draft-ietf-bfcpbis-rfc4582bis-10.txt   draft-ietf-bfcpbis-rfc4582bis-11.txt 
BFCPbis Working Group G. Camarillo BFCPbis Working Group G. Camarillo
Internet-Draft Ericsson Internet-Draft Ericsson
Obsoletes: 4582 (if approved) K. Drage Obsoletes: 4582 (if approved) K. Drage
Intended status: Standards Track Alcatel-Lucent Intended status: Standards Track Alcatel-Lucent
Expires: May 8, 2014 T. Kristensen Expires: August 19, 2014 T. Kristensen
Cisco Cisco
J. Ott J. Ott
Aalto University Aalto University
C. Eckel C. Eckel
Cisco Cisco
November 4, 2013 February 15, 2014
The Binary Floor Control Protocol (BFCP) The Binary Floor Control Protocol (BFCP)
draft-ietf-bfcpbis-rfc4582bis-10 draft-ietf-bfcpbis-rfc4582bis-11
Abstract Abstract
Floor control is a means to manage joint or exclusive access to Floor control is a means to manage joint or exclusive access to
shared resources in a (multiparty) conferencing environment. shared resources in a (multiparty) conferencing environment.
Thereby, floor control complements other functions -- such as Thereby, floor control complements other functions -- such as
conference and media session setup, conference policy manipulation, conference and media session setup, conference policy manipulation,
and media control -- that are realized by other protocols. and media control -- that are realized by other protocols.
This document specifies the Binary Floor Control Protocol (BFCP). This document specifies the Binary Floor Control Protocol (BFCP).
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 8, 2014. This Internet-Draft will expire on August 19, 2014.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
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5.3.13. Error . . . . . . . . . . . . . . . . . . . . . . . . 37 5.3.13. Error . . . . . . . . . . . . . . . . . . . . . . . . 37
5.3.14. FloorRequestStatusAck . . . . . . . . . . . . . . . . 38 5.3.14. FloorRequestStatusAck . . . . . . . . . . . . . . . . 38
5.3.15. FloorStatusAck . . . . . . . . . . . . . . . . . . . . 38 5.3.15. FloorStatusAck . . . . . . . . . . . . . . . . . . . . 38
5.3.16. Goodbye . . . . . . . . . . . . . . . . . . . . . . . 38 5.3.16. Goodbye . . . . . . . . . . . . . . . . . . . . . . . 38
5.3.17. GoodbyeAck . . . . . . . . . . . . . . . . . . . . . . 38 5.3.17. GoodbyeAck . . . . . . . . . . . . . . . . . . . . . . 38
6. Transport . . . . . . . . . . . . . . . . . . . . . . . . . . 39 6. Transport . . . . . . . . . . . . . . . . . . . . . . . . . . 39
6.1. Reliable Transport . . . . . . . . . . . . . . . . . . . . 39 6.1. Reliable Transport . . . . . . . . . . . . . . . . . . . . 39
6.2. Unreliable Transport . . . . . . . . . . . . . . . . . . . 40 6.2. Unreliable Transport . . . . . . . . . . . . . . . . . . . 40
6.2.1. Congestion Control . . . . . . . . . . . . . . . . . . 42 6.2.1. Congestion Control . . . . . . . . . . . . . . . . . . 42
6.2.2. ICMP Error Handling . . . . . . . . . . . . . . . . . 42 6.2.2. ICMP Error Handling . . . . . . . . . . . . . . . . . 42
6.2.3. Fragmentation Handling . . . . . . . . . . . . . . . . 42 6.2.3. Fragmentation Handling . . . . . . . . . . . . . . . . 43
6.2.4. NAT Traversal . . . . . . . . . . . . . . . . . . . . 44 6.2.4. NAT Traversal . . . . . . . . . . . . . . . . . . . . 44
7. Lower-Layer Security . . . . . . . . . . . . . . . . . . . . . 44 7. Lower-Layer Security . . . . . . . . . . . . . . . . . . . . . 44
8. Protocol Transactions . . . . . . . . . . . . . . . . . . . . 45 8. Protocol Transactions . . . . . . . . . . . . . . . . . . . . 45
8.1. Client Behavior . . . . . . . . . . . . . . . . . . . . . 46 8.1. Client Behavior . . . . . . . . . . . . . . . . . . . . . 46
8.2. Server Behavior . . . . . . . . . . . . . . . . . . . . . 46 8.2. Server Behavior . . . . . . . . . . . . . . . . . . . . . 46
8.3. Timers . . . . . . . . . . . . . . . . . . . . . . . . . . 46 8.3. Timers . . . . . . . . . . . . . . . . . . . . . . . . . . 47
8.3.1. Request Retransmission Timer, T1 . . . . . . . . . . . 46 8.3.1. Request Retransmission Timer, T1 . . . . . . . . . . . 47
8.3.2. Response Retransmission Timer, T2 . . . . . . . . . . 47 8.3.2. Response Retransmission Timer, T2 . . . . . . . . . . 47
8.3.3. Timer Values . . . . . . . . . . . . . . . . . . . . . 47 8.3.3. Timer Values . . . . . . . . . . . . . . . . . . . . . 47
9. Authentication and Authorization . . . . . . . . . . . . . . . 47 9. Authentication and Authorization . . . . . . . . . . . . . . . 48
9.1. TLS/DTLS Based Mutual Authentication . . . . . . . . . . . 48 9.1. TLS/DTLS Based Mutual Authentication . . . . . . . . . . . 48
10. Floor Participant Operations . . . . . . . . . . . . . . . . . 48 10. Floor Participant Operations . . . . . . . . . . . . . . . . . 49
10.1. Requesting a Floor . . . . . . . . . . . . . . . . . . . . 49 10.1. Requesting a Floor . . . . . . . . . . . . . . . . . . . . 49
10.1.1. Sending a FloorRequest Message . . . . . . . . . . . . 49 10.1.1. Sending a FloorRequest Message . . . . . . . . . . . . 49
10.1.2. Receiving a Response . . . . . . . . . . . . . . . . . 50 10.1.2. Receiving a Response . . . . . . . . . . . . . . . . . 50
10.1.3. Reception of a Subsequent FloorRequestStatus 10.1.3. Reception of a Subsequent FloorRequestStatus
Message . . . . . . . . . . . . . . . . . . . . . . . 51 Message . . . . . . . . . . . . . . . . . . . . . . . 51
10.2. Cancelling a Floor Request and Releasing a Floor . . . . . 51 10.2. Cancelling a Floor Request and Releasing a Floor . . . . . 52
10.2.1. Sending a FloorRelease Message . . . . . . . . . . . . 51 10.2.1. Sending a FloorRelease Message . . . . . . . . . . . . 52
10.2.2. Receiving a Response . . . . . . . . . . . . . . . . . 52 10.2.2. Receiving a Response . . . . . . . . . . . . . . . . . 52
11. Chair Operations . . . . . . . . . . . . . . . . . . . . . . . 52 11. Chair Operations . . . . . . . . . . . . . . . . . . . . . . . 53
11.1. Sending a ChairAction Message . . . . . . . . . . . . . . 52 11.1. Sending a ChairAction Message . . . . . . . . . . . . . . 53
11.2. Receiving a Response . . . . . . . . . . . . . . . . . . . 54 11.2. Receiving a Response . . . . . . . . . . . . . . . . . . . 54
12. General Client Operations . . . . . . . . . . . . . . . . . . 54 12. General Client Operations . . . . . . . . . . . . . . . . . . 55
12.1. Requesting Information about Floors . . . . . . . . . . . 54 12.1. Requesting Information about Floors . . . . . . . . . . . 55
12.1.1. Sending a FloorQuery Message . . . . . . . . . . . . . 54 12.1.1. Sending a FloorQuery Message . . . . . . . . . . . . . 55
12.1.2. Receiving a Response . . . . . . . . . . . . . . . . . 55 12.1.2. Receiving a Response . . . . . . . . . . . . . . . . . 55
12.1.3. Reception of a Subsequent FloorStatus Message . . . . 56 12.1.3. Reception of a Subsequent FloorStatus Message . . . . 56
12.2. Requesting Information about Floor Requests . . . . . . . 56 12.2. Requesting Information about Floor Requests . . . . . . . 56
12.2.1. Sending a FloorRequestQuery Message . . . . . . . . . 56 12.2.1. Sending a FloorRequestQuery Message . . . . . . . . . 57
12.2.2. Receiving a Response . . . . . . . . . . . . . . . . . 56 12.2.2. Receiving a Response . . . . . . . . . . . . . . . . . 57
12.3. Requesting Information about a User . . . . . . . . . . . 57 12.3. Requesting Information about a User . . . . . . . . . . . 57
12.3.1. Sending a UserQuery Message . . . . . . . . . . . . . 57 12.3.1. Sending a UserQuery Message . . . . . . . . . . . . . 58
12.3.2. Receiving a Response . . . . . . . . . . . . . . . . . 58 12.3.2. Receiving a Response . . . . . . . . . . . . . . . . . 58
