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Versions: 00 01 02 03 04 draft-ietf-ippm-type-p-monitor

Network Working Group                                           J. Hedin
Internet-Draft                                                 G. Mirsky
Intended status: Standards Track                         S.  Baillargeon
Expires: April 3, 2015                                          Ericsson
                                                      September 30, 2014


 Differentiated Service Code Point and Explicit Congestion Notification
       Monitoring in Two-Way Active Measurement Protocol (TWAMP)
                   draft-hedin-ippm-type-p-monitor-04

Abstract

   This document describes an OPTIONAL feature for TWAMP [RFC5357]
   allowing the monitoring of the Differentiated Service Code Point and
   Explicit Congestion Notification fields with the TWAMP-Test protocol.

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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   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 3, 2015.

Copyright Notice

   Copyright (c) 2014 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   described in the Simplified BSD License.



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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Conventions used in this document . . . . . . . . . . . .   3
       1.1.1.  Terminology . . . . . . . . . . . . . . . . . . . . .   3
       1.1.2.  Requirements Language . . . . . . . . . . . . . . . .   3
   2.  TWAMP Extensions  . . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Setting Up Connection to Monitor DSCP and ECN . . . . . .   3
     2.2.  TWAMP-Test Extension  . . . . . . . . . . . . . . . . . .   4
       2.2.1.  Session-Reflector Packet Format for DSCP and ECN
               Monitoring  . . . . . . . . . . . . . . . . . . . . .   4
       2.2.2.  DSCP and ECN Monitoring with RFC 6038 extensions  . .   7
       2.2.3.  Consideration for TWAMP Light mode  . . . . . . . . .   8
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   9
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   One-Way Active Measurement Protocol (OWAMP) [RFC4656] defines Type-P
   descriptor and negotiation of its value in OWAMP-Control protocol.
   Two-Way Active Measurement Protocol (TWAMP) [RFC5357] states that
   only Differentiated Service Code Point (DSCP) value can be defined by
   Type-P descriptor and the negotiated value must be used by both
   Session-Sender and Session-Reflector.  The TWAMP specification also
   states that the same value of DSCP (found in the Session-Sender
   packet) MUST be used in the test packet reflected by the Session-
   Reflector.  However the TWAMP-Test protocol does not specify any
   methods to determine or report when the DSCP value has changed or is
   different than expected in the forward or reverse direction.  Re-
   marking the DSCP (changing its original value) in IP networks is
   possible and often accomplished by a Diffserv policy configured o a
   single node along the IP path.  In many cases, a change of the DSCP
   value of indicates an unintentional or errorneous behavior.  At best,
   the Session-Sender can detect a change of the DSCP reverse direction
   assuming such change is actually detectable.

   This document describes an OPTIONAL feature for TWAMP.  It is called
   the DSCP and ECN monitoring feature.  This feature allows the
   Session-Sender to know the actual DSCP value received at the Session-
   Reflector.  Furthermore this OPTIONAL feature also tracks the
   Explicit Congestion Notification (ECN) value received at the Session-
   Reflector.  This is helpful to determine if ECN is actually operating




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   or if an ECN-capable node has detected congestion in the forward
   direction.

1.1.  Conventions used in this document

1.1.1.  Terminology

   DSCP: Differentiated Service Codepoint

   ECN: Explicit Congestion Notification

   IPPM: IP Performance Measurement

   TWAMP: Two-Way Active Measuremnt Protocol

   OWAMP: One-Way Active Measurement Protocol

1.1.2.  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].

2.  TWAMP Extensions

   TWAMP connection establishment follows the procedure defined in
   Section 3.1 of [RFC4656] and Section 3.1 of [RFC5357] where the Modes
   field been used to identify and select specific communication
   capabilities.  At the same time the Modes field been recognized and
   used as extension mechanism [RFC6038].  The new feature requires new
   bit position to identify the ability of a Session-Reflector to return
   value of received DSCP and ECN values back to a Session-Sender, and
   to support the new Session-Reflector packet format in the TWAMP-Test
   protocol.  See the Section 3 for details on the assigned value and
   bit position.

