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Versions: 00 draft-ietf-insipid-logme-marking

Internet Engineering Task Force                                 P. Dawes
Internet-Draft                                            Vodafone Group
Intended status: Standards Track                           July 21, 2014
Expires: January 22, 2015


                   Marking SIP Messages to be Logged
                  draft-dawes-insipid-logme-marking-00

Abstract

   SIP networks use signalling monitoring tools to diagnose user
   reported problems and for regression testing if network or user agent
   software is upgraded.  As networks grow and become interconnected,
   including connection via transit networks, it becomes impractical to
   predict the path that SIP signalling will take between user agents,
   and therefore impractical to monitor SIP signalling end-to-end.

   This document describes an indicator for the SIP protocol which can
   be used to mark signalling as of interest to logging.  Such marking
   will typically be applied as part of network testing controlled by
   the network operator and not used in regular user agent signalling.
   However, such marking can be carried end-to-end including the SIP
   user agents, even if a session originates and terminates in different
   networks.

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 http://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 January 22, 2015.

Copyright Notice

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




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   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
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   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.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   3.  Motivating Scenario . . . . . . . . . . . . . . . . . . . . .   3
   4.  Skeleton Diagnostic Procedure . . . . . . . . . . . . . . . .   4
   5.  Protocol for Log-Me Marking . . . . . . . . . . . . . . . . .   5
     5.1.  Configuration for Log-Me Marking  . . . . . . . . . . . .   5
     5.2.  Starting and Stopping Log-Me Marking  . . . . . . . . . .   5
     5.3.  End Points of Log-Me Marking  . . . . . . . . . . . . . .   6
       5.3.1.  Originating and Terminating User Agent  . . . . . . .   6
       5.3.2.  Originating Edge Proxy and Terminating Edge Proxy . .   7
     5.4.  Maintaining State . . . . . . . . . . . . . . . . . . . .   7
     5.5.  Missing Log-me Marker in Dialog Being Logged  . . . . . .   9
     5.6.  Logging Multiple Simultaneous Dialogs . . . . . . . . . .  10
     5.7.  Forked Requests and Back to Back User Agents  . . . . . .  10
       5.7.1.  Propagating the Log-me Marker in Forked Requests  . .  10
       5.7.2.  B2BUA Processing of Log-Me Marker . . . . . . . . . .  10
     5.8.  'Log-Me' Marker . . . . . . . . . . . . . . . . . . . . .  10
       5.8.1.  Header Field Parameter for Session-ID . . . . . . . .  10
       5.8.2.  Identifying Test Cases  . . . . . . . . . . . . . . .  11
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
     6.1.  Trust Domain  . . . . . . . . . . . . . . . . . . . . . .  11
     6.2.  Security Threats  . . . . . . . . . . . . . . . . . . . .  11
       6.2.1.  The Log-Me Marker . . . . . . . . . . . . . . . . . .  11
       6.2.2.  Activating Debug  . . . . . . . . . . . . . . . . . .  11
     6.3.  Protecting Logs . . . . . . . . . . . . . . . . . . . . .  12
   7.  Augmented BNF for the "debug" Parameter . . . . . . . . . . .  12
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  12
     8.1.  Registration of the "debug" Parameter . . . . . . . . . .  12
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  12
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  12
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  13
   Appendix A.  Additional Stuff . . . . . . . . . . . . . . . . . .  13
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  13






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1.  Introduction

   If users experience problems with setting up sessions using SIP,
   their service provider needs to find out why by examining the SIP
   signalling.  Also, if network or user agent software or hardware is
   upgraded regression testing is needed.  Such diagnostics apply to a
   small proportion of network traffic and can apply end-to-end, even if
   signalling crosses several networks possibly belonging to several
   different network operators.  It may not be possible to predict the
   path through those networks in advance, therefore a mechanism is
   needed to mark a session as being of interest so that SIP entities
   along the signalling path can provide diagnostic logging.  This
   document describes a solution that meets the requirements for such a
   'log me' marker for SIP signalling as defined in draft-insipid-logme-
   reqs [I-D.dawes-insipid-logme-reqs].

