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Versions: 00 01 02 03 04 draft-ietf-mpls-rfc6374-sfl

MPLS                                                           S. Bryant
Internet-Draft                                                G. Swallow
Intended status: Standards Track                            S. Sivabalan
Expires: April 20, 2016                                    Cisco Systems
                                                               G. Mirsky
                                                                Ericsson
                                                                 M. Chen
                                                                   Z. Li
                                                                  Huawei
                                                        October 18, 2015


                     RFC6374 Synonymous Flow Labels
                    draft-bryant-mpls-rfc6374-sfl-00

Abstract

   This document describes a method of providing flow identification
   information when making RFC6374 performance measurements.  This
   allows RFC6374 measurements to be made on multi-point to point LSPs
   and allows the measurement of flows within an MPLS construct using
   RFC6374.

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."

   This Internet-Draft will expire on April 20, 2016.

Copyright Notice

   Copyright (c) 2015 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.  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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   3.  RFC6374 Packet Loss Measurement with SFL  . . . . . . . . . .   3
     3.1.  RFC6374 SFL TLV . . . . . . . . . . . . . . . . . . . . .   5
   4.  The Application of SFL to other PM Types  . . . . . . . . . .   6
   5.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .   6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   [I-D.bryant-mpls-flow-ident] describes the requirement for
   introducing flow identities when using RFC6374 [RFC6374] packet Loss
   Measurements (LM).  In summary RFC6374 uses the LM packet as the
   packet accounting demarcation point.  Unfortunately this gives rise
   to a number of problems that may lead to significant packet
   accounting errors in certain situations.  For example:

   1.  Where a flow is subjected to Equal Cost Multi-Path (ECMP)
       treatment packets can arrive out of order with respect to the LM
       packet.

   2.  Where a flow is subjected to ECMP treatment, packets can arrive
       at different hardware interfaces, thus requiring reception of an
       LM packet on one interface to trigger a packet accounting action
       on a different interface which may not be co-located with it.
       This is a difficult technical problem to address with the
       required degree of accuracy.

   3.  Even where there is no ECMP (for example on RSVP-TE, MPLS-TP LSPs
       and PWs) local processing may be distributed over a number of
       processor cores, leading to synchronization problems.





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   4.  Link aggregation techniques may also lead to synchronization
       issues.

   5.  Some forwarder implementations have a long pipeline between
       processing a packet and incrementing the associated counter again
       leading to synchronization difficulties.

   An approach to mitigating these synchronization issue is described in
   [I-D.tempia-ippm-p3m] and
   [I-D.chen-ippm-coloring-based-ipfpm-framework] in which packets are
   batched by the sender and each batch is marked in some way such that
   adjacent batches can be easily recognized by the receiver.

   An additional problem arises where the LSP is a multi-point to point
   LSP, since MPLS does not include a source address in the packet.
   Network management operations require the measurement of packet loss
   between a source and destination.  It is thus necessary to introduce
   some source specific information into the packet to identify packet
   batches from a specific source.

   draft-bryant-mpls-sfl-framework specifies a method of encoding per
   flow instructions in an MPLS label stack using a technique called
   Synonymous Flow Labels (SFL) in which labels which mimic the
   behaviour of other labels provide the packet batch identifiers and
   enable the per batch packet accounting.  This memo specifies how SFLs
   are used to perform RFC6374 performance measurements.

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
   [RFC2119].

3.  RFC6374 Packet Loss Measurement with SFL

   The packet format of an RFC6374 Query message using SFLs is shown in
   Figure 1.













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     +-------------------------------+
     |                               |
     |             LSP               |
     |            Label              |
     +-------------------------------+
     |                               |
     |        Synonymous Flow        |
     |            Label              |
     +-------------------------------+
     |                               |
     |                               |
     |  RFC6374 Measurement Message  |
     |                               |
     |  +-------------------------+  |
     |  |                         |  |
     |  |     RFC6374 Fixed       |  |
     |  |     Header              |  |
     |  |                         |  |
     |  +-------------------------+  |
     |  |                         |  |
     |  |      Optional SFL TLV   |  |
     |  |                         |  |
     |  +-------------------------+  |
     |  |                         |  |
     |  |      Optional Return    |  |
     |  |      Information        |  |
     |  |                         |  |
     |  +-------------------------+  |
     |                               |
     +-------------------------------+

                  Figure 1: RFC6734 Query Packet with SFL

   The MPLS label stack is exactly the same as that used for the user
   data service packets being instrumented except for the replacement of
   the appropriate label with an SFL . The RFC6374 measurement message
   consists of the three components, the RFC6374 fixed header as
   specified in [RFC6374] carried over the ACH channel type specified
   the type of measurement being made (currently: loss, delay or loss
   and delay) as specified in RFC6374.

   Two optional TLVs MAY also be carried if needed.  The first is the
   SFL TLV specified in Section 3.1.  This is used to provide the
   implementation with a reminder of the SFL that was used to carry the
   RFC6374 message.  This is needed because a number of MPLS
   implementations do not provide the MPLS label stack to the MPLS OAM
   handler.  This TLV is required if RFC6374 messages are sent over UDP
   (draft-bryant-mpls-RFC6374-over-udp).  This TLV MUST be included



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   unless, by some method outside the scope of this document, it is
   known that this information is not needed by the RFC6374 Responder.

   The second set of information that may be needed is the return
   information that allows the responder send the RFC6374 response to
   the Querier.  This is not needed if the response is requested in-band
   and the MPLS construct being measured is a point to point LSP, but
   otherwise MUST be carried.  The return address TLV is defined in
   RFC6378 and the optional UDP Return Object is defined in
   [I-D.ietf-mpls-rfc6374-udp-return-path].