12.4. Obtaining the Capabilities of a Floor Control Server . . . 58 12.4. Obtaining the Capabilities of a Floor Control Server . . . 59
12.4.1. Sending a Hello Message . . . . . . . . . . . . . . . 58 12.4.1. Sending a Hello Message . . . . . . . . . . . . . . . 59
12.4.2. Receiving Responses . . . . . . . . . . . . . . . . . 58 12.4.2. Receiving Responses . . . . . . . . . . . . . . . . . 59
13. Floor Control Server Operations . . . . . . . . . . . . . . . 59 13. Floor Control Server Operations . . . . . . . . . . . . . . . 59
13.1. Reception of a FloorRequest Message . . . . . . . . . . . 59 13.1. Reception of a FloorRequest Message . . . . . . . . . . . 60
13.1.1. Generating the First FloorRequestStatus Message . . . 60 13.1.1. Generating the First FloorRequestStatus Message . . . 60
13.1.2. Generation of Subsequent FloorRequestStatus 13.1.2. Generation of Subsequent FloorRequestStatus
Messages . . . . . . . . . . . . . . . . . . . . . . . 61 Messages . . . . . . . . . . . . . . . . . . . . . . . 62
13.2. Reception of a FloorRequestQuery Message . . . . . . . . . 62 13.2. Reception of a FloorRequestQuery Message . . . . . . . . . 63
13.3. Reception of a UserQuery Message . . . . . . . . . . . . . 64 13.3. Reception of a UserQuery Message . . . . . . . . . . . . . 64
13.4. Reception of a FloorRelease Message . . . . . . . . . . . 65 13.4. Reception of a FloorRelease Message . . . . . . . . . . . 66
13.5. Reception of a FloorQuery Message . . . . . . . . . . . . 66 13.5. Reception of a FloorQuery Message . . . . . . . . . . . . 67
13.5.1. Generation of the First FloorStatus Message . . . . . 67 13.5.1. Generation of the First FloorStatus Message . . . . . 67
13.5.2. Generation of Subsequent FloorStatus Messages . . . . 68 13.5.2. Generation of Subsequent FloorStatus Messages . . . . 69
13.6. Reception of a ChairAction Message . . . . . . . . . . . . 69 13.6. Reception of a ChairAction Message . . . . . . . . . . . . 69
13.7. Reception of a Hello Message . . . . . . . . . . . . . . . 70 13.7. Reception of a Hello Message . . . . . . . . . . . . . . . 70
13.8. Error Message Generation . . . . . . . . . . . . . . . . . 70 13.8. Error Message Generation . . . . . . . . . . . . . . . . . 71
14. Security Considerations . . . . . . . . . . . . . . . . . . . 71 14. Security Considerations . . . . . . . . . . . . . . . . . . . 71
15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 72 15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 72
15.1. Attribute Subregistry . . . . . . . . . . . . . . . . . . 72 15.1. Attribute Subregistry . . . . . . . . . . . . . . . . . . 72
15.2. Primitive Subregistry . . . . . . . . . . . . . . . . . . 73 15.2. Primitive Subregistry . . . . . . . . . . . . . . . . . . 73
15.3. Request Status Subregistry . . . . . . . . . . . . . . . . 74 15.3. Request Status Subregistry . . . . . . . . . . . . . . . . 74
15.4. Error Code Subregistry . . . . . . . . . . . . . . . . . . 75 15.4. Error Code Subregistry . . . . . . . . . . . . . . . . . . 75
16. Changes from RFC 4582 . . . . . . . . . . . . . . . . . . . . 76 16. Changes from RFC 4582 . . . . . . . . . . . . . . . . . . . . 76
16.1. Extensions for an unreliable transport . . . . . . . . . . 76 16.1. Extensions for an unreliable transport . . . . . . . . . . 76
16.2. Other changes . . . . . . . . . . . . . . . . . . . . . . 78 16.2. Other changes . . . . . . . . . . . . . . . . . . . . . . 77
17. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 78 17. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 78
18. References . . . . . . . . . . . . . . . . . . . . . . . . . . 78 18. References . . . . . . . . . . . . . . . . . . . . . . . . . . 79
18.1. Normative References . . . . . . . . . . . . . . . . . . . 78 18.1. Normative References . . . . . . . . . . . . . . . . . . . 79
18.2. Informational References . . . . . . . . . . . . . . . . . 79 18.2. Informational References . . . . . . . . . . . . . . . . . 79
Appendix A. Example Call Flows for BFCP over an Unreliable Appendix A. Example Call Flows for BFCP over an Unreliable
Transport . . . . . . . . . . . . . . . . . . . . . . 81 Transport . . . . . . . . . . . . . . . . . . . . . . 81
Appendix B. Motivation for Supporting an Unreliable Transport . . 84 Appendix B. Motivation for Supporting an Unreliable Transport . . 84
B.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 85 B.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 85
B.1.1. Alternatives Considered . . . . . . . . . . . . . . . 86 B.1.1. Alternatives Considered . . . . . . . . . . . . . . . 86
B.1.1.1. ICE TCP . . . . . . . . . . . . . . . . . . . . . 86 B.1.1.1. ICE TCP . . . . . . . . . . . . . . . . . . . . . 86
B.1.1.2. Teredo . . . . . . . . . . . . . . . . . . . . . . 87 B.1.1.2. Teredo . . . . . . . . . . . . . . . . . . . . . . 87
B.1.1.3. GUT . . . . . . . . . . . . . . . . . . . . . . . 87 B.1.1.3. GUT . . . . . . . . . . . . . . . . . . . . . . . 87
B.1.1.4. UPnP IGD . . . . . . . . . . . . . . . . . . . . . 87 B.1.1.4. UPnP IGD . . . . . . . . . . . . . . . . . . . . . 87
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Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 89 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 89
1. Introduction 1. Introduction
Within a conference, some applications need to manage the access to a Within a conference, some applications need to manage the access to a
set of shared resources, such as the right to send media to a set of shared resources, such as the right to send media to a
particular media session. Floor control enables such applications to particular media session. Floor control enables such applications to
provide users with coordinated (shared or exclusive) access to these provide users with coordinated (shared or exclusive) access to these
resources. resources.
The Requirements for Floor Control Protocol [11] list a set of The Requirements for Floor Control Protocol [13] list a set of
requirements that need to be met by floor control protocols. The requirements that need to be met by floor control protocols. The
Binary Floor Control Protocol (BFCP), which is specified in this Binary Floor Control Protocol (BFCP), which is specified in this
document, meets these requirements. document, meets these requirements.
In addition, BFCP has been designed so that it can be used in low- In addition, BFCP has been designed so that it can be used in low-
bandwidth environments. The binary encoding used by BFCP achieves a bandwidth environments. The binary encoding used by BFCP achieves a
small message size (when message signatures are not used) that keeps small message size (when message signatures are not used) that keeps
the time it takes to transmit delay-sensitive BFCP messages to a the time it takes to transmit delay-sensitive BFCP messages to a
minimum. Delay-sensitive BFCP messages include FloorRequest, minimum. Delay-sensitive BFCP messages include FloorRequest,
FloorRelease, FloorRequestStatus, and ChairAction. It is expected FloorRelease, FloorRequestStatus, and ChairAction. It is expected
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Participant: An entity that acts as a floor participant, as a media Participant: An entity that acts as a floor participant, as a media
participant, or as both. participant, or as both.
BFCP Connection: A transport association between BFCP entities, used BFCP Connection: A transport association between BFCP entities, used
to exchange BFCP messages. to exchange BFCP messages.