2.  Requirements Language

   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.  Motivating Scenario

   Signalling for SIP session setup can cross several networks, and
   these networks may not have common ownership and also may be in
   differrent countries.  If a single operator wishes to perform
   regression testing or fault diagnosis end-to-end, the separate
   ownership of networks that carry the signalling and the explosion in
   the number of possible signalling paths through SIP entities from the
   originating to the terminating user make it impractical to pre-
   configure logging of an end-to-end SIP signalling of a session of
   interest.

   The figure below shows an example of a signalling path through
   multiple networks.















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      +------------------+          +------------------+
      | COUNTRY A        |          | COUNTRY B        |
      | Operator A       |          | Operator A       |
      |                  |          |                  |
      | SIP Phones       |          | SIP Phones       |
      |                  |        //|                  |
      +------------------+       // +------------------+
             |                  //
             |                 //
          ,'```',             //    +------------------+
      .`',.'        `..'``',<==//     | COUNTRY B        |
      ,'  Operator A         `',        | Operator A       |
      ;    Backbone Network    ..'-------|                  |
      ',            ,.,    .'`          | PSTN phones      |
      '.,.`'.,,,.`   `''`             |                  |
             ||                     +------------------+
             ||
             \/
      +------------------+
      |                  |
      |  Transit Network |
      |                  |
      |                  |\\
      +------------------+ \\
              |             \\
              |              \\
      +------------------+    \\    +------------------+
      | COUNTRY D        |     \\   | COUNTRY C        |
      | Operator C       |      \\=>| Operator B       |
      |                  |          |                  |
      | SIP Phones       |          | SIP Phones       |
      |                  |          |                  |
      +------------------+          +------------------+


        Figure 1: Example signalling path through multiple networks

4.  Skeleton Diagnostic Procedure

   The skeleton diagnostic procedure is as follows:

   o  The user's user agent is placed in debug mode.  The user agent
      logs its own signalling and inserts a log me marker into SIP
      requests for session setup

   o  All SIP entities that the signalling traverses, from the first
      proxy the user agent connects to at the edge of the network to the
      destination user agent, can detect that the log me marker is



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      present and can log SIP requests and responses that contain the
      marker if configured to do so.

   o  Subsequent responses and requests in the same dialog are logged.

   o  Logging stops, either because the dialog has ended or because a
      'stop event', typically expiry of a certain amount of time,
      occurred

   o  The user's user agent and any other SIP entity that has logged
      signalling sends logs to a server that is co-ordinating
      diagnostics.

5.  Protocol for Log-Me Marking

   This clause describes the protocol solution to the log-me
   requirements described in draft-dawes-insipid-logme-reqs
   [I-D.dawes-insipid-logme-reqs].

5.1.  Configuration for Log-Me Marking

   Configuration of a user agent or proxy to perform log-me marking can
   be done in any way that is convenient to the configured entity.  For
   example, an XML file might be used to list conditions for starting
   and stopping based on time.

               <start>09:00:00</start>
               <stop>09:10:00</stop>

               Figure 2: Simple example log-me configuration

   Logging is on a per-dialog basis and individual logs are
   differentiated by their test identifier, which is defined in
   Section 5.8.2 of this document.  Therefore, an individual log for an
   individual dialog is closed when that dialog ends.  Logging is
   typically done separately from regualar operation, which means that
   tests can be designed to be short enough to troubleshoot quickly and
   to limit the size of individual logs.  If logging is configured so
   that everything is logged for a specified number of minutes then
   several separate dialogs might start and finish meaning that several
   logs may be generated, each one distinguished by its test identifier.