3.1.  RFC6374 SFL TLV

   [Editor's Note we need to review the following in the light of
   further thoughts on the associated signaling protocol(s).  I am
   fairly confident that we need all the fields other than SFL Batch and
   SFL Index.  The Index is useful in order to map between the label and
   information associated with the FEC.  The batch is part of the
   lifetime management process]

   The required RFC6374 SFL TLV is shown in Figure 2.  This contains the
   SFL that was carried in the label stack, the FEC that was used to
   allocate the SFL and the index into the batch of SLs that were
   allocated for the FEC that corresponds to this SFL.

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    Type       |    Length     |MBZ| SFL Batch |    SFL Index  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                 SFL                   |        Reserved       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                 FEC                                           |
       .                                                               .
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



                             Figure 2: SFL TLV

   Where:

   Type           Type is set to Synonymous Flow Label (SFL-TLV).

   Length         The length of the TLV as specified in [RFC6374].

   MBZ            MUST be sent as zero and ignored on receive.




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   SFL Batch      The SFL batch that this SFL was allocated as part of
                  (see draft-bryant-mpls-sfl-control)

   SPL Index      The index into the list of SFLs that were assigned
                  against the FEC that corresponds to the SFL.

   SFL            The SFL used to deliver this packet.  This is an MPLS
                  label which is a component of a label stack entry as
                  defined in Section 2.1 of [RFC3032].

   Reserved       MUST be sent as zero and ignored on receive.

   FEC            The Forwarding Equivalence Class that was used to
                  request this SFL.  This is encoded as per
                  Section 3.4.1 of

   This information is needed to allow for operation with hardware that
   discards the MPLS label stack before passing the remainder of the
   stack to the OAM handler.  By providing both the SFL and the FEC plus
   index into the array of allocated SFLs a number of implementation
   types are supported.

4.  The Application of SFL to other PM Types

   SFL can be used to enable other types of PM in addition to loss.
   Delay, Delay Variation and Throughput may be calculated based on
   measurement results collected through Loss and Delay Measurement test
   sessions.  Further details will be provided in a future version of
   this draft.

5.  Privacy Considerations

   The inclusion of originating and/or flow information in a packet
   provides more identity information and hence potentially degrades the
   privacy of the communication.  Whilst the inclusion of the additional
   granularity does allow greater insight into the flow characteristics
   it does not specifically identify which node originated the packet
   other than by inspection of the network at the point of ingress, or
   inspection of the control protocol packets.  This privacy threat may
   be mitigated by encrypting the control protocol packets, regularly
   changing the synonymous labels and by concurrently using a number of
   such labels.

6.  Security Considerations

   The issue noted in Section 5 is a security consideration.  There are
   no other new security issues associated with the MPLS dataplane.  Any




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   control protocol used to request SFLs will need to ensure the
   legitimacy of the request.

7.  IANA Considerations

   IANA is request to allocate a new TLV from the 0-127 range on the
   MPLS Loss/Delay Measurement TLV Object Registry:

      Type Description                       Reference
      ---- --------------------------------- ---------
      TBD  Synonymous Flow Label             This

   A value of 4 is recommended.

8.  Acknowledgements

   TBD

9.  References

9.1.  Normative References

   [I-D.ietf-mpls-rfc6374-udp-return-path]
              Bryant, S., Sivabalan, S., and S. Soni, "RFC6374 UDP
              Return Path", draft-ietf-mpls-rfc6374-udp-return-path-04
              (work in progress), August 2015.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC3032]  Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y.,
              Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack
              Encoding", RFC 3032, DOI 10.17487/RFC3032, January 2001,
              <http://www.rfc-editor.org/info/rfc3032>.

9.2.  Informative References

   [I-D.bryant-mpls-flow-ident]
              Bryant, S., Pignataro, C., Chen, M., Li, Z., and G.
              Mirsky, "MPLS Flow Identification", draft-bryant-mpls-
              flow-ident-02 (work in progress), September 2015.








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   [I-D.chen-ippm-coloring-based-ipfpm-framework]
              Chen, M., Zheng, L., Mirsky, G., and G. Fioccola, "IP Flow
              Performance Measurement Framework", draft-chen-ippm-
              coloring-based-ipfpm-framework-04 (work in progress), July
              2015.

   [I-D.tempia-ippm-p3m]
              Capello, A., Cociglio, M., Fioccola, G., Castaldelli, L.,
              and A. Bonda, "A packet based method for passive
              performance monitoring", draft-tempia-ippm-p3m-01 (work in
              progress), September 2015.

   [RFC6374]  Frost, D. and S. Bryant, "Packet Loss and Delay
              Measurement for MPLS Networks", RFC 6374,
              DOI 10.17487/RFC6374, September 2011,
              <http://www.rfc-editor.org/info/rfc6374>.

Authors' Addresses

   Stewart Bryant
   Cisco Systems

   Email: stbryant@cisco.com


   George Swallow
   Cisco Systems

   Email: swallow@cisco.com


   Siva Sivabalan
   Cisco Systems

   Email: msiva@cisco.com


   Greg Mirsky
   Ericsson

   Email: gregory.mirsky@ericsson.com


   Mach(Guoyi) Chen
   Huawei

   Email: mach.chen@huawei.com




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   Zhenbin(Robin)  Li
   Huawei

   Email: lizhenbin@huawei.com















































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