latter method offers
   better control as it allows better account for capabilities of
   downstream nodes to report statistics related to batches of packets
   and, at the same time, time resolution that affects defect detection
   interval.

   If the Single Mark measurement used to measure packet loss, then the
   D flag MUST be set to zero on transmit and ignored by monitoring
   point.





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   The L flag is used to create alternate flows to measure the packet
   loss by switching the value of the L flag every N-th packet or at
   certain time intervals.  Delay metrics MAY be calculated with the
   alternate flow using any of the following methods:

   o  First/Last Packet Delay calculation: whenever the marking, i.e.
      value of L flag changes, a BFR can store the timestamp of the
      first/last packet of the block.  The timestamp can be compared
      with the timestamp of the packet that arrived in the same order
      through a monitoring point at downstream BFR to compute packet
      delay.  Because timestamps collected based on order of arrival
      this method is sensitive to packet loss and re-ordering of packets

   o  Average Packet Delay calculation: an average delay is calculated
      by considering the average arrival time of the packets within a
      single block.  A BFR may collect timestamps for each packet
      received within a single block.  Average of the timestamp is the
      sum of all the timestamps divided by the total number of packets
      received.  Then the difference between averages calculated at two
      monitoring points is the average packet delay on that segment.
      This method is robust to out of order packets and also to packet
      loss (only a small error is introduced).  This method only
      provides a single metric for the duration of the block and it
      doesn't give the minimum and maximum delay values.  This
      limitation could be overcome by reducing the duration of the block
      by means of a highly optimized implementation of the method.

4.2.  Double Mark Enabled Measurement

   Double Mark method allows measurement of minimum and maximum delays
   for the monitored flow but it requires more nodal and network
   resources.  If the Double Mark method used, then the L flag MUST be
   used to create the alternate flow, i.e. mark larger batches of
   packets.  The D flag MUST be used to mark single packets to measure
   delay jitter.

   The first marking (L flag alternation) is needed for packet loss and
   also for average delay measurement.  The second marking (D flag is
   put to one) creates a new set of marked packets that are fully
   identified over the BIER network, so that a BFR can store the
   timestamps of these packets; these timestamps can be compared with
   the timestamps of the same packets on a second BFR to compute packet
   delay values for each packet.  The number of measurements can be
   easily increased by changing the frequency of the second marking.
   But the frequency of the second marking must be not too high in order
   to avoid out of order issues.  This method is useful to measure not
   only the average delay but also the minimum and maximum delay values




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   and, in wider terms, to know more about the statistic distribution of
   delay values.

5.  IANA Considerations

   This document requests IANA to register format of the OAM field of
   BIER Header as the following:

   +--------------+---------+--------------------------+---------------+
   | Bit Position | Marking | Description              | Reference     |
   +--------------+---------+--------------------------+---------------+
   |      0       |    S    | Single Mark Measurement  | This document |
   |      1       |    D    | Double Mark Measurement  | This document |
   +--------------+---------+--------------------------+---------------+

                     Table 1: OAM field of BIER Header

6.  Security Considerations

   This document list the OAM requirement for BIER-enabled domain and
   does not raise any security concerns or issues in addition to ones
   common to networking.

7.  Acknowledgement

   TBD

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>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8296]  Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A.,
              Tantsura, J., Aldrin, S., and I. Meilik, "Encapsulation
              for Bit Index Explicit Replication (BIER) in MPLS and Non-
              MPLS Networks", RFC 8296, DOI 10.17487/RFC8296, January
              2018, <https://www.rfc-editor.org/info/rfc8296>.






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8.2.  Informative References

   [RFC7799]  Morton, A., "Active and Passive Metrics and Methods (with
              Hybrid Types In-Between)", RFC 7799, DOI 10.17487/RFC7799,
              May 2016, <https://www.rfc-editor.org/info/rfc7799>.

   [RFC8279]  Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A.,
              Przygienda, T., and S. Aldrin, "Multicast Using Bit Index
              Explicit Replication (BIER)", RFC 8279,
              DOI 10.17487/RFC8279, November 2017,
              <https://www.rfc-editor.org/info/rfc8279>.

   [RFC8321]  Fioccola, G., Ed., Capello, A., Cociglio, M., Castaldelli,
              L., Chen, M., Zheng, L., Mirsky, G., and T. Mizrahi,
              "Alternate-Marking Method for Passive and Hybrid
              Performance Monitoring", RFC 8321, DOI 10.17487/RFC8321,
              January 2018, <https://www.rfc-editor.org/info/rfc8321>.

Authors' Addresses

   Greg Mirsky
   ZTE Corp.

   Email: gregimirsky@gmail.com


   Lianshu Zheng
   Huawei Technologies

   Email: vero.zheng@huawei.com


   Mach Chen
   Huawei Technologies

   Email: mach.chen@huawei.com


   Giuseppe Fioccola
   Telecom Italia

   Email: giuseppe.fioccola@telecomitalia.it









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