5.2.  Starting and Stopping Log-Me Marking

   A proxy or user agent needs to determine when it needs to log-me mark
   a SIP request or response.  A user agent or proxy log-me marks a
   request or response for two reasons: either it is configured to do so
   or it has detected that a dialog is being log-me marked and maintains



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   state to ensure that all requests and responses in the dialog are
   log-me marked.  A regression test might be configured to log-me mark
   all SIP dialogs created during a given time period whereas a
   troubleshooting test might be configured to mark a dialog based on
   criteria specific to a reported fault.  When configuration has caused
   a user agent or proxy to start log-me marking requests and responses,
   marking continues until the dialog ends.

5.3.  End Points of Log-Me Marking

   Log-me marking is initiated on a dialog creating side controlled by
   configuration.  The dialog terminating side detects an incoming log-
   me marker and reacts accordingly.

5.3.1.  Originating and Terminating User Agent

   In the simplest case, an originating user agent will insert a log-me
   marker in the dialog-creating SIP request and all subsequent SIP
   requests within that dialog.  The log-me marker is carried to the
   terminating user agent and the terminating user agent echoes the log-
   me marker in responses.  If the terminating user agent sends an in-
   dialog request on a dialog that is being log-me marked, it inserts a
   log-me marker and the originating user agent echoes the log-me marker
   in responses.  This basic case suggests the following principles:

   o  The originating user agent is configured for debug

   o  The terminating user agent is not configured for debug and cannot
      initiate log-me marking.

   o  The originating user agent logs its own signalling and inserts a
      log me marker into the dialog-creating SIP request and subsequent
      in-dialog SIP requests.

   o  The terminating user agent can detect that a dialog is of interest
      to logging by the existence of a log-me marker in an incoming
      dialog-creating SIP request.

   o  The terminating user agent MUST echo a log-me marker in responses
      to a SIP request that included a log-me marker.

   o  If the terminating user agent has detected that a dialog is being
      log-me marked, it inserts a log-me marker in any in-dialog SIP
      requests that it sends.







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5.3.2.  Originating Edge Proxy and Terminating Edge Proxy

   Some user agents might not support log-me marking.  In order to test
   sessions involving such user agents, the log-me marker is inserted by
   edge proxies on the originating and terminating sides.  The log-me
   marker is carried to the terminating user agent but the terminating
   user agent is not able to echo the log-me marker in responses to that
   request.  Therefore the terminating edge proxy inserts a log-me
   marker in reponses to the request.  Likewise, if the terminating user
   agent sends an in-dialog request, the terminating edge proxy inserts
   a log-me marker and the originating edge proxy echoes the log-me
   marker in responses to that request.  This case suggests the
   following principles:

   o  The originating edge proxy is configured for debug.

   o  The terminating edge proxy is not configured for debug and cannot
      initiate log-me marking.

   o  The originating edge proxy logs its own signalling and inserts a
      log me marker into SIP requests for session setup.

   o  The terminating edge proxy can detect that a dialog is of interest
      to logging by the existence of a log-me marker in an incoming SIP
      request.

   o  The terminating edge proxy MUST echo a log-me marker in responses
      to a SIP request that included a log-me marker.

   o  If the terminating edge proxy has detected that a dialog is being
      log-me marked, it inserts a log-me marker in in-dialog SIP
      requests from the terminating user agent.

   o  The originating edge proxy echoes the log-me marker in responses
      to in-dialog requests received from the terminating side.

5.4.  Maintaining State

   If a proxy inserts a log-me marker in a SIP request (because a user
   agent did not) then it must ensure that a log-me marker is also
   inserted in responses to that request.  A proxy on the terminating
   side that receives a SIP reqeust with a log-me marker may also ensure
   that responses to that requset contain a log-me marker by inserting
   one if the terminating user agent did not.  Entities that perform
   this log-me marking or checking must maintain a record of which
   dialogs are being log-me marked.





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   In the figure below, the edge proxy in the originating network
   maintains state to ensure log-me marking of SIP requests and in the
   terminating network the registrar maintains state to ensure log-me
   marking of SIP responses.  Such behaviour is useful for logging if
   end devices do not insert or echo a log-me marker.


