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

Versions: (draft-sandbakken-xcon-bfcp-udp) 00 01 02 03 draft-ietf-bfcpbis-rfc4582bis

Dispatch Working Group                                     T. Kristensen
Internet-Draft                                               M. Thompson
Updates: 4582, 4583                                        G. Sandbakken
(if approved)                                                T. Andersen
Intended status: Standards Track                               E. McLeod
Expires: April 28, 2011                                            Cisco
                                                        October 25, 2010


  Revision of the Binary Floor Control Protocol (BFCP) for use over an
                          unreliable transport
                 draft-sandbakken-dispatch-bfcp-udp-01

Abstract

   This memo extends the Binary Floor Control Protocol (BFCP) for use
   over an unreliable transport.  It details a set of revisions to the
   protocol definition document and the specification of Session
   Description Protocol (SDP) format for BFCP streams.

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 28, 2011.

Copyright Notice

   Copyright (c) 2010 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



Kristensen, et al.       Expires April 28, 2011                 [Page 1]


Internet-Draft               BFCP-Unreliable                October 2010


   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 . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Revision of RFC4582  . . . . . . . . . . . . . . . . . . . . .  5
     3.1.  Overview of Operation (4)  . . . . . . . . . . . . . . . .  5
     3.2.  Floor Participant to Floor Control Server Interface
           (4.1)  . . . . . . . . . . . . . . . . . . . . . . . . . .  5
     3.3.  COMMON-HEADER Format (5.1) . . . . . . . . . . . . . . . .  5
     3.4.  ERROR-CODE (5.2.6) . . . . . . . . . . . . . . . . . . . .  6
     3.5.  FloorRequestStatusAck (5.3.14) . . . . . . . . . . . . . .  7
     3.6.  ErrorAck (5.3.15)  . . . . . . . . . . . . . . . . . . . .  7
     3.7.  FloorStatusAck (5.3.16)  . . . . . . . . . . . . . . . . .  7
     3.8.  Goodbye (5.3.17) . . . . . . . . . . . . . . . . . . . . .  8
     3.9.  GoodbyeAck (5.3.18)  . . . . . . . . . . . . . . . . . . .  8
     3.10. Transport (6)  . . . . . . . . . . . . . . . . . . . . . .  8
     3.11. Reliable Transport (6.1) . . . . . . . . . . . . . . . . .  9
     3.12. Unreliable Transport (6.2) . . . . . . . . . . . . . . . . 10
     3.13. Lower-Layer Security (7) . . . . . . . . . . . . . . . . . 12
     3.14. Protocol Transactions (8)  . . . . . . . . . . . . . . . . 12
     3.15. Server Behavior (8.2)  . . . . . . . . . . . . . . . . . . 12
     3.16. Timers (8.3) . . . . . . . . . . . . . . . . . . . . . . . 12
     3.17. Request Retransmission Timer, T1 (8.3.1) . . . . . . . . . 13
     3.18. Response Retransmission Timer, T2 (8.3.2)  . . . . . . . . 13
     3.19. Timer Values (8.3.3) . . . . . . . . . . . . . . . . . . . 13
     3.20. Receiving a Response [to a FloorRequest Message]
           (10.1.2) . . . . . . . . . . . . . . . . . . . . . . . . . 14
     3.21. Receiving a Response [to a FloorRelease Message]
           (10.2.2) . . . . . . . . . . . . . . . . . . . . . . . . . 14
     3.22. Receiving a Response [to a ChairAction Message] (11.2) . . 14
     3.23. Receiving a Response [to a FloorQuery Message] (12.1.2)  . 14
     3.24. Receiving a Response [to a FloorRequestQuery Message]
           (12.2.2) . . . . . . . . . . . . . . . . . . . . . . . . . 14
     3.25. Receiving a Response [to a UserQuery Message] (12.3.2) . . 15
     3.26. Receiving a Response [to a Hello Message] (12.4.2) . . . . 15
     3.27. Reception of a FloorRequestStatus Message (13.1.3) . . . . 15
     3.28. Reception of a FloorStatus Message (13.5.3)  . . . . . . . 15
     3.29. Reception of an Error Message (13.8.1) . . . . . . . . . . 15
     3.30. Security Considerations (14) . . . . . . . . . . . . . . . 16
     3.31. IANA Considerations - Primitive Subregistry (15.2) . . . . 16
     3.32. IANA Considerations - Error Code Subregistry (15.4)  . . . 16
     3.33. Example Call Flows for BFCP over Unreliable Transport
           (Appendix A) . . . . . . . . . . . . . . . . . . . . . . . 17



Kristensen, et al.       Expires April 28, 2011                 [Page 2]


Internet-Draft               BFCP-Unreliable                October 2010


   4.  Revision of RFC4583  . . . . . . . . . . . . . . . . . . . . . 20
     4.1.  Fields in the 'm' Line (3) . . . . . . . . . . . . . . . . 20
     4.2.  Security Considerations (10) . . . . . . . . . . . . . . . 21
     4.3.  Registration of SDP 'proto' Values (11.1)  . . . . . . . . 21
   5.  Future Work  . . . . . . . . . . . . . . . . . . . . . . . . . 21
   6.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 22
   7.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 22
     7.1.  Normative References . . . . . . . . . . . . . . . . . . . 22
     7.2.  Informative References . . . . . . . . . . . . . . . . . . 23
   Appendix A.  Change History  . . . . . . . . . . . . . . . . . . . 23
     A.1.  draft-sandbakken-dispatch-bfcp-udp-00 to -01 . . . . . . . 23
     A.2.  draft-sandbakken-xcon-bfcp-udp-02 to
           draft-sandbakken-dispatch-bfcp-udp-00  . . . . . . . . . . 24
     A.3.  draft-sandbakken-xcon-bfcp-udp-01 to -02 . . . . . . . . . 24
     A.4.  draft-sandbakken-xcon-bfcp-udp-00 to -01 . . . . . . . . . 25
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 25



































Kristensen, et al.       Expires April 28, 2011                 [Page 3]


Internet-Draft               BFCP-Unreliable                October 2010


1.  Introduction

   The motivation for using an unreliable transport for BFCP [RFC4582]
   messages is fuelled by network deployments where RTP proxies or media
   relays are present for NAT and firewall traversal.  In these
   deployments, TCP may neither be applicable nor appropriate, for
   example, due to lack of support for TCP media relay, ICE-TCP
   [I-D.ietf-mmusic-ice-tcp] or a standard UDP tunneling approach.