2.1.  Setting Up Connection to Monitor DSCP and ECN

   The Server sets DSCP and ECN Monitoring flag in Modes field of the
   Server Greeting message to indicate its capabilities and willingness
   to monitor them.  If the Control-Client agrees to monitor DSCP and
   ECN on some or all test sessions invoked with this control
   connection, it MUST set the DSCP and ECN Monitoring flag in Modes
   field in the Setup Response message.






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2.2.  TWAMP-Test Extension

   Monitoring of DSCP and ECN requires support by Session-Reflector and
   changes format of its test packet format both in unauthenticated,
   authenticated and encrypted modes.  Monitoring of DSCP and ECN does
   not alter Session-Sender test packet format but certain
   considerations must be taken when and if this mode is accepted in
   combination with Symmetrical Size mode[RFC6038].

2.2.1.  Session-Reflector Packet Format for DSCP and ECN Monitoring

   When Session-Reflector supports DSCP and ECN Monitoring it MUST
   construct Sender DSCP and ECN (S-DSCP-ECN) field for each test packet
   it sends to Session-Sender according to the following procedure:

      - first six bits MUST be copied Differentiated Service field from
      received Session-Sender test packet into Sender DSCP (S-DSCP)
      field;

      - following two bits MUST be copied ECN field from received
      Session-Sender test packet into Sender ECN (S-ECN) field.


    0     1     2     3     4     5     6     7     8
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |               S-DSCP              |   S-ECN   |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                Figure 1: Sender DSCP and ECN field format

   For unauthenticated mode:




















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    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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                  Sequence Number                            |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                          Timestamp                          |
    |                                                             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |       Error Estimate        |             MBZ               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                     Receive Timestamp                       |
    |                                                             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                  Sender Sequence Number                     |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                     Sender Timestamp                        |
    |                                                             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |    Sender Error Estimate    |             MBZ               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | Sender TTL  |  S-DSCP-ECN   |             MBZ               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                                                             |
    +                                                             +
    |                                                             |
    .                                                             .
    .                        Packet Padding                       .
    |                                                             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     Figure 2: Session-Reflector test packet format with DSCP and ECN
                    monitoring in unauthenticated mode

   For authenticated and encrypted modes:

    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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                    Sequence Number                          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                                                             |
    |                     MBZ (12 octets)                         |
    |                                                             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                       Timestamp                             |
    |                                                             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |       Error Estimate        |                               |



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    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
    |                        MBZ (6 octets)                       |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                      Receive Timestamp                      |
    |                                                             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                       MBZ (8 octets)                        |
    |                                                             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                   Sender Sequence Number                    |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                                                             |
    |                      MBZ (12 octets)                        |
    |                                                             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                      Sender Timestamp                       |
    |                                                             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |    Sender Error Estimate    |                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
    |                       MBZ (6 octets)                        |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | Sender TTL  |  S-DSCP-ECN   |                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
    |                                                             |
    +                                                             +
    |                       MBZ (14 octets)                       |
    |                                                             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                                                             |
    |                      HMAC (16 octets)                       |
    |                                                             |
    |                                                             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                                                             |
    .                                                             .
    .                   Packet Padding                            .
    |                                                             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     Figure 3: Session-Reflector test packet format with DSCP and ECN
              monitoring in authenticated or encrypted modes

   The DSCP value is often copied into reflected test packets with
   current TWAMP implementations (with or without TWAMP-Control
   protocol).  With DSCP and ECN Monitoring Extenstion Session-Reflector
   handles DSCP as following:




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      The Session-Reflector MUST extracts the S-DSCP-ECN value from the
      DSCP and ECN values of received packets;

      The Session-Reflector MUST transmit each reflected test packet
      with DSCP set to the negotiated/provisioned value;

      If the negotiated/provisioned DSCP value is not known (e.g.  TWAMP
      Light), the choice of the DSCP is implementation specific.  For
      instance, Session-Reflector MAY copy the DSCP value from the
      received test packet and set it as DSCP in a reflected packet.