         Alice           Proxy           Registrar
         u1.foocorp.com  p1.foocorp.com  r1.foocorp.com
         |                  |                  |
         |(1) INVITE        |                  |
         |    (u1 does not insert log-me marker in SIP request)
         |----------------->|                  |
         |                  |(2) INVITE        |
         |                  |    'log-me' marker
         |                  |    (p1 inserts log-me marker. p1 maintains
         |                  |     state and inserts log-me marker in all
         |                  |     requests on this dialog)
         |                  |----------------->|
         |                  |                  |(3) INVITE
         |                  |                  | 'log-me' marker
         |                  |                  |--------> (to barcorp)
         |                  |                  |
         |                  |                  |
         |                  |                  |
         |                  |                  |(8) 200 OK
         |                  |                  | 'log-me' marker
         |                  |(9) 200 OK        |<-------- (from barcorp)
         |                  |    'log-me' marker
         |                  |<-----------------|
         |(10) 200 OK       |                  |
         |    'log-me' marker                  |
         |<-----------------|                  |
         |                  |                  |
         |(11) ACK          |                  |
         |--------------------------------------------------------->
         |                  |                  |


            Proxy           Registrar       Bob
            p1.barcorp.com  r1.barcorp.com  u1.barcorp.com
               |                  |                  |
         (3) INVITE               |                  |
          'log-me' marker         |                  |
         ----->|(from foocorp)    |                  |
               |                  |                  |
               |(4) INVITE        |                  |
               |    'log-me' marker                  |



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               |----------------->|                  |
               |                  |(r1 detects that this dialog is
               |                  | being log-me marked)
               |                  |                  |
               |                  |                  |
               |                  |(5) INVITE        |
                                  |    'log-me' marker
               |                  |----------------->|
               |                  |                  |
               |                  |(6) 200 OK        |
               |                  | (u1 does not echo LogMe:
               |                  |  to SIP response)|
               |                  |<-----------------|
               |(7) 200 OK        |                  |
               |'log-me' marker   |                  |
               |    (r1 inserts log-me marker. r1 maintains
               |     state and inserts log-me marker in all
               |     responses on this dialog)
               |<-----------------|                  |
               |                  |                  |
          (8) 200 OK              |                  |
              'log-me' marker     |                  |
          <----|                  |                  |
               |                  |                  |
          (11) ACK                |                  |
           from foocorp)  -------------------------->|
               |                  |                  |
               |                  |                  |
               |                  |(12) re-INVITE    |
               |                  |<-----------------|
               |                  |(in-dialog request)
               |                  |                  |
               |(13) re-INVITE    |                  |
               |'log-me' marker   |                  |
               |<-----------------|                  |
               |(r1 inserts log-me marker into in-dialog
               | requests sent from the terminating user agent)
               |                  |                  |


              Figure 3: Maintaining state for log-me marking

5.5.  Missing Log-me Marker in Dialog Being Logged

   A terminating user agent or terminating edge proxy that has been
   echoing markers in responses for a given dialog might receive a SIP
   request that has not been log-me marked.  Since log-me marking is
   done per dialog, this is an error.  In such cases, the proxy SHOULD



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   consider log-me marking to have ended and MUST NOT mark a response to
   the unmarked request, responses to subsequent requests in the dialog,
   or in-dialog requests sent from the terminating side.  Similarly,
   log-me marking that begins mid-dialog is an error case and the
   terminating user agent or edge proxy MUST NOT log-me mark responses
   to the marked request, responses to subsequent requests in the
   dialog, or in-dialog requests from the terminating side.

5.6.  Logging Multiple Simultaneous Dialogs

   An originating or terminating user agent and SIP entities on the
   signaling path can log multiple SIP dialogs simultaneously, these
   dialogs are differentiated by their test identifier.

5.7.  Forked Requests and Back to Back User Agents

5.7.1.  Propagating the Log-me Marker in Forked Requests

   Log-me marking is copied into forked requests.

5.7.2.  B2BUA Processing of Log-Me Marker

   A B2BUA SHOULD act on the terminating side as described for a
   terminating user agent and therefore log marked incoming requests,
   echo log-me marking in responses to log-me marked requests, and log-
   me mark in-dialog SIP requests that it sends if the dialog is being
   log-me marked.