   This draft extends the BFCP protocol to support unreliable transport.
   Minor changes to the transaction model are introduced in that all
   requests now have an appropriate response to complete the
   transaction.  The requests are sent with a retransmit timer
   associated with the response to achieve reliability.

   The intention is not to change the semantics of BFCP, but to present
   a trivial and workable extension that permits UDP as a transport.
   Existing implementations in the spirit of the approach detailed in
   earlier versions of this draft (cf. Appendix A), have demonstrated
   the approach to be feasible.  The purpose of this document is to
   formalize the deviations from the baseline specification enabling
   interoperability between implementations.

   The content of this draft relates to the BFCP protocol specification
   [RFC4582] and the SDP format for describing BFCP streams [RFC4583].
   This draft is written with the goal of being incorporated into an
   upcoming revisions of those documents without requiring additional
   protocol and stream specification documents.  These two future bis
   drafts will also deal with known issues and erratas not related to
   the extensions described in this draft.

   Earlier versions of this draft was submitted to the XCON working
   group.  As XCON is closing the draft is now moved and associated with
   the Dispatch working group.  The draft is in progress and notable
   remaining work is detailed in Section 5.


2.  Terminology

   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 [RFC2119].

   RFC-editor note: RFC XXXX and RFC YYYY are to be replaced by the RFC
   numbers the two -bis specifications (RFC4582bis and RFC4583bis),
   spawning from this draft, recieves when published.





Kristensen, et al.       Expires April 28, 2011                 [Page 4]


Internet-Draft               BFCP-Unreliable                October 2010


3.  Revision of RFC4582

   This section details revisions to [RFC4582], the base protocol
   specification of BFCP.  The section number to which updates apply are
   indicated in parentheses in the titles of the sub-sections below.

3.1.  Overview of Operation (4)

   Fourth paragraph change:

      There are two types of transaction in BFCP: client-initiated
      transactions and server-initiated transactions.  Client-initiated
      transactions consist of a message from a client to the floor
      control server and a response from the floor control server to the
      client.  Correspondingly, server-initiated transactions consist of
      a message from the floor control server to a client and the
      associated acknowledgement message from the client to the floor
      control server.  Both messages can be related because they carry
      the same Transaction ID value in their common headers.

3.2.  Floor Participant to Floor Control Server Interface (4.1)

   Before seventh paragraph (page 9), insert:

      Figures 2 and 3 below show call flows for two sample BFCP
      interactions when used over reliable transport.  Appendix A
      (Editorial Note: here-in Section 3.33) shows the same sample
      interactions but over an unreliable transport.

3.3.  COMMON-HEADER Format (5.1)

   The figure below should replace Figure 5: COMMON-HEADER format.


     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | Ver |I|  Res  |  Primitive    |        Payload Length         |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                         Conference ID                         |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Transaction ID        |            User ID            |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                      Figure 1: COMMON-HEADER format

   The following text preceeds "Reserved" on page 15:




Kristensen, et al.       Expires April 28, 2011                 [Page 5]


Internet-Draft               BFCP-Unreliable                October 2010


      I: The Transaction Initiator (I) flag-bit has relevance only for
      use of BFCP over unreliable media.  When clear, it signifies that
      the transaction was opened by the client (floor participant,
      chair) and that the Transaction ID that follows has been generated
      by the client; when set, the transaction is a server-initiated
      transaction and the Transaction ID that follows is pertinent to
      the floor control server.  Where BFCP is used over reliable
      transports, the flag has no significance and SHOULD be cleared.

   The Reserved field changes name to Res due to limited space in the
   ASCII graphic in Figure 1.  In the description of the Reserved field
   "the 5 bits" is changed to "the 4 bits".

   The description of Transaction ID should have the final clause
   deleted with the reference to Section 8 remaining.  The value used
   for server-initiated transactions shall be non-zero when BFCP is used
   over unreliable transports, and this qualification shall be described
   in the updated Section 8.

   The values below should be appended to the end of Table 1: BFCP
   primitives.

          +-------+-----------------------+--------------------+
          | Value | Primitive             | Direction          |
          +-------+-----------------------+--------------------+
          |   14  | FloorRequestStatusAck | P -> S ; Ch -> S   |
          |   15  | ErrorAck              | P -> S ; Ch -> S   |
          |   16  | FloorStatusAck        | P -> S ; Ch -> S   |
          |   17  | Goodbye               | P -> S ; Ch -> S ; |
          |       |                       | S -> P ; S  -> Ch  |
          |   18  | GoodbyeAck            | P -> S ; Ch -> S ; |
          |       |                       | S -> P ; S  -> Ch  |
          +-------+-----------------------+--------------------+

                         Table 1: BFCP primitives

3.4.  ERROR-CODE (5.2.6)

   The value below should be appended to the end of Table 5: Error Code
   meaning.

                    +-------+-------------------------+
                    | Value | Meaning                 |
                    +-------+-------------------------+
                    |   10  | Unable to parse message |
                    +-------+-------------------------+

                        Table 2: Error Code meaning



Kristensen, et al.       Expires April 28, 2011                 [Page 6]


Internet-Draft               BFCP-Unreliable                October 2010


3.5.  FloorRequestStatusAck (5.3.14)

   This new subsection should be added to specify the normative ABNF for
   the new primitive, FloorRequestStatusAck.

      Floor participants and chairs acknowledge the receipt of a
      FloorRequestStatus message from the floor control server when
      communicating over unreliable transport.  The following is the
      format of the FloorRequestStatusAck message:



   FloorRequestStatusAck          =    (COMMON-HEADER)
                                      *[EXTENSION-ATTRIBUTE]

                    Figure 2: FloorRequestStatusAck format

3.6.  ErrorAck (5.3.15)

   This new subsection should be added to specify the normative ABNF for
   the new primitive, ErrorAck.

      Floor participants and chairs acknowledge the receipt of an Error
      message from the floor control server when communicating over
      unreliable transport.  The following is the format of the ErrorAck
      message:



   ErrorAck                       =    (COMMON-HEADER)
                                      *[EXTENSION-ATTRIBUTE]

                          Figure 3: ErrorAck format

3.7.  FloorStatusAck (5.3.16)

   This new subsection should be added to specify the normative ABNF for
   the new primitive, FloorStatusAck.

      Floor participants and chairs acknowledge the receipt of a
      FloorStatus message from the floor control server when
      communicating over unreliable transport.  The following is the
      format of the FloorStatusAck message:








Kristensen, et al.       Expires April 28, 2011                 [Page 7]


Internet-Draft               BFCP-Unreliable                October 2010


   FloorStatusAck                 =    (COMMON-HEADER)
                                      *[EXTENSION-ATTRIBUTE]

                       Figure 4: FloorStatusAck format

3.8.  Goodbye (5.3.17)

   This new subsection should be added to specify the normative ABNF for
   the new primitive, Goodbye.

      BFCP entities that wish to dissociate themselves from their remote
      participant do so through the transmission of a Goodbye.  The
      following is the format of the Goodbye message:



   Goodbye                        =    (COMMON-HEADER)
                                      *[EXTENSION-ATTRIBUTE]

                           Figure 5: Goodbye format

3.9.  GoodbyeAck (5.3.18)

   This new subsection should be added to specify the normative ABNF for
   the new primitive, GoodbyeAck.

      BFCP entities communicating over an unreliable transport should
      acknowledge the receipt of a Goodbye message from a peer.  The
      following is the format of the GoodbyeAck message:



   GoodbyeAck                     =    (COMMON-HEADER)
                                      *[EXTENSION-ATTRIBUTE]

                         Figure 6: GoodbyeAck format

3.10.  Transport (6)

   Much of the existing text remains, but is demoted to become
   subsection 6.1.  This draft recommends an additional behavior for
   entities participating in communication over a reliable transport
   that either wish to leave or are asked to leave an established BFCP
   connection, as detailed in the revised section introduction text
   below.






Kristensen, et al.       Expires April 28, 2011                 [Page 8]


Internet-Draft               BFCP-Unreliable                October 2010


      The transport over which BFCP entities exchange messages depends
      on how clients obtain information to contact the floor control
      server (e.g. using an SDP offer/answer exchange [RFC4583]).  Two
      transports are supported: TCP, appropriate where entities can be
      sure that their connectivity is not impeded by NAT devices, media
      relays or firewalls; and UDP for those deployments where TCP may
      not be applicable or appropriate.

      If a client wishes to end its BFCP association with a floor
      control server, it is RECOMMENDED that the client send a Goodbye
      message to dissociate itself from any allocated resources.  If a
      floor control server wishes to end its BFCP association with a
      client (e.g. the Focus of the conference informs the floor control
      server that the client has been kicked out from the conference),
      it is RECOMMENDED that the floor control server send a Goodbye
      message towards the client.

3.11.  Reliable Transport (6.1)

   BFCP entities may elect to exchange BFCP messages using TCP
   connections.  TCP provides an in-order reliable delivery of a stream
   of bytes.  Consequently, message framing is implemented in the
   application layer.  BFCP implements application-layer framing using
   TLV-encoded attributes.

   A client MUST NOT use more than one TCP connection to communicate
   with a given floor control server within a conference.  Nevertheless,
   if the same physical box handles different clients (e.g. a floor
   chair and a floor participant), which are identified by different
   User IDs, a separate connection per client is allowed.

   If a BFCP entity (a client or a floor control server) receives data
   that cannot be parsed, the entity MUST close the TCP connection, and
   the connection SHOULD be reestablished.  Similarly, if a TCP
   connection cannot deliver a BFCP message and times out, the TCP
   connection SHOULD be reestablished.

   The way connection reestablishment is handled depends on how the
   client obtains information to contact the floor control server.  Once
   the TCP connection is reestablished, the client MAY resend those
   messages for which it did not get a response from the floor control
   server.

   If a floor control server detects that the TCP connection towards one
   of the floor participants is lost, it is up to the local policy of
   the floor control server what to do with the pending floor requests
   of the floor participant.  In any case, it is RECOMMENDED that the
   floor control server keep the floor requests (i.e., that it does not



Kristensen, et al.       Expires April 28, 2011                 [Page 9]


Internet-Draft               BFCP-Unreliable                October 2010


   cancel them) while the TCP connection is reestablished.

   To maintain backwards compatibility with older implementations of
   [RFC4583], BFCP entities MUST interpret the graceful close of their
   TCP connection from their associated participant as an implicit
   Goodbye message.

3.12.  Unreliable Transport (6.2)

   BFCP entities may elect to exchange BFCP messages using UDP
   datagrams.  UDP is an unreliable transport where neither delivery nor
   delivery order is assured.  Each BFCP UDP datagram MUST contain only
   one BFCP message.  The message format for exchange of BFCP in UDP
   datagrams is the same as for a TCP stream above.

   Clients MUST announce their presence to the floor control server by
   transmission of a Hello message.  This Hello message MUST be
   responded to with a HelloAck message and only upon receipt can the
   client consider the floor control service as present and available.

   As described in Section 8, each request sent by a floor participant
   or chair shall form a client transaction that expects an
   acknowledgement message back from the floor control server within a
   retransmission window.  Concordantly, messages sent by the floor
   control server that are not transaction-completing (e.g.  FloorStatus
   announcements as part of a FloorQuery subscription) are server-
   initiated transactions that require acknowledgement messages from the
   floor participant and chair entities to which they were sent.

   If a BFCP entity receives data that cannot be parsed, the receiving
   participant MAY send an Error message with parameter value 10
   indicating receipt of a malformed message.  If the message can be
   parsed to the extent that it is able to discern that it was a
   response to an outstanding request transaction, the client MAY
   discard the message and await retransmission.  BFCP entities
   receiving an Error message with value 10 SHOULD acknowledge the error
   and act accordingly.

   Transaction ID values are non-sequential and entities are at liberty
   to select values at random.  Entities MUST only have at most one
   outstanding request transaction at any one time.  Implicit
   subscriptions, such as FloorRequest messages that have multiple
   responses as the floor control server processes intermediate states
   until Granted or Denied terminal states attained, can be
   characterized by a client-initiated request transaction whose
   acknowledgement is implied by the first FloorRequestStatus response
   from the floor control server.  The subsequent changes in state for
   the request are new transactions whose Transaction ID is determined



Kristensen, et al.       Expires April 28, 2011                [Page 10]


Internet-Draft               BFCP-Unreliable                October 2010


   by the floor control server and whose receipt by the client
   participant shall be acknowledged with a FloorRequestStatusAck
   message.

   By restricting entities to having at most one pending transaction
   open, the out-of-order receipt of messages is mitigated.  A server-
   initiated request (e.g. a FloorStatus with an update from the floor
   control server) received by a participant before the initial
   FloorRequestStatus message that closes the client-initiated
   transaction that was instigated by the FloorRequest clearly
   supercedes the information conveyed in the delinquent response.  As
   the floor control server cannot send a second update to the implicit
   floor status subscription until the first is acknowledged, ordinality
   is maintained.

   BFCP may be characterized to generate "low data-volume" traffic,
   after the classification in [RFC5405].  Nevertheless is it necessary
   to ensure suitable and necessary congestion control mechanisms are
   used for BFCP over UDP.  As described in previous paragraph every
   entity - client or server - is only allowed to send one request at a
   time, and await the acknowledging response.  This way at most one
   datagram is sent per RTT given the message is not lost during
   transmission.  In case the message is lost, the request
   retransmission timer T1 specified in Section 3.17 will fire and the
   message is retransmitted up to three times.  The default initial
   interval is set to 500ms and the interval is doubled after each
   retransmission attempt, this is identical to the specification of the
   T1 timer in SIP as described in Section 17.1.1.2 of [RFC3261].

   BFCP entities SHOULD ensure that their messages are smaller than the
   recommended MTU size of 1300 bytes when encoded to minimise
   likelihood of fragmentation en route to their peer entity.

   If a BFCP entity receives an ICMP port unreachable message mid-
   conversation, the entity SHOULD treat the conversation as closed
   (e.g. an implicit Goodbye message from the peer) and behave
   accordingly.  The entity MAY attempt to re-establish the conversation
   afresh.  The new connection will appear as a wholly new floor
   participant, chair or floor control server with all state previously
   held about that participant lost.

   Note: This is because the peer entities cannot rely on IP and port
   tuple to uniquely identify the participant, nor would extending Hello
   to include an attribute that advertised what the entity previously
   was assigned as a User ID be acceptable due to session hijacking.

   In deployments where NAT appliances, firewalls or other such devices
   are present and affecting port reachability for each entity, one



Kristensen, et al.       Expires April 28, 2011                [Page 11]


Internet-Draft               BFCP-Unreliable                October 2010


   possibility is to utilize the peer connectivity checks, relay use and
   NAT pinhole maintenance mechanisms defined in ICE [RFC5245].

3.13.  Lower-Layer Security (7)

   Add the following to the second sentence, change period ('.') with
   comma:

      , if transport over UDP is implemented, DTLS [RFC4347] MUST be
      supported.

   Editorial Note: More details needed, will be dealt with in next
   version of this draft.

3.14.  Protocol Transactions (8)

   The final clause of the introduction to section 8 shall be changed to
   read:

      Since they do not trigger any response, their Transaction ID is
      set to 0 when used over reliable transports, but must be non-zero
      and unique in the context of outstanding transactions over
      unreliable transports.

      When using BFCP over unreliable transports, all requests will use
      retransmit timer T1 (see Section 3.16) until the transaction is
      completed.

3.15.  Server Behavior (8.2)

   The final clause of this section shall be changed to read:

      Server-initiated transactions MUST contain a Transaction ID equal
      to 0 when BFCP is used over reliable transports.  Over unreliable
      transport, the Transaction ID shall have the same properties as
      for client-initiated transactions: the server MUST set the
      Transaction ID value in the common header to a number that is
      different from 0 and that MUST NOT be reused in another message
      from the server until the appropriate response from the client is
      received for the transaction.  The server uses the Transaction ID
      value to match this message with the response from the floor
      participant or floor chair.

3.16.  Timers (8.3)

   New section:





Kristensen, et al.       Expires April 28, 2011                [Page 12]


Internet-Draft               BFCP-Unreliable                October 2010


      When BFCP entities are communicating over an unreliable transport,
      two retransmission timers are employed to help mitigate against
      loss of datagrams.  Retransmission and response caching are not
      required when BFCP entities communicate over reliable transports.

3.17.  Request Retransmission Timer, T1 (8.3.1)

   T1 is a timer that schedules retransmission of a request until an
   appropriate response is received or until the maximum number of
   retransmissions have occurred.  The timer doubles on each re-
   transmit, failing after three unacknowledged transmission attempts.

   If a valid respone is not received for a client- or server-initiated
   transaction, the implementation MUST consider the BFCP association as
   failed.  Implementations SHOULD follow the reestablishment procedure
   described in section 6 (e.g. initiate a new offer/answer [RFC3264]
   exchange).  Alternatively, they MAY continue without BFCP and
   therefore not be participant in any floor control actions.

3.18.  Response Retransmission Timer, T2 (8.3.2)

   T2 is a timer that, when fires, signals that the BFCP entity can
   release knowledge of the transaction against which it is running.  It
   is started upon the first transmission of the response to a request
   and is the only mechanism by which that response is released by the
   BFCP entity.  Any subsequent retransmissions of the same request can
   be responded to by replaying the cached response, whilst that value
   is retained until the timer has fired.

   T2 shall be set such that it encompasses all legal retransmissions
   per T1 plus a factor to accommodate network latency between BFCP
   entities.

3.19.  Timer Values (8.3.3)

   The table below defines the different timers required when BFCP
   entities communicate over an unreliable transport.

        +-------+--------------------------------------+---------+
        | Timer | Description                          | Value/s |
        +-------+--------------------------------------+---------+
        |   T1  | Initial request retransmission timer |   0.5s  |
        |   T2  | Response retransmission timer        |   10s   |
        +-------+--------------------------------------+---------+

                              Table 3: Timers

   The default value for T1 is 500 ms, this is an estimate of the RTT



Kristensen, et al.       Expires April 28, 2011                [Page 13]


Internet-Draft               BFCP-Unreliable                October 2010


   for completing the transaction.  T1 MAY be chosen larger, and this is
   RECOMMENDED if it is known in advance that the RTT is larger.
   Regardless of the value of T1, the exponential backoffs on
   retransmissions described in Section 3.17 MUST be used.

3.20.  Receiving a Response [to a FloorRequest Message] (10.1.2)

   Prepend the sentence below at the start of this subsection:

      When communicating over unreliable transport and upon receiving a
      FloorRequest from a participant, the floor control server MUST
      respond with a FloorRequestStatus message within the transaction
      failure window to complete the transaction.

3.21.  Receiving a Response [to a FloorRelease Message] (10.2.2)

   Prepend the sentence below at the start of this subsection:

      When communicating over unreliable transport and upon receiving a
      FloorRelease from a participant, the floor control server MUST
      respond with a FloorRequestStatus message within the transaction
      failure window to complete the transaction.

3.22.  Receiving a Response [to a ChairAction Message] (11.2)

   Prepend the sentence below at the start of this subsection:

      When communicating over unreliable transport and upon receiving a
      ChairAction from a participant, the floor control server MUST
      respond with a ChairActionAck message within the transaction
      failure window to complete the transaction.

3.23.  Receiving a Response [to a FloorQuery Message] (12.1.2)

   Prepend the sentence below at the start of this subsection:

      When communicating over unreliable transport and upon receiving a
      FloorQuery from a participant, the floor control server MUST
      respond with a FloorStatus message within the transaction failure
      window to complete the transaction.

3.24.  Receiving a Response [to a FloorRequestQuery Message] (12.2.2)

   Prepend the sentence below at the start of this subsection:

      When communicating over unreliable transport and upon receiving a
      FloorRequestQuery from a participant, the floor control server
      MUST respond with a FloorRequestStatus message within the



Kristensen, et al.       Expires April 28, 2011                [Page 14]


Internet-Draft               BFCP-Unreliable                October 2010


      transaction failure window to complete the transaction.

3.25.  Receiving a Response [to a UserQuery Message] (12.3.2)

   Prepend the sentence below at the start of this subsection:

      When communicating over unreliable transport and upon receiving a
      UserQuery from a participant, the floor control server MUST
      respond with a UserStatus message within the transaction failure
      window to complete the transaction.

3.26.  Receiving a Response [to a Hello Message] (12.4.2)

   Prepend the sentence below at the start of this subsection:

      When communicating over unreliable transport and upon receiving a
      Hello from a participant, the floor control server MUST respond
      with a HelloAck message within the transaction failure window to
      complete the transaction.

3.27.  Reception of a FloorRequestStatus Message (13.1.3)

   The sentence below shall appear as a new subsection:

      When communicating over unreliable transport and upon receiving a
      FloorRequestStatus message from a floor control server, the
      participant MUST respond with a FloorRequestStatusAck message
      within the transaction failure window to complete the transaction.

3.28.  Reception of a FloorStatus Message (13.5.3)

   The sentence below shall appear as a new subsection:

      When communicating over unreliable transport and upon receiving a
      FloorStatus message from a floor control server, the participant
      MUST respond with a FloorStatusAck message within the transaction
      failure window to complete the transaction.

3.29.  Reception of an Error Message (13.8.1)

   The sentence below shall appear as a new subsection:

      When communicating over unreliable transport and upon receiving an
      Error message from a floor control server, the participant MUST
      respond with a ErrorAck message within the transaction failure
      window to complete the transaction.





Kristensen, et al.       Expires April 28, 2011                [Page 15]


Internet-Draft               BFCP-Unreliable                October 2010


3.30.  Security Considerations (14)

   It is a requirement that the extension of BFCP for unreliable
   transports shall not introduce any new threats.

   The considerations in [RFC4582] will be altered to cover TCP/TLS
   connections as well as DTLS (UDP/TLS).

   In addition to the RFCs mentioned for TCP and TLS connections, the
   specifications for SRTP over DTLS [RFC5763] and [RFC5764] discuss
   security issues in detail.  Add references to them in the section.

   Editorial Note: Expanded analysis and discussion will be added after
   lower-layer security details is sorted out in Section 3.13.

3.31.  IANA Considerations - Primitive Subregistry (15.2)

   This section instructs the IANA to register the following new values
   for the BFCP primitive subregistry.

               +-------+-----------------------+-----------+
               | Value | Primitive             | Reference |
               +-------+-----------------------+-----------+
               |   14  | FloorRequestStatusAck |  RFC XXXX |
               |   15  | ErrorAck              |  RFC XXXX |
               |   16  | FloorStatusAck        |  RFC XXXX |
               |   17  | Goodbye               |  RFC XXXX |
               |   18  | GoodbyeAck            |  RFC XXXX |
               +-------+-----------------------+-----------+

                    Table 4: BFCP primitive subregistry

3.32.  IANA Considerations - Error Code Subregistry (15.4)

   This section instructs the IANA to register the following new values
   for the BFCP Error Code subregistry.

              +-------+-------------------------+-----------+
              | Value | Meaning                 | Reference |
              +-------+-------------------------+-----------+
              |   10  | Unable to parse message |  RFC XXXX |
              +-------+-------------------------+-----------+

                   Table 5: BFCP Error Code subregistry







Kristensen, et al.       Expires April 28, 2011                [Page 16]


Internet-Draft               BFCP-Unreliable                October 2010


3.33.  Example Call Flows for BFCP over Unreliable Transport (Appendix
       A)

   (Editorial Note: This is a new appendix to [RFC4582].)

   With reference to Section 4.1, the following figures show
   representative call-flows for requesting and releasing a floor, and
   obtaining status information about a floor when BFCP is deployed over
   an unreliable transport.  The figures here show a loss-less
   interaction.

   Editorial Note: A future version of this draft will show an example
   with lost packets due to unreliable transport, as well as examples on
   usage of DTLS and STUN in call the setup phase.


         Floor Participant                                 Floor Control
                                                              Server
                 |(1) FloorRequest                               |
                 |Transaction ID: 123                            |
                 |User ID: 234                                   |
                 |FLOOR-ID: 543                                  |
                 |---------------------------------------------->|
                 |                                               |
                 |(2) FloorRequestStatus                         |
                 |Transaction ID: 123                            |
                 |User ID: 234                                   |
                 |FLOOR-REQUEST-INFORMATION                      |
                 |      Floor Request ID: 789                    |
                 |      OVERALL-REQUEST-STATUS                   |
                 |              Request Status: Pending          |
                 |      FLOOR-REQUEST-STATUS                     |
                 |            Floor ID: 543                      |
                 |<----------------------------------------------|
                 |                                               |
                 |(3) FloorRequestStatus                         |
                 |Transaction ID: 4098                           |
                 |User ID: 234                                   |
                 |FLOOR-REQUEST-INFORMATION                      |
                 |      Floor Request ID: 789                    |
                 |      OVERALL-REQUEST-STATUS                   |
                 |              Request Status: Accepted         |
                 |              Queue Position: 1st              |
                 |      FLOOR-REQUEST-STATUS                     |
                 |            Floor ID: 543                      |
                 |<----------------------------------------------|
                 |                                               |
                 |(4) FloorRequestStatusAck                      |



Kristensen, et al.       Expires April 28, 2011                [Page 17]


Internet-Draft               BFCP-Unreliable                October 2010


                 |Transaction ID: 4098                           |
                 |User ID: 234                                   |
                 |---------------------------------------------->|
                 |                                               |
                 |(5) FloorRequestStatus                         |
                 |Transaction ID: 4130                           |
                 |User ID: 234                                   |
                 |FLOOR-REQUEST-INFORMATION                      |
                 |      Floor Request ID: 789                    |
                 |      OVERALL-REQUEST-STATUS                   |
                 |              Request Status: Granted          |
                 |      FLOOR-REQUEST-STATUS                     |
                 |            Floor ID: 543                      |
                 |<----------------------------------------------|
                 |                                               |
                 |(6) FloorRequestStatusAck                      |
                 |Transaction ID: 4130                           |
                 |User ID: 234                                   |
                 |---------------------------------------------->|
                 |                                               |
                 |(7) FloorRelease                               |
                 |Transaction ID: 154                            |
                 |User ID: 234                                   |
                 |FLOOR-REQUEST-ID: 789                          |
                 |---------------------------------------------->|
                 |                                               |
                 |(8) FloorRequestStatus                         |
                 |Transaction ID: 154                            |
                 |User ID: 234                                   |
                 |FLOOR-REQUEST-INFORMATION                      |
                 |      Floor Request ID: 789                    |
                 |      OVERALL-REQUEST-STATUS                   |
                 |              Request Status: Released         |
                 |      FLOOR-REQUEST-STATUS                     |
                 |            Floor ID: 543                      |
                 |<----------------------------------------------|

                Figure 7: Requesting and releasing a floor

   Note that in Figure 7, the FloorRequestStatus message from the floor
   control server to the floor participant is a transaction-closing
   message as a response to the client-initiated transaction with
   Transaction ID 154.  It does not and SHOULD NOT be followed by a
   FloorRequestStatusAck message from the floor participant to the floor
   control server.


         Floor Participant                                 Floor Control



Kristensen, et al.       Expires April 28, 2011                [Page 18]


Internet-Draft               BFCP-Unreliable                October 2010


                                                              Server
                 |(1) FloorQuery                                 |
                 |Transaction ID: 257                            |
                 |User ID: 234                                   |
                 |FLOOR-ID: 543                                  |
                 |---------------------------------------------->|
                 |                                               |
                 |(2) FloorStatus                                |
                 |Transaction ID: 257                            |
                 |User ID: 234                                   |
                 |FLOOR-ID:543                                   |
                 |FLOOR-REQUEST-INFORMATION                      |
                 |      Floor Request ID: 764                    |
                 |      OVERALL-REQUEST-STATUS                   |
                 |              Request Status: Accepted         |
                 |              Queue Position: 1st              |
                 |      FLOOR-REQUEST-STATUS                     |
                 |            Floor ID: 543                      |
                 |      BENEFICIARY-INFORMATION                  |
                 |                  Beneficiary ID: 124          |
                 |FLOOR-REQUEST-INFORMATION                      |
                 |      Floor Request ID: 635                    |
                 |      OVERALL-REQUEST-STATUS                   |
                 |              Request Status: Accepted         |
                 |              Queue Position: 2nd              |
                 |      FLOOR-REQUEST-STATUS                     |
                 |            Floor ID: 543                      |
                 |      BENEFICIARY-INFORMATION                  |
                 |                  Beneficiary ID: 154          |
                 |<----------------------------------------------|
                 |                                               |
                 |(3) FloorStatus                                |
                 |Transaction ID: 4319                           |
                 |User ID: 234                                   |
                 |FLOOR-ID:543                                   |
                 |FLOOR-REQUEST-INFORMATION                      |
                 |      Floor Request ID: 764                    |
                 |      OVERALL-REQUEST-STATUS                   |
                 |              Request Status: Granted          |
                 |      FLOOR-REQUEST-STATUS                     |
                 |            Floor ID: 543                      |
                 |      BENEFICIARY-INFORMATION                  |
                 |                  Beneficiary ID: 124          |
                 |FLOOR-REQUEST-INFORMATION                      |
                 |      Floor Request ID: 635                    |
                 |      OVERALL-REQUEST-STATUS                   |
                 |              Request Status: Accepted         |
                 |              Queue Position: 1st              |



Kristensen, et al.       Expires April 28, 2011                [Page 19]


Internet-Draft               BFCP-Unreliable                October 2010


                 |      FLOOR-REQUEST-STATUS                     |
                 |            Floor ID: 543                      |
                 |      BENEFICIARY-INFORMATION                  |
                 |                  Beneficiary ID: 154          |
                 |<----------------------------------------------|
                 |                                               |
                 |(4) FloorStatusAck                             |
                 |Transaction ID: 4319                           |
                 |User ID: 234                                   |
                 |---------------------------------------------->|
                 |                                               |
                 |(5) FloorStatus                                |
                 |Transaction ID: 4392                           |
                 |User ID: 234                                   |
                 |FLOOR-ID:543                                   |
                 |FLOOR-REQUEST-INFORMATION                      |
                 |      Floor Request ID: 635                    |
                 |      OVERALL-REQUEST-STATUS                   |
                 |              Request Status: Granted          |
                 |      FLOOR-REQUEST-STATUS                     |
                 |            Floor ID: 543                      |
                 |      BENEFICIARY-INFORMATION                  |
                 |                  Beneficiary ID: 154          |
                 |<----------------------------------------------|
                 |                                               |
                 |(6) FloorStatusAck                             |
                 |Transaction ID: 4392                           |
                 |User ID: 234                                   |
                 |---------------------------------------------->|

           Figure 8: Obtaining status information about a floor


4.  Revision of RFC4583

   This section details revisions to [RFC4583], the SDP format for
   specifying BFCP streams.  The section number to which updates apply
   are indicated in parentheses in the titles of the sub-sections below.

4.1.  Fields in the 'm' Line (3)

   The section shall be re-written to remove reference to the
   exclusivity of TCP as a transport for BFCP streams.

   1.  In paragraph four, "... will initiate its TCP connection ..."
       becomes "... will direct BFCP messages ..."





Kristensen, et al.       Expires April 28, 2011                [Page 20]


Internet-Draft               BFCP-Unreliable                October 2010


   2.  In paragraph four, delete "Since BFCP only runs on top of TCP,
       the port is always a TCP port."

   3.  In paragraph five, we now define three new values for the
       transport field, adding "UDP/BFCP" as the third symbol, changing
       "former" for "first", "latter" for "second", and adding a final
       clause defining the use of UDP/BFCP as being for when BFCP runs
       on top of UDP

4.2.  Security Considerations (10)

   In addition to the RFCs mentioned for TCP and TLS connections, the
   specifications for SRTP over DTLS [RFC5763] and [RFC5764] discuss
   security issues in detail.  Add references to them in the section.

   Editorial Note: Expanded analysis and discussion will be added after
   lower-layer security details is sorted out in Section 3.13.

4.3.  Registration of SDP 'proto' Values (11.1)

   This section should be renamed now that there are more values to
   register in the SDP parameters registry, with the following added to
   the table:

                       +--------------+-----------+
                       | Value        | Reference |
                       +--------------+-----------+
                       | UDP/BFCP     | RFC YYYY  |
                       | UDP/TLS/BFCP | RFC YYYY  |
                       +--------------+-----------+

                 Table 6: Value for the SDP 'proto' field


5.  Future Work

   This draft reflects a work in progress, with at least the following
   items to be documented and/or revised before soliciting adoption by
   the XCON working group:

   Adapting DTLS usage to BFCP:  Currently the DTLS-SRTP specifications
         [RFC5763] and [RFC5764] are referenced merely as sligtly
         related and partially similar to the intended BFCP usage of
         DTLS.  The next version of this draft will add details to
         Section 3.13.  This consideration applies to the two security
         consideration sections as well, namely Section 3.30 and
         Section 4.2.  Adding examples on DTLS usage in the call setup
         phase will provide guidance to implementors.



Kristensen, et al.       Expires April 28, 2011                [Page 21]


Internet-Draft               BFCP-Unreliable                October 2010


   Fragmentation:  It has been observed that BFCP message structures can
         grow to be sufficiently large that they exceed the typical MTU
         threshold for local area networks (assumed here as 1500
         octets).  For example, a FloorStatus message with multiple
         FLOOR-REQUEST-INFORMATION attributes that contain detailed
         STATUS-INFO in the OVERALL-REQUEST-STATUS and FLOOR-REQUEST-
         STATUS attributes.  A strategy for coping with such fragmented
         messages is required.  Currently, this is held with a broad-
         sweeping statement of intent that implementations should
         restrict the size of their messages.  Further refinement might
         be required, such as an applicability statement on those BFCP
         messages and/or attributes deemed as inappropriate for use over
         transports where fragmentation is a concern, or further
         protocol specification to eradicate fragmentation as an issue.
         A mechanism for splitting into additive messages might be
         considered.

   Example signaling flows:  A later version of this draft will include
         further examples of signaling exchanges over unreliable
         transport as a visual aid and reference for implementors.
         Including updated transactions, message retransmission, usage
         of DTLS during call setup and combined usage of DTLS and STUN.


6.  Acknowledgements

   The team working on this draft are: Trond G. Andersen, Charles Eckel,
   Tom Kristensen, Eoin McLeod, Geir A. Sandbakken and Mark K. Thompson
   at Cisco; Alfred E. Heggestad at Telio Telecom.


7.  References

7.1.  Normative References

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

   [RFC3264]  Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
              with Session Description Protocol (SDP)", RFC 3264,
              June 2002.

   [RFC4347]  Rescorla, E. and N. Modadugu, "Datagram Transport Layer
              Security", RFC 4347, April 2006.

   [RFC4582]  Camarillo, G., Ott, J., and K. Drage, "The Binary Floor
              Control Protocol (BFCP)", RFC 4582, November 2006.




Kristensen, et al.       Expires April 28, 2011                [Page 22]


Internet-Draft               BFCP-Unreliable                October 2010


   [RFC4583]  Camarillo, G., "Session Description Protocol (SDP) Format
              for Binary Floor Control Protocol (BFCP) Streams",
              RFC 4583, November 2006.

7.2.  Informative References

   [I-D.ietf-mmusic-ice-tcp]
              Rosenberg, J., Keranen, A., Lowekamp, B., and A. Roach,
              "TCP Candidates with Interactive Connectivity
              Establishment (ICE)", draft-ietf-mmusic-ice-tcp-10 (work
              in progress), October 2010.

   [RFC3261]  Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
              A., Peterson, J., Sparks, R., Handley, M., and E.
              Schooler, "SIP: Session Initiation Protocol", RFC 3261,
              June 2002.

   [RFC5245]  Rosenberg, J., "Interactive Connectivity Establishment
              (ICE): A Protocol for Network Address Translator (NAT)
              Traversal for Offer/Answer Protocols", RFC 5245,
              April 2010.

   [RFC5405]  Eggert, L. and G. Fairhurst, "Unicast UDP Usage Guidelines
              for Application Designers", BCP 145, RFC 5405,
              November 2008.

   [RFC5763]  Fischl, J., Tschofenig, H., and E. Rescorla, "Framework
              for Establishing a Secure Real-time Transport Protocol
              (SRTP) Security Context Using Datagram Transport Layer
              Security (DTLS)", RFC 5763, May 2010.

   [RFC5764]  McGrew, D. and E. Rescorla, "Datagram Transport Layer
              Security (DTLS) Extension to Establish Keys for the Secure
              Real-time Transport Protocol (SRTP)", RFC 5764, May 2010.


Appendix A.  Change History

A.1.  draft-sandbakken-dispatch-bfcp-udp-00 to -01

   1.  Decision made to not increase the protocol version number as a
       result of this extension.  Certain aspects of this draft require
       different behaviors depending on whether a reliable or unreliable
       transport is being used, e.g. server-initiated transactions
       having Transaction ID 0 over reliable transports without
       acknowledgements versus non-zero and active-unique with an
       acknowledgement message when entities communicate over unreliable
       transports.  As the graceful-close behaviour of [RFC4582] is



Kristensen, et al.       Expires April 28, 2011                [Page 23]


Internet-Draft               BFCP-Unreliable                October 2010


       still allowed for TCP-based implementations without mandating the
       use of the new Goodbye message, there is no need to change the
       version number.

   2.  Removed the - a bit too verbose - rationale/motivation text
       describing background and why other approaches where not chosen.
       Was OK for a -00 draft, not strictly needed.

   3.  Not mandate ICE as a SHALL, but leave it as a non-mandatory way
       of solving the potential need for NAT/FW traversal.

   4.  Emphasized that the reference to DTLS-SRTP are merely
       informational.

   5.  A dash of polish and nitpicking added, some typoes fixed.

A.2.  draft-sandbakken-xcon-bfcp-udp-02 to
      draft-sandbakken-dispatch-bfcp-udp-00

   1.  Draft name change.  As XCON WG is closing this draft is submitted
       to Dispatch WG as the arena of discussion.

   2.  Moved Transaction Identifier bit (I) from the Transaction ID to
       one of the current 5 reserved bits.  Keep current Transaction ID
       syntax and semantics.  Avoid potential problems with existing TCP
       based implentations.

   3.  The way congestion control is taken care of is explained, with
       reference to [RFC5405].  One message per RTT.  Backoff and
       normative behavior for timer T1 clarified.

   4.  Mandated support for DTLS in case unreliable transport (i.e.
       UDP) is implemented.  Details and examples to be included.  Model
       after [RFC5763], details on how to adapt the SRTP associated
       details to BFCP and whether a reference or copying the text
       across and changing is needed.

   5.  Added the Rationale and Scope section to position and explain the
       motivation for this draft more in detail.

   6.  A number of typoes and editorial changes.

A.3.  draft-sandbakken-xcon-bfcp-udp-01 to -02

   1.  Stepped away from changing semantics and directionality of Hello
       and HelloAck messages for pinhole establishment and keep-alive in
       favor of ICE toolset, particularly as this would have not
       resolved connectivity establishment as a precursor to deployment



Kristensen, et al.       Expires April 28, 2011                [Page 24]


Internet-Draft               BFCP-Unreliable                October 2010


       of DTLS [RFC4347] as a transport security mechanism.

   2.  Change to COMMON-HEADER to reserve bit-16 of Transaction ID to
       show originator of transaction such that request/response and
       response/acknowledgement mapping can be maintained without
       colliding randomly chosen Transaction IDs.  This also avoids a
       three-way handshake scenario around FloorRequest where the
       implicit acknowledgement (in FloorRequestStatus) might also be
       interpreted as a transaction openening request on the part of the
       floor control server.

   3.  Defined additional timer (T2) to soak up lost responses without
       additional processing.

   4.  Restricted outstanding transactions to only one in-flight per
       direction at any one time to mitigate re-ordering issues.

   5.  Defined entity behavior when transactions timeout.

   6.  Specified initial suggestion for how to minimise fragmentation of
       messages.

   7.  Removed consideration of TCP-over-UDP after internal review.

   8.  Re-stated DTLS as likely preferred mechanism of securing
       transport, although this investigation is on-going.

A.4.  draft-sandbakken-xcon-bfcp-udp-00 to -01

   1.  Refactored to a format that represents explicit changes to base
       RFCs.

   2.  Introduction of issues currently under investigation that
       preclude adoption.

   3.  Specified retransmission timer for requests.


Authors' Addresses

   Tom Kristensen
   Cisco
   Philip Pedersens vei 22
   N-1366 Lysaker
   Norway

   Email: tomkrist@cisco.com, tomkri@ifi.uio.no




Kristensen, et al.       Expires April 28, 2011                [Page 25]


Internet-Draft               BFCP-Unreliable                October 2010


   Mark K. Thompson
   Cisco
   Ruscombe Business Park
   Ruscombe, England
   UK

   Email: markth2@cisco.com


   Geir A. Sandbakken
   Cisco
   Philip Pedersens vei 22
   N-1366 Lysaker
   Norway

   Email: geirsand@cisco.com


   Trond G. Andersen
   Cisco
   Philip Pedersens vei 22
   N-1366 Lysaker
   Norway

   Email: trondand@cisco.com


   Eoin McLeod
   Cisco
   Ruscombe Business Park
   Ruscombe, England
   UK

   Email: eoimcleo@cisco.com

















Kristensen, et al.       Expires April 28, 2011                [Page 26]


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