2.2.2.  DSCP and ECN Monitoring with RFC 6038 extensions

   [RFC6038] defined two extensions to TWAMP.  First, to ensure that
   Session-Sender and Session-Reflector exchange TWAMP-Test packets of
   equal size.  Second, to specify number of octets to be reflected by
   Session-Reflector.  If DSCP and ECN monitoring and Symmetrical Size
   and/or Reflects Octets modes being negotiated between Server and
   Control-Client in Unauthenticated mode, then because Sender DSCP and
   Sender ECN increase size of unauthenticated Session-Reflector packet
   by 4 octets the Padding Length value SHOULD be >= 28 octets to allow
   for the truncation process that TWAMP recommends in Section 4.2. 1 of
   [RFC5357].

    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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                    Sequence Number                          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                          Timestamp                          |
    |                                                             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |       Error Estimate        |                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
    |                                                             |
    |                       MBZ (28 octets)                       |
    |                                                             |
    +                             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                             |                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
    |                                                             |
    .                                                             .
    .                        Packet Padding                       .
    |                                                             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       Figure 4: Session-Sender test packet format with DSCP and ECN
      monitoring and Symmetrical Test Packet in unauthenticated mode



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2.2.3.  Consideration for TWAMP Light mode

   Appendix I of [RFC5357] does not explicitly state how value of Type-P
   descriptor synchronized between Session-Sender and Session-Reflector
   and whether different values considered as error condition and should
   be reported.  We assume that by some means Session-Sender and
   Session-Reflector of given TWAMP-Test session informed to use the
   same DSCP value.  Same means, i.e. configuration, could be used to
   inform Session-Reflector to support DSCP and ECN monitoring mode by
   copying data from received TWAMP test packets.  Then Session-Sender
   may be informed to use Sender DSCP and ECN field in reflected TWAMP
   test packet.

3.  IANA Considerations

   The TWAMP-Modes registry defined in [RFC5618].

   IANA is requested to reserve a new DSCP and ECN Monitoring Capability
   as follows:

   +------------+--------------------+---------------------+-----------+
   | Value      | Description        | Semantics           | Reference |
   +------------+--------------------+---------------------+-----------+
   | X          | DSCP and ECN       | bit position Y      | This      |
   | (proposed  | Monitoring         | (proposed 7)        | document  |
   | 128)       | Capability         |                     |           |
   +------------+--------------------+---------------------+-----------+

           Table 1: New Type-P Descriptor Monitoring Capability

4.  Security Considerations

   Monitoring of DSCP and ECN does not appear to introduce any
   additional security threat to hosts that communicate with TWAMP as
   defined in [RFC5357], and existing extensions [RFC6038].  The
   security considerations that apply to any active measurement of live
   networks are relevant here as well.  See the Security Considerations
   sections in [RFC4656] and [RFC5357].

5.  Acknowledgements

   Authors greatly appreciate thorough review and thoughtful comments by
   Chritofer Flinta and Samita Chakrabarti.








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6.  References

6.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2474]  Nichols, K., Blake, S., Baker, F., and D. Black,
              "Definition of the Differentiated Services Field (DS
              Field) in the IPv4 and IPv6 Headers", RFC 2474, December
              1998.

   [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.

   [RFC5618]  Morton, A. and K. Hedayat, "Mixed Security Mode for the
              Two-Way Active Measurement Protocol (TWAMP)", RFC 5618,
              August 2009.

   [RFC6038]  Morton, A. and L. Ciavattone, "Two-Way Active Measurement
              Protocol (TWAMP) Reflect Octets and Symmetrical Size
              Features", RFC 6038, October 2010.

6.2.  Informative References

   [RFC2629]  Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629,
              June 1999.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              May 2008.

Authors' Addresses

   Jonas Hedin
   Ericsson

   Email: jonas.hedin@ericsson.com








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   Greg Mirsky
   Ericsson

   Email: gregory.mirsky@ericsson.com


   Steve  Baillargeon
   Ericsson

   Email: steve.baillargeon@ericsson.com









































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