   A B2BUA SHOULD act on the originating side as described for an
   originating user agent and therefore mark SIP requests if and only if
   configured to do so, and echo log-me marking in responses to in-
   dialog requests received from the terminating side.

5.8.  'Log-Me' Marker

5.8.1.  Header Field Parameter for Session-ID

   A new header field parameter called debug is defined to be used with
   the Session-ID header field (described in draft-ietf-insipid-session-
   id [I-D.ietf-insipid-session-id]).











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            Alice           Proxy           Registrar          Debug Server
            u1.foocorp.com  p1.foocorp.com  r1.foocorp.com     d1.foocorp.com
            |                  |                  |                  |
            |(1) INVITE        |                  |                  |
            | Session-ID: ab30317f1a784dc48ff824d0d3715d86;          |
            |               remote=47755a9de7794ba387653f2099600ef2; debug
            |----------------->|                  |                  |
            |                  |                  |                  |


    Figure 4: Log-me marking using the "debug" Session-ID: header field
                                 parameter

5.8.2.  Identifying Test Cases

   The test case identifier is the Session-ID in the Session-ID header
   field (described in draft-ietf-insipid-session-id
   [I-D.ietf-insipid-session-id]).  A log relates to exactly one dialog
   and logs are distinguished by their test case identifier.

6.  Security Considerations

6.1.  Trust Domain

   Since a log me marker may cause a SIP entity to log the SIP header
   and body of a request or response, the log me marker SHOULD be
   removed at a trust domain boundary.  If a prior agreement to log
   sessions exists with the net hop network then the log me marker might
   not be removed.

6.2.  Security Threats

6.2.1.  The Log-Me Marker

   The log me marker is not sensitive information, although it will
   sometimes be inserted because a particular device is experiencing
   problems.

   The presence of a log me marker will cause some SIP entities to log
   signalling.  Therefore, this marker MUST be removed at the earliest
   opportunity if it has been incorrectly inserted.

6.2.2.  Activating Debug

   Activating a debug mode affects the operation of a user agent,
   therefore it MUST be supplied by an authorized server to an
   authorized user agent, it MUST NOT be altered in transit, and it MUST
   NOT be readable by an unauthorized third party.



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6.3.  Protecting Logs

   A SIP entity that has logged information SHOULD encrypt it, such that
   it can be decrypted only by a person authorized to examine the logged
   information.

7.  Augmented BNF for the "debug" Parameter

   ABNF is described in RFC 5234 [RFC5234]

   debug-param = "debug"

8.  IANA Considerations

8.1.  Registration of the "debug" Parameter

   The following parameter is to be added to the "Header Field
   Parameters and Parameter Values" section of the SIP parameter
   registry:

     +--------------+----------------+-------------------+-----------+
     | Header Field | Parameter Name | Predefined Values | Reference |
     +--------------+----------------+-------------------+-----------+
     | Session-ID   | debug          | No                | [RFCXXXX] |
     +--------------+----------------+-------------------+-----------+

                                  Table 1

9.  References

9.1.  Normative References

   [I-D.dawes-insipid-logme-reqs]
              Dawes, P., "Requirements for Marking SIP Messages to be
              Logged", draft-dawes-insipid-logme-reqs-00 (work in
              progress), January 2014.

   [I-D.ietf-insipid-session-id]
              Jones, P., Pearce, C., Polk, J., and G. Salgueiro, "End-
              to-End Session Identification in IP-Based Multimedia
              Communication Networks", draft-ietf-insipid-session-id-06
              (work in progress), April 2014.

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






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9.2.  Informative References

   [RFC5234]  Crocker, D. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234, January 2008.

Appendix A.  Additional Stuff

   This becomes an Appendix.

Author's Address

   Peter Dawes
   Vodafone Group
   The Connection
   Newbury, Berkshire  RG14 2FN
   UK

   Email: peter.dawes@vodafone.com

































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