3. Scope 3. Scope
As stated earlier, BFCP is a protocol to coordinate access to shared As stated earlier, BFCP is a protocol to coordinate access to shared
resources in a conference following the requirements defined in [11]. resources in a conference following the requirements defined in [13].
Floor control complements other functions defined in the XCON Floor control complements other functions defined in the XCON
conferencing framework [12]. The floor control protocol BFCP defined conferencing framework [14]. The floor control protocol BFCP defined
in this document only specifies a means to arbitrate access to in this document only specifies a means to arbitrate access to
floors. The rules and constraints for floor arbitration and the floors. The rules and constraints for floor arbitration and the
results of floor assignments are outside the scope of this document results of floor assignments are outside the scope of this document
and are defined by other protocols [12]. and are defined by other protocols [14].
Figure 1 shows the tasks that BFCP can perform. Figure 1 shows the tasks that BFCP can perform.
+---------+ +---------+
| Floor | | Floor |
| Chair | | Chair |
| | | |
+---------+ +---------+
^ | ^ |
| | | |
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the scope of BFCP, some of these out-of-scope tasks relate to floor the scope of BFCP, some of these out-of-scope tasks relate to floor
control and are essential for creating floors and establishing BFCP control and are essential for creating floors and establishing BFCP
connections between different entities. In the following connections between different entities. In the following
subsections, we discuss some of these tasks and mechanisms to perform subsections, we discuss some of these tasks and mechanisms to perform
them. them.
3.1. Floor Creation 3.1. Floor Creation
The association of a given floor with a resource or a set of The association of a given floor with a resource or a set of
resources (e.g., media streams) is out of the scope of BFCP as resources (e.g., media streams) is out of the scope of BFCP as
described in [12]. Floor creation and termination are also outside described in [14]. Floor creation and termination are also outside
the scope of BFCP; these aspects are handled using the conference the scope of BFCP; these aspects are handled using the conference
control protocol for manipulating the conference object. control protocol for manipulating the conference object.
Consequently, the floor control server needs to stay up to date on Consequently, the floor control server needs to stay up to date on
changes to the conference object (e.g., when a new floor is created). changes to the conference object (e.g., when a new floor is created).
Conference control clients using CCMP [17] can specify such floor- Conference control clients using CCMP [18] can specify such floor-
related settings by editing the floor-information section of the related settings in the <floor-information> element [17] of the to-be
to-be created conference object provided in the body of a CCMP created conference object provided in the body of a CCMP confRequest/
confRequest/create message issued to the conference control server. create message issued to the conference control server.
3.2. Obtaining Information to Contact a Floor Control Server 3.2. Obtaining Information to Contact a Floor Control Server
A client needs a set of data in order to establish a BFCP connection A client needs a set of data in order to establish a BFCP connection
to a floor control server. These data include the transport address to a floor control server. This data includes the transport address
of the server, the conference identifier, and a user identifier. of the server, the conference identifier, and a user identifier.
Clients can obtain this information in different ways. One is to use Clients can obtain this information in different ways. One is to use
an SDP offer/answer [10] exchange, which is described in [7]. How to an SDP offer/answer [12] exchange, which is described in [9]. How to
establish a connection to a BFCP floor control server outside the establish a connection to a BFCP floor control server outside the
context of an offer/answer exchange is described in [16]. Other context of an offer/answer exchange is described in [3]. Other
mechanisms are described in the XCON framework [12] (and other mechanisms are described in the XCON framework [14] (and other
related documents). related documents).
3.3. Obtaining Floor-Resource Associations 3.3. Obtaining Floor-Resource Associations
Floors are associated with resources. For example, a floor that Floors are associated with resources. For example, a floor that
controls who talks at a given time has a particular audio session as controls who talks at a given time has a particular audio session as
its associated resource. Associations between floors and resources its associated resource. Associations between floors and resources
are part of the conference object. are part of the conference object.
Floor participants and floor chairs need to know which resources are Floor participants and floor chairs need to know which resources are
associated with which floors. They can obtain this information by associated with which floors. They can obtain this information by
using different mechanisms, such as an SDP offer/answer [10] using different mechanisms, such as an SDP offer/answer [12]
exchange. How to use an SDP offer/answer exchange to obtain these exchange. How to use an SDP offer/answer exchange to obtain these
associations is described in [7]. associations is described in [9].
Note that floor participants perform SDP offer/answer exchanges Note that floor participants perform SDP offer/answer exchanges
with the conference focus of the conference. So, the conference with the conference focus of the conference. So, the conference
focus needs to obtain information about associations between focus needs to obtain information about associations between
floors and resources in order to be able to provide this floors and resources in order to be able to provide this
information to a floor participant in an SDP offer/answer information to a floor participant in an SDP offer/answer
exchange. exchange.
Other mechanisms for obtaining this information, including discussion Other mechanisms for obtaining this information, including discussion
of how the information is made available to a (SIP) Focus, are of how the information is made available to a (SIP) Focus, are
described in the XCON framework [12] (and other related documents). described in the XCON framework [14] (and other related documents).
According to the conferencing system policies, conference control According to the conferencing system policies, conference control
clients using CCMP [17] can modify the floor settings of a conference clients using CCMP [18] can modify the floor settings of a conference
by issuing CCMP confRequest/update messages providing the specific by issuing CCMP confRequest/update messages providing the specific
updates to the <floor-information> section of the target conference updates to the <floor-information> element of the target conference
object. More information about CCMP and BFCP interaction can be object. More information about CCMP and BFCP interaction can be
found in [18]. found in [19].
3.4. Privileges of Floor Control 3.4. Privileges of Floor Control
A participant whose floor request is granted has the right to use (in A participant whose floor request is granted has the right to use the
a certain way) the resource or resources associated with the floor resource or resources associated with the floor that was requested.
that was requested. For example, the participant may have the right For example, the participant may have the right to send media over a
to send media over a particular audio stream. particular audio stream.
Nevertheless, holding a floor does not imply that others will not be Nevertheless, holding a floor does not imply that others will not be
able to use its associated resources at the same time, even if they able to use its associated resources at the same time, even if they
do not have the right to do so. Determination of which media do not have the right to do so. Determination of which media
participants can actually use the resources in the conference is participants can actually use the resources in the conference is
discussed in the XCON Framework [12]. discussed in the XCON Framework [14].
4. Overview of Operation 4. Overview of Operation
This section provides a non-normative description of BFCP operations. This section provides a non-normative description of BFCP operations.
Section 4.1 describes the interface between floor participants and Section 4.1 describes the interface between floor participants and
floor control servers, and Section 4.2 describes the interface floor control servers, and Section 4.2 describes the interface
between floor chairs and floor control servers. between floor chairs and floor control servers.
BFCP messages, which use a TLV (Type-Length-Value) binary encoding, BFCP messages, which use a TLV (Type-Length-Value) binary encoding,
consist of a common header followed by a set of attributes. The consist of a common header followed by a set of attributes. The
skipping to change at page 17, line 4 skipping to change at page 17, line 4
| Transaction ID | User ID | | Transaction ID | User ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Fragment Offset (if F is set) | Fragment Length (if F is set) | | Fragment Offset (if F is set) | Fragment Length (if F is set) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: COMMON-HEADER format Figure 5: COMMON-HEADER format
Ver: This 3-bit field defines the version of BFCP that this message Ver: This 3-bit field defines the version of BFCP that this message
adheres to. This specification defines two versions: 1 and 2. The adheres to. This specification defines two versions: 1 and 2. The
version field MUST be set to 1 when using BFCP over a reliable version field MUST be set to 1 when using BFCP over a reliable
transport, i.e. as in [15]. The version field MUST be set to 2 when transport, i.e. as in [2]. The version field MUST be set to 2 when
using BFCP over an unreliable transport with the extensions specified using BFCP over an unreliable transport with the extensions specified
in this document. If an endpoint receives a message with an in this document. If an endpoint receives a message with an
unsupported version field value, the receiving server SHOULD send an unsupported version field value, the receiving server MUST send an
Error message with parameter value 12 (Unsupported Version) to Error message with parameter value 12 (Unsupported Version) to
indicate this. indicate this.
R: The Transaction Responder (R) flag-bit has relevance only for use R: The Transaction Responder (R) flag-bit has relevance only for use
of BFCP over an unreliable transport. When cleared, it indicates of BFCP over an unreliable transport. When cleared, it indicates
that this message is a request initiating a new transaction, and the that this message is a request initiating a new transaction, and the
Transaction ID that follows has been generated for this transaction. Transaction ID that follows has been generated for this transaction.
When set, it indicates that this message is a response to a previous When set, it indicates that this message is a response to a previous
request, and the Transaction ID that follows is the one associated request, and the Transaction ID that follows is the one associated
with that request. When BFCP is used over a reliable transport, the with that request. When BFCP is used over a reliable transport, the
flag has no significance and SHOULD be cleared by the sender and MUST flag has no significance and MUST be cleared by the sender and MUST
be ignored by the receiver. be ignored by the receiver.
F: The Fragmentation (F) flag-bit has relevance only for use of BFCP F: The Fragmentation (F) flag-bit has relevance only for use of BFCP
over an unreliable transport. When cleared, the message is not over an unreliable transport. When cleared, the message is not
fragmented. When set, it indicates that the message is a fragment of fragmented. When set, it indicates that the message is a fragment of
a large fragmented BFCP message. (The optional fields Fragment a large fragmented BFCP message. (The optional fields Fragment
Offset and Fragment Length described below are present only if the F Offset and Fragment Length described below are present only if the F
flag is set). When BFCP is used over a reliable transport, the flag flag is set). When BFCP is used over a reliable transport, the flag
has no significance and SHOULD be cleared by the sender and MUST be has no significance and MUST be cleared by the sender and MUST be
ignored by the receiver. ignored by the receiver.
Res: At this point, the 3 bits in the reserved field SHOULD be set to Res: At this point, the 3 bits in the reserved field MUST be set to
zero by the sender of the message and MUST be ignored by the zero by the sender of the message and MUST be ignored by the
receiver. receiver.
Primitive: This 8-bit field identifies the main purpose of the Primitive: This 8-bit field identifies the main purpose of the
message. The following primitive values are defined: message. The following primitive values are defined:
+-------+-----------------------+--------------------+ +-------+-----------------------+--------------------+
| Value | Primitive | Direction | | Value | Primitive | Direction |
+-------+-----------------------+--------------------+ +-------+-----------------------+--------------------+
| 1 | FloorRequest | P -> S | | 1 | FloorRequest | P -> S |
skipping to change at page 18, line 36 skipping to change at page 18, line 36
| | | P <- S ; Ch <- S | | | | P <- S ; Ch <- S |
+-------+-----------------------+--------------------+ +-------+-----------------------+--------------------+
S: Floor Control Server / P: Floor Participant / Ch: Floor Chair S: Floor Control Server / P: Floor Participant / Ch: Floor Chair
Table 1: BFCP primitives Table 1: BFCP primitives
Payload Length: This 16-bit field contains the length of the message Payload Length: This 16-bit field contains the length of the message
in 4-octet units, excluding the common header. If a Floor Control in 4-octet units, excluding the common header. If a Floor Control
Server receives a message with an incorrect Payload Length field Server receives a message with an incorrect Payload Length field
value, the receiving server SHOULD send an Error message with value, the receiving server MUST send an Error message with parameter
parameter value 13 (Incorrect Message Length) to indicate this. value 13 (Incorrect Message Length) to indicate this.
Note: BFCP is designed to achieve small message size, as explained Note: BFCP is designed to achieve small message size, as explained
in Section 1, and BFCP entities are REQUIRED to keep the BFCP in Section 1, and BFCP entities are REQUIRED to keep the BFCP
message size smaller than the size limited by the 16-bit Payload message size smaller than the size limited by the 16-bit Payload
Length field. To convey information not strictly related to floor Length field. To convey information not strictly related to floor
control, other protocols should be used such as the XCON framework control, other protocols should be used such as the XCON framework
(cf. Section 3). (cf. Section 3).
Conference ID: This 32-bit unsigned integer field identifies the Conference ID: This 32-bit unsigned integer field identifies the
conference the message belongs to. conference the message belongs to.
skipping to change at page 20, line 43 skipping to change at page 20, line 43
| 15 | FLOOR-REQUEST-INFORMATION | Grouped | | 15 | FLOOR-REQUEST-INFORMATION | Grouped |
| 16 | REQUESTED-BY-INFORMATION | Grouped | | 16 | REQUESTED-BY-INFORMATION | Grouped |
| 17 | FLOOR-REQUEST-STATUS | Grouped | | 17 | FLOOR-REQUEST-STATUS | Grouped |
| 18 | OVERALL-REQUEST-STATUS | Grouped | | 18 | OVERALL-REQUEST-STATUS | Grouped |
+------+---------------------------+---------------+ +------+---------------------------+---------------+
Table 2: BFCP attributes Table 2: BFCP attributes
M: The 'M' bit, known as the Mandatory bit, indicates whether support M: The 'M' bit, known as the Mandatory bit, indicates whether support
of the attribute is required. If a Floor Control Server receives an of the attribute is required. If a Floor Control Server receives an
unrecognized attribute with the 'M' bit set the server SHOULD send an unrecognized attribute with the 'M' bit set the server MUST send an
Error message with parameter value 4 (Unknown Mandatory Attribute) to Error message with parameter value 4 (Unknown Mandatory Attribute) to
indicate this. The 'M' bit is significant for extension attributes indicate this. The 'M' bit is significant for extension attributes
defined in other documents only. All attributes specified in this defined in other documents only. All attributes specified in this
document MUST be understood by the receiver so that the setting of document MUST be understood by the receiver so that the setting of
the 'M' bit is irrelevant for these. In all other cases, the the 'M' bit is irrelevant for these. In all other cases, the
unrecognized attribute is ignored but the message is processed. unrecognized attribute is ignored but the message is processed.
Length: This 8-bit field contains the length of the attribute in Length: This 8-bit field contains the length of the attribute in
octets, excluding any padding defined for specific attributes. The octets, excluding any padding defined for specific attributes. The
length of attributes that are not grouped includes the Type, 'M' bit, length of attributes that are not grouped includes the Type, 'M' bit,
skipping to change at page 22, line 50 skipping to change at page 22, line 50
+-------+----------+ +-------+----------+
| 0 | Lowest | | 0 | Lowest |
| 1 | Low | | 1 | Low |
| 2 | Normal | | 2 | Normal |
| 3 | High | | 3 | High |
| 4 | Highest | | 4 | Highest |
+-------+----------+ +-------+----------+
Table 3: Priority values Table 3: Priority values
Reserved: At this point, the 13 bits in the reserved field SHOULD be Reserved: At this point, the 13 bits in the reserved field MUST be
set to zero by the sender of the message and MUST be ignored by the set to zero by the sender of the message and MUST be ignored by the
receiver. receiver.
5.2.5. REQUEST-STATUS 5.2.5. REQUEST-STATUS
The following is the format of the REQUEST-STATUS attribute. The following is the format of the REQUEST-STATUS attribute.
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 25, line 17 skipping to change at page 25, line 17
codes do not apply. codes do not apply.
Error Specific Details: Present only for certain Error Codes. In Error Specific Details: Present only for certain Error Codes. In
this document, only for Error Code 4 (Unknown Mandatory Attribute). this document, only for Error Code 4 (Unknown Mandatory Attribute).
See Section 5.2.6.1 for its definition. See Section 5.2.6.1 for its definition.
Padding: One, two, or three octets of padding added so that the Padding: One, two, or three octets of padding added so that the
contents of the ERROR-CODE attribute is 32-bit aligned. If the contents of the ERROR-CODE attribute is 32-bit aligned. If the
attribute is already 32-bit aligned, no padding is needed. attribute is already 32-bit aligned, no padding is needed.
The Padding bits SHOULD be set to zero by the sender and MUST be The Padding bits MUST be set to zero by the sender and MUST be
ignored by the receiver. ignored by the receiver.
5.2.6.1. Error-Specific Details for Error Code 4 5.2.6.1. Error-Specific Details for Error Code 4
The following is the format of the Error-Specific Details field for The following is the format of the Error-Specific Details field for
Error Code 4. Error Code 4.
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 25, line 43 skipping to change at page 25, line 43
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Unknown Type|R| Unknown Type|R| | Unknown Type|R| Unknown Type|R|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 13: Unknown attributes format Figure 13: Unknown attributes format
Unknown Type: These 7-bit fields contain the Types of the attributes Unknown Type: These 7-bit fields contain the Types of the attributes
(which were present in the message that triggered the Error message) (which were present in the message that triggered the Error message)
that were unknown to the receiver. that were unknown to the receiver.
R: At this point, this bit is reserved. It SHOULD be set to zero by R: At this point, this bit is reserved. It MUST be set to zero by
the sender of the message and MUST be ignored by the receiver. the sender of the message and MUST be ignored by the receiver.
5.2.7. ERROR-INFO 5.2.7. ERROR-INFO
The following is the format of the ERROR-INFO attribute. The following is the format of the ERROR-INFO attribute.
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0 1 1 1|M| Length | | |0 0 0 0 1 1 1|M| Length | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| | | |
/ Text / / Text /
/ +-+-+-+-+-+-+-+-+ / +-+-+-+-+-+-+-+-+
| | Padding | | | Padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 14: ERROR-INFO format Figure 14: ERROR-INFO format
Text: This field contains UTF-8 [6] encoded text. Text: This field contains UTF-8 [8] encoded text.
In some situations, the contents of the Text field may be generated In some situations, the contents of the Text field may be generated
by an automaton. If this automaton has information about the by an automaton. If this automaton has information about the
preferred language of the receiver of a particular ERROR-INFO preferred language of the receiver of a particular ERROR-INFO
attribute, it MAY use this language to generate the Text field. attribute, it MAY use this language to generate the Text field.
Padding: One, two, or three octets of padding added so that the Padding: One, two, or three octets of padding added so that the
contents of the ERROR-INFO attribute is 32-bit aligned. The Padding contents of the ERROR-INFO attribute is 32-bit aligned. The Padding
bits SHOULD be set to zero by the sender and MUST be ignored by the bits MUST be set to zero by the sender and MUST be ignored by the
receiver. If the attribute is already 32-bit aligned, no padding is receiver. If the attribute is already 32-bit aligned, no padding is
needed. needed.
5.2.8. PARTICIPANT-PROVIDED-INFO 5.2.8. PARTICIPANT-PROVIDED-INFO
The following is the format of the PARTICIPANT-PROVIDED-INFO The following is the format of the PARTICIPANT-PROVIDED-INFO
attribute. attribute.
0 1 2 3 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 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
skipping to change at page 26, line 49 skipping to change at page 26, line 49
|0 0 0 1 0 0 0|M| Length | | |0 0 0 1 0 0 0|M| Length | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| | | |
/ Text / / Text /
/ +-+-+-+-+-+-+-+-+ / +-+-+-+-+-+-+-+-+
| | Padding | | | Padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 15: PARTICIPANT-PROVIDED-INFO format Figure 15: PARTICIPANT-PROVIDED-INFO format
Text: This field contains UTF-8 [6] encoded text. Text: This field contains UTF-8 [8] encoded text.
Padding: One, two, or three octets of padding added so that the Padding: One, two, or three octets of padding added so that the
contents of the PARTICIPANT-PROVIDED-INFO attribute is 32-bit contents of the PARTICIPANT-PROVIDED-INFO attribute is 32-bit
aligned. The Padding bits SHOULD be set to zero by the sender and aligned. The Padding bits MUST be set to zero by the sender and MUST
MUST be ignored by the receiver. If the attribute is already 32-bit be ignored by the receiver. If the attribute is already 32-bit
aligned, no padding is needed. aligned, no padding is needed.
5.2.9. STATUS-INFO 5.2.9. STATUS-INFO
The following is the format of the STATUS-INFO attribute. The following is the format of the STATUS-INFO attribute.
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 1 0 0 1|M| Length | | |0 0 0 1 0 0 1|M| Length | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| | | |
/ Text / / Text /
/ +-+-+-+-+-+-+-+-+ / +-+-+-+-+-+-+-+-+
| | Padding | | | Padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 16: STATUS-INFO format Figure 16: STATUS-INFO format
Text: This field contains UTF-8 [6] encoded text. Text: This field contains UTF-8 [8] encoded text.
In some situations, the contents of the Text field may be generated In some situations, the contents of the Text field may be generated
by an automaton. If this automaton has information about the by an automaton. If this automaton has information about the
preferred language of the receiver of a particular STATUS-INFO preferred language of the receiver of a particular STATUS-INFO
attribute, it MAY use this language to generate the Text field. attribute, it MAY use this language to generate the Text field.
Padding: One, two, or three octets of padding added so that the Padding: One, two, or three octets of padding added so that the
contents of the STATUS-INFO attribute is 32-bit aligned. The Padding contents of the STATUS-INFO attribute is 32-bit aligned. The Padding
bits SHOULD be set to zero by the sender and MUST be ignored by the bits MUST be set to zero by the sender and MUST be ignored by the
receiver. If the attribute is already 32-bit aligned, no padding is receiver. If the attribute is already 32-bit aligned, no padding is
needed. needed.
5.2.10. SUPPORTED-ATTRIBUTES 5.2.10. SUPPORTED-ATTRIBUTES
The following is the format of the SUPPORTED-ATTRIBUTES attribute. The following is the format of the SUPPORTED-ATTRIBUTES attribute.
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 28, line 30 skipping to change at page 28, line 30
Supp. Attr.: These fields contain the Types of the attributes that Supp. Attr.: These fields contain the Types of the attributes that
are supported by the floor control server in the following format: are supported by the floor control server in the following format:
R: Reserved: This bit MUST be set to zero upon transmission and MUST R: Reserved: This bit MUST be set to zero upon transmission and MUST
be ignored upon reception. be ignored upon reception.
Padding: One, two, or three octets of padding added so that the Padding: One, two, or three octets of padding added so that the
contents of the SUPPORTED-ATTRIBUTES attribute is 32-bit aligned. If contents of the SUPPORTED-ATTRIBUTES attribute is 32-bit aligned. If
the attribute is already 32-bit aligned, no padding is needed. the attribute is already 32-bit aligned, no padding is needed.
The Padding bits SHOULD be set to zero by the sender and MUST be The Padding bits MUST be set to zero by the sender and MUST be
ignored by the receiver. ignored by the receiver.
5.2.11. SUPPORTED-PRIMITIVES 5.2.11. SUPPORTED-PRIMITIVES
The following is the format of the SUPPORTED-PRIMITIVES attribute. The following is the format of the SUPPORTED-PRIMITIVES attribute.
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 1 0 1 1|M| Length | Primitive | Primitive | |0 0 0 1 0 1 1|M| Length | Primitive | Primitive |
skipping to change at page 29, line 13 skipping to change at page 29, line 13
Figure 18: SUPPORTED-PRIMITIVES format Figure 18: SUPPORTED-PRIMITIVES format
Primitive: These fields contain the types of the BFCP messages that Primitive: These fields contain the types of the BFCP messages that
are supported by the floor control server. See Table 1 for the list are supported by the floor control server. See Table 1 for the list
of BFCP primitives. of BFCP primitives.
Padding: One, two, or three octets of padding added so that the Padding: One, two, or three octets of padding added so that the
contents of the SUPPORTED-PRIMITIVES attribute is 32-bit aligned. If contents of the SUPPORTED-PRIMITIVES attribute is 32-bit aligned. If
the attribute is already 32-bit aligned, no padding is needed. the attribute is already 32-bit aligned, no padding is needed.
The Padding bits SHOULD be set to zero by the sender and MUST be The Padding bits MUST be set to zero by the sender and MUST be
ignored by the receiver. ignored by the receiver.
5.2.12. USER-DISPLAY-NAME 5.2.12. USER-DISPLAY-NAME
The following is the format of the USER-DISPLAY-NAME attribute. The following is the format of the USER-DISPLAY-NAME attribute.
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 1 1 0 0|M| Length | | |0 0 0 1 1 0 0|M| Length | |
skipping to change at page 29, line 37 skipping to change at page 29, line 37
/ +-+-+-+-+-+-+-+-+ / +-+-+-+-+-+-+-+-+
| | Padding | | | Padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 19: USER-DISPLAY-NAME format Figure 19: USER-DISPLAY-NAME format
Text: This field contains the UTF-8 encoded name of the user. Text: This field contains the UTF-8 encoded name of the user.
Padding: One, two, or three octets of padding added so that the Padding: One, two, or three octets of padding added so that the
contents of the USER-DISPLAY-NAME attribute is 32-bit aligned. The contents of the USER-DISPLAY-NAME attribute is 32-bit aligned. The
Padding bits SHOULD be set to zero by the sender and MUST be ignored Padding bits MUST be set to zero by the sender and MUST be ignored by
by the receiver. If the attribute is already 32-bit aligned, no the receiver. If the attribute is already 32-bit aligned, no padding
padding is needed. is needed.
5.2.13. USER-URI 5.2.13. USER-URI
The following is the format of the USER-URI attribute. The following is the format of the USER-URI attribute.
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 1 1 0 1|M| Length | | |0 0 0 1 1 0 1|M| Length | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
skipping to change at page 30, line 31 skipping to change at page 30, line 31
a conference set up by SIP, the USER-URI attribute would carry the a conference set up by SIP, the USER-URI attribute would carry the
SIP URI of the user. SIP URI of the user.
Messages containing a user's URI in a USER-URI attribute also Messages containing a user's URI in a USER-URI attribute also
contain the user's User ID. This way, a client receiving such a contain the user's User ID. This way, a client receiving such a
message can correlate the user's URI (e.g., the SIP URI the user message can correlate the user's URI (e.g., the SIP URI the user
used to join a conference) with the user's User ID. used to join a conference) with the user's User ID.
Padding: One, two, or three octets of padding added so that the Padding: One, two, or three octets of padding added so that the
contents of the USER-URI attribute is 32-bit aligned. The Padding contents of the USER-URI attribute is 32-bit aligned. The Padding
bits SHOULD be set to zero by the sender and MUST be ignored by the bits MUST be set to zero by the sender and MUST be ignored by the
receiver. If the attribute is already 32-bit aligned, no padding is receiver. If the attribute is already 32-bit aligned, no padding is
needed. needed.
5.2.14. BENEFICIARY-INFORMATION 5.2.14. BENEFICIARY-INFORMATION
The BENEFICIARY-INFORMATION attribute is a grouped attribute that The BENEFICIARY-INFORMATION attribute is a grouped attribute that
consists of a header, which is referred to as BENEFICIARY- consists of a header, which is referred to as BENEFICIARY-
INFORMATION-HEADER, followed by a sequence of attributes. The INFORMATION-HEADER, followed by a sequence of attributes. The
following is the format of the BENEFICIARY-INFORMATION-HEADER: following is the format of the BENEFICIARY-INFORMATION-HEADER:
skipping to change at page 31, line 5 skipping to change at page 31, line 5
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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 1 1 1 0|M| Length | Beneficiary ID | |0 0 0 1 1 1 0|M| Length | Beneficiary ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 21: BENEFICIARY-INFORMATION-HEADER format Figure 21: BENEFICIARY-INFORMATION-HEADER format
Beneficiary ID: This field contains a 16-bit value that uniquely Beneficiary ID: This field contains a 16-bit value that uniquely
identifies a user within a conference. identifies a user within a conference.
The following is the ABNF (Augmented Backus-Naur Form) [2] of the The following is the ABNF (Augmented Backus-Naur Form) [4] of the
BENEFICIARY-INFORMATION grouped attribute. (EXTENSION-ATTRIBUTE BENEFICIARY-INFORMATION grouped attribute. (EXTENSION-ATTRIBUTE
refers to extension attributes that may be defined in the future.) refers to extension attributes that may be defined in the future.)
BENEFICIARY-INFORMATION = (BENEFICIARY-INFORMATION-HEADER) BENEFICIARY-INFORMATION = (BENEFICIARY-INFORMATION-HEADER)
[USER-DISPLAY-NAME] [USER-DISPLAY-NAME]
[USER-URI] [USER-URI]
*(EXTENSION-ATTRIBUTE) *(EXTENSION-ATTRIBUTE)
Figure 22: BENEFICIARY-INFORMATION format Figure 22: BENEFICIARY-INFORMATION format
skipping to change at page 34, line 8 skipping to change at page 34, line 8
OVERALL-REQUEST-STATUS = (OVERALL-REQUEST-STATUS-HEADER) OVERALL-REQUEST-STATUS = (OVERALL-REQUEST-STATUS-HEADER)
[REQUEST-STATUS] [REQUEST-STATUS]
[STATUS-INFO] [STATUS-INFO]
*(EXTENSION-ATTRIBUTE) *(EXTENSION-ATTRIBUTE)
Figure 30: OVERALL-REQUEST-STATUS format Figure 30: OVERALL-REQUEST-STATUS format
5.3. Message Format 5.3. Message Format
This section contains the normative ABNF (Augmented Backus-Naur Form) This section contains the normative ABNF (Augmented Backus-Naur Form)
[2] of the BFCP messages. Extension attributes that may be defined [4] of the BFCP messages. Extension attributes that may be defined
in the future are referred to as EXTENSION-ATTRIBUTE in the ABNF. in the future are referred to as EXTENSION-ATTRIBUTE in the ABNF.
5.3.1. FloorRequest 5.3.1. FloorRequest
Floor participants request a floor by sending a FloorRequest message Floor participants request a floor by sending a FloorRequest message
to the floor control server. The following is the format of the to the floor control server. The following is the format of the
FloorRequest message: FloorRequest message:
FloorRequest = (COMMON-HEADER) FloorRequest = (COMMON-HEADER)
1*(FLOOR-ID) 1*(FLOOR-ID)
skipping to change at page 39, line 14 skipping to change at page 39, line 14
GoodbyeAck = (COMMON-HEADER) GoodbyeAck = (COMMON-HEADER)
*(EXTENSION-ATTRIBUTE) *(EXTENSION-ATTRIBUTE)
Figure 47: GoodbyeAck format Figure 47: GoodbyeAck format
6. Transport 6. Transport
The transport over which BFCP entities exchange messages depends on The transport over which BFCP entities exchange messages depends on
how clients obtain information to contact the floor control server how clients obtain information to contact the floor control server
(e.g., using an SDP offer/answer exchange [7] or the procedure (e.g., using an SDP offer/answer exchange [9] or the procedure
specified in [16]). Two transports are supported: TCP, appropriate specified in [3]). Two transports are supported: TCP, appropriate
where connectivity is not impeded by network elements such as NAT where connectivity is not impeded by network elements such as NAT
devices or media relays; and UDP for those deployments where TCP may devices or media relays; and UDP for those deployments where TCP may
not be applicable or appropriate. not be applicable or appropriate.
Informational note: In practice products are configured to try one
transport initially and use the other one as a fallback. Whether
TCP or UDP is chosen as underlying transport depends on type of
product and the nature of the environment it is deployed. Here
Appendix B are important to consider.
6.1. Reliable Transport 6.1. Reliable Transport
BFCP entities may elect to exchange BFCP messages using TCP BFCP entities may elect to exchange BFCP messages using TCP
connections. TCP provides an in-order reliable delivery of a stream connections. TCP provides an in-order reliable delivery of a stream
of bytes. Consequently, message framing needs to be implemented in of bytes. Consequently, message framing needs to be implemented in
the application layer. BFCP implements application-layer framing the application layer. BFCP implements application-layer framing
using TLV-encoded attributes. using TLV-encoded attributes.
A client MUST NOT use more than one TCP connection to communicate A client MUST NOT use more than one TCP connection to communicate
with a given floor control server within a conference. Nevertheless, with a given floor control server within a conference. Nevertheless,
skipping to change at page 40, line 30 skipping to change at page 40, line 36
being fragmented at the IP layer, the fragmentation of BFCP messages being fragmented at the IP layer, the fragmentation of BFCP messages
that exceed the path MTU size is performed at the BFCP level. that exceed the path MTU size is performed at the BFCP level.
Considerations related to fragmentation are covered in Section 6.2.3. Considerations related to fragmentation are covered in Section 6.2.3.
The message format for BFCP messages is the same regardless of The message format for BFCP messages is the same regardless of
whether the messages are sent in UDP datagrams or over a TCP stream. whether the messages are sent in UDP datagrams or over a TCP stream.
Clients MUST announce their presence to the floor control server by Clients MUST announce their presence to the floor control server by
sending a Hello message. The floor control server responds to the sending a Hello message. The floor control server responds to the
Hello message with a HelloAck message. The client considers the Hello message with a HelloAck message. The client considers the
floor control service as present and available only upon receiving floor control service as present and available only upon receiving
the HelloAck message. the HelloAck message. Situations where the floor control service is
considered to have become unavailable due to ICMP messages is
described in Section 6.2.2 and the behavior when timers fire is
described in Section 8.3.
As described in Section 8, each request sent by a floor participant As described in Section 8, each request sent by a floor participant
or chair shall form a client transaction that expects an or chair forms a client transaction that expects an acknowledgement
acknowledgement message back from the floor control server within a message back from the floor control server within a retransmission
retransmission window. Concordantly, messages sent by the floor window. Concordantly, messages sent by the floor control server that
control server that are not transaction-completing (e.g., FloorStatus initiate new transactions (e.g., FloorStatus announcements as part of
announcements as part of a FloorQuery subscription) are server- a FloorQuery subscription) require acknowledgement messages from the
initiated transactions that require acknowledgement messages from the
floor participant and chair entities to which they were sent. floor participant and chair entities to which they were sent.
If a Floor Control Server receives data that cannot be parsed, the If a Floor Control Server receives data that cannot be parsed, the
receiving server SHOULD send an Error message with parameter value 10 receiving server MUST send an Error message with parameter value 10
(Unable to parse message) indicating receipt of a malformed message. (Unable to parse message) indicating receipt of a malformed message,
given that it is possible to parse the received message to such an
extent that an Error message may be built.
Entities MUST have at most one outstanding request transaction at any Entities MUST have at most one outstanding request transaction per
one time. Implicit subscriptions occur for a client-initiated peer at any one time. Implicit subscriptions occur for a client-
request transaction whose acknowledgement is implied by the first initiated request transaction whose acknowledgement is implied by the
server-initiated response for that transaction, followed by zero of first server-initiated response for that transaction, followed by
more subsequent server-initiated messages corresponding to the same zero of more subsequent server-initiated messages corresponding to
transaction. An example is a FloorRequest message for which there the same transaction. An example is a FloorRequest message for which
are potentially multiple responses from the floor control server as there are potentially multiple responses from the floor control
it processes intermediate states until a terminal state (e.g., server as it processes intermediate states until a terminal state
Granted or Denied) is attained. The subsequent changes in state for (e.g., Granted or Denied) is attained. The subsequent changes in
the request are new transactions whose Transaction ID is determined state for the request are new transactions whose Transaction ID is
by the floor control server and whose receipt by the client determined by the floor control server and whose receipt by the
participant shall be acknowledged with a FloorRequestStatusAck client participant is acknowledged with a FloorRequestStatusAck
message. message.
By restricting entities to having at most one pending transaction By restricting entities to having at most one pending transaction
open in a BFCP connection, both the out-of-order receipt of messages open in a BFCP connection, both the out-of-order receipt of messages
as well as the possibility for congestion are mitigated. Additional as well as the possibility for congestion are mitigated. Additional
details regarding congestion control are provided in Section 6.2.1. details regarding congestion control are provided in Section 6.2.1.
A server-initiated request (e.g., a FloorStatus with an update from A server-initiated request (e.g., a FloorStatus with an update from
the floor control server) received by a participant before the the floor control server) received by a participant before the
initial FloorRequestStatus message that closes the client-initiated initial FloorRequestStatus message that closes the client-initiated
transaction that was instigated by the FloorRequest MUST be treated transaction that was instigated by the FloorRequest MUST be treated
as superseding the information conveyed in any such late arriving as superseding the information conveyed in any such late arriving
response. As the floor control server cannot send a second update to response. As the floor control server cannot send a second update to
the implicit floor status subscription until the first is the implicit floor status subscription until the first is
acknowledged, ordinality is maintained. acknowledged, ordinality is maintained.
If a client wishes to end its BFCP connection with a floor control If a client wishes to end its BFCP connection with a floor control
server, it is RECOMMENDED that the client send a Goodbye message to server, it is REQUIRED that the client send a Goodbye message to
dissociate itself from any allocated resources. If a floor control dissociate itself from any allocated resources. If a floor control
server wishes to end its BFCP connection with a client (e.g., the server wishes to end its BFCP connection with a client (e.g., the
Focus of the conference informs the floor control server that the Focus of the conference informs the floor control server that the
client has been kicked out from the conference), it is RECOMMENDED client has been kicked out from the conference), it is REQUIRED that
that the floor control server send a Goodbye message towards the the floor control server send a Goodbye message towards the client.
client.
RFC 5018 [16] specifies how to establish a TCP connection to a floor RFC 5018 [3] specifies how to establish a TCP connection to a floor
control server outside the context of an offer/answer exchange. When control server outside the context of an offer/answer exchange. When
using UDP the same set of data is needed for a BFCP connection as using UDP the same set of data is needed for a BFCP connection as
listed in [16], Section 3, i.e. transport address of the server, the listed in [3], Section 3, i.e. transport address of the server, the
conference identifier, and the user identifier. The procedures and conference identifier, and the user identifier. The procedures and
considerations for resolving a host name into an IP address also considerations for resolving a host name into an IP address also
applies to BFCP over an unreliable transport. In [16], Section 4 applies to BFCP over an unreliable transport. In [3], Section 4
applies, but when using BFCP over an unreliable transport the floor applies, but when using BFCP over an unreliable transport the floor
control server that receives a BFCP message over UDP (no DTLS) SHOULD control server that receives a BFCP message over UDP (no DTLS) SHOULD
request the use of DTLS by generating an Error message with an Error request the use of DTLS by generating an Error message with an Error
code with a value of 11 (Use DTLS). The recommendations for code with a value of 11 (Use DTLS). A floor control server that is
authentication in [16], Section 5 and the security considerations in configured to require DTLS MUST request the use of DTLS this way.
Section 6 also apply when an unreliable transport is used, both for The recommendations for authentication in [3], Section 5 and the
certificate-based server authentication and for client authentication security considerations in [3], Section 6 also apply when an
based on a pre-shared secret. unreliable transport is used, both for certificate-based server
authentication and for client authentication based on a pre-shared
secret.
6.2.1. Congestion Control 6.2.1. Congestion Control
BFCP may be characterized to generate "low data-volume" traffic, per BFCP may be characterized to generate "low data-volume" traffic, per
the classification in [24]. Nevertheless is it necessary to ensure the classification in [25]. Nevertheless is it necessary to ensure
suitable and necessary congestion control mechanisms are used for suitable and necessary congestion control mechanisms are used for
BFCP over UDP. As described in previous paragraph, within the same BFCP over UDP. As described in Section 6.2, within the same BFCP
BFCP connection, every entity - client or server - is only allowed to connection, every entity - client or server - is only allowed to send
send one request at a time, and await the acknowledging response. one request at a time, and await the acknowledging response. This
This way at most one datagram is sent per RTT given the message is way at most one datagram is sent per RTT given the message is not
not lost during transmission. In case the message is lost, the lost during transmission. In case the message is lost, the request
request retransmission timer T1 specified in Section 8.3.1 will fire retransmission timer T1 specified in Section 8.3.1 will fire and the
and the message is retransmitted up to three times, in addition to message is retransmitted up to three times, in addition to the
the original transmission of the message. The default initial original transmission of the message. The default initial interval
interval is set to 500ms and the interval is doubled after each MUST be set to 500ms and the interval MUST be doubled after each
retransmission attempt. This is identical to the specification of retransmission attempt. This is identical to the specification of
the timer A and its initial value T1 in SIP as described in Section the timer A and its initial value T1 in SIP as described in Section
17.1.1.2 of [14]. 17.1.1.2 of [16].
6.2.2. ICMP Error Handling 6.2.2. ICMP Error Handling
If a BFCP entity receives an ICMP port unreachable message mid- If a BFCP entity receives an ICMP port unreachable message mid-
connection, the entity SHOULD treat the BFCP connection as closed connection, the entity MUST treat the BFCP connection as closed
(e.g., an implicit Goodbye message from the peer). The entity MAY (e.g., an implicit Goodbye message from the peer). The entity MAY
attempt to re-establish the BFCP connection afresh. The new BFCP attempt to re-establish the BFCP connection afresh. The new BFCP
connection will appear as originating from a wholly new floor connection will appear as originating from a wholly new floor
participant, chair or floor control server with all state previously participant, chair or floor control server with all state previously
held about that participant lost. held about that participant lost.
Informational note: The recommendation to treat the connection as Informational note: The recommendation to treat the connection as
closed in this case, stems from the fact that the peer entities closed in this case, stems from the fact that the peer entities
cannot rely on IP and port tuple to uniquely identify the cannot rely on IP and port tuple to uniquely identify the
participant, nor would extending Hello to include an attribute participant, nor would extending Hello to include an attribute
that advertised what identity the entity previously was assigned that advertised what identity the entity previously was assigned
(i.e., a User ID) be acceptable due to session hijacking. (i.e., a User ID) be acceptable due to session hijacking.
In deployments where NAT appliances or other such devices are present In deployments where NAT appliances or other such devices are present
and affecting port reachability for each entity, one possibility is and affecting port reachability for each entity, one possibility is
to utilize the peer connectivity checks, relay use and NAT pinhole to utilize the peer connectivity checks, relay use and NAT pinhole
maintenance mechanisms defined in ICE [13]. maintenance mechanisms defined in ICE [15].
6.2.3. Fragmentation Handling 6.2.3. Fragmentation Handling
When using UDP, a single BFCP message could be fragmented at the IP When using UDP, a single BFCP message could be fragmented at the IP
layer if its overall size exceeds the path MTU of the network. To layer if its overall size exceeds the path MTU of the network. To
avoid this happening at the IP layer, a fragmentation scheme for BFCP avoid this happening at the IP layer, a fragmentation scheme for BFCP
is defined below. is defined below.
BFCP is designed for achieving small message size, due to the binary BFCP is designed for achieving small message size, due to the binary
encoding as described in Section 1. The fragmentation scheme is encoding as described in Section 1. The fragmentation scheme is
therefore deliberately kept simple and straightforward, since the therefore deliberately kept simple and straightforward, since the
probability of fragmentation of BFCP messages being required is probability of fragmentation of BFCP messages being required is
small. By design, the fragmentation scheme does not acknowledge small. By design, the fragmentation scheme does not acknowledge
individual BFCP message fragments. The whole BFCP message is individual BFCP message fragments. The whole BFCP message is
acknowledged if received completely. acknowledged if received completely.
BFCP entities should consider the MTU size available between the BFCP entities should consider the MTU size available between the
sender and the receiver and MAY run MTU discovery, such as sender and the receiver and MAY run MTU discovery, such as
[19][20][21], for this purpose. [20][21][22], for this purpose.
When transmitting a BFCP message with size greater than the path MTU, When transmitting a BFCP message with size greater than the path MTU,
the sender MUST fragment the message into a series of N contiguous the sender MUST fragment the message into a series of N contiguous
data ranges. The sender then creates N BFCP fragment messages (one data ranges. The value for N is defined as ceil(message size / MTU
for each data range) with the same Transaction ID. The size of each size), where ceil is the integer ceiling function. The sender then
of these N messages MUST be smaller than the path MTU. The F flag in creates N BFCP fragment messages (one for each data range) with the
the COMMON-HEADER is set to indicate fragmentation of the BFCP same Transaction ID. The size of each of these N messages MUST be
message. smaller than the path MTU. The F flag in the COMMON-HEADER is set to
indicate fragmentation of the BFCP message.
For each of these fragments the Fragment Offset and Fragment Length For each of these fragments the Fragment Offset and Fragment Length
fields are included in the COMMON-HEADER. The Fragment Offset field fields are included in the COMMON-HEADER. The Fragment Offset field
denotes the number of bytes contained in the previous fragments. The denotes the number of bytes contained in the previous fragments. The
Fragment Length contains the length of the fragment itself. Note Fragment Length contains the length of the fragment itself. Note
that the Payload Length field contains the length of the entire, that the Payload Length field contains the length of the entire,
unfragmented message. unfragmented message.
When a BFCP implementation receives a BFCP message fragment, it MUST When a BFCP implementation receives a BFCP message fragment, it MUST
buffer the fragment until it has received the entire BFCP message. buffer the fragment until either it has received the entire BFCP
The state machine should handle the BFCP message only after all the message, or until the Response Retransmission Timer expires. The
state machine should handle the BFCP message only after all the
fragments for the message have been received. fragments for the message have been received.
If a fragment of a BFCP message is lost, the sender will not receive If a fragment of a BFCP message is lost, the sender will not receive
an acknowledgement for the message. Therefore the sender will an acknowledgement for the message. Therefore the sender will
retransmit the message with same transaction ID as specified in retransmit the message with same transaction ID as specified in
Section 8.3. If the acknowledgement message sent by the receiver is Section 8.3. If the acknowledgement message sent by the receiver is
lost, then the entire message will be resent by the sender. The lost, then the entire message will be resent by the sender. The
receiver must then retransmit the acknowledgement. The receiver MAY receiver MUST then retransmit the acknowledgement. The receiver MAY
discard an incomplete buffer utilizing the Response Retransmission discard an incomplete buffer utilizing the Response Retransmission
Timer, starting the timer after the receipt of the first fragment. Timer, starting the timer after the receipt of the first fragment.
A Denial of Service (DoS) attack utilizing the fragmentation A Denial of Service (DoS) attack utilizing the fragmentation
scheme described above is mitigated by the fact that the Response scheme described above is mitigated by the fact that the Response
Retransmission Timer is started after receipt of the first BFCP Retransmission Timer is started after receipt of the first BFCP
message fragment. In addition, the Payload Length field may be message fragment. In addition, the Payload Length field can be
compared with the Fragment Offset and Fragment Length fields to compared with the Fragment Offset and Fragment Length fields to
verify the message fragments as they arrive. To make DoS attacks verify the message fragments as they arrive. To make DoS attacks
with spoofed IP addresses difficult, BFCP entities should use the with spoofed IP addresses difficult, BFCP entities SHOULD use the
cookie exchange mechanism in DTLS [5]. cookie exchange mechanism in DTLS [7].
When deciding message fragment size based on path MTU, the BFCP When deciding message fragment size based on path MTU, the BFCP
fragmentation handling should take into account how the DTLS record fragmentation handling should take into account how the DTLS record
framing expands the datagram size as described in Section 4.1.1.1 of framing expands the datagram size as described in Section 4.1.1.1 of
[5]. [7].
6.2.4. NAT Traversal 6.2.4. NAT Traversal
One of the key benefits when using UDP for BFCP communication is the One of the key benefits when using UDP for BFCP communication is the
ability to leverage the existing NAT traversal infrastructure and ability to leverage the existing NAT traversal infrastructure and
strategies deployed to facilitate transport of the media associated strategies deployed to facilitate transport of the media associated
with the video conferencing sessions. Depending on the given with the video conferencing sessions. Depending on the given
deployment, this infrastructure typically includes some subset of ICE deployment, this infrastructure typically includes some subset of ICE
[13]. [15].
In order to facilitate the initial establishment of NAT bindings, and In order to facilitate the initial establishment of NAT bindings, and
to maintain those bindings once established, BFCP entities using an to maintain those bindings once established, BFCP entities using an
unreliable transport are RECOMMENDED to use STUN [9] Binding unreliable transport are RECOMMENDED to use STUN [11] Binding
Indication for keep-alives, as described for ICE [13]. [22], Section Indication for keep-alives, as described for ICE [15]. [23], Section
6.7 provides useful recommendations for middlebox interaction when 6.7 provides useful recommendations for middlebox interaction when
DTLS is used. DTLS is used.
Informational note: Since the version number is set to 2 when BFCP Informational note: Since the version number is set to 2 when BFCP
is used over an unreliable transport, cf. the Ver field in is used over an unreliable transport, cf. the Ver field in
Section 5.1, it is straight forward to distinguish between STUN Section 5.1, it is straight forward to distinguish between STUN
and BFCP packets even without checking the STUN magic cookie [9]. and BFCP packets even without checking the STUN magic cookie [11].
In order to facilitate traversal of BFCP packets through NATs, BFCP In order to facilitate traversal of BFCP packets through NATs, BFCP
entities using an unreliable transport are RECOMMENDED to use entities using an unreliable transport are RECOMMENDED to use
symmetric ports for sending and receiving BFCP packets, as symmetric ports for sending and receiving BFCP packets, as
recommended for RTP/RTCP [8]. recommended for RTP/RTCP [10].
7. Lower-Layer Security 7. Lower-Layer Security
BFCP relies on lower-layer security mechanisms to provide replay and BFCP relies on lower-layer security mechanisms to provide replay and
integrity protection and confidentiality. BFCP floor control servers integrity protection and confidentiality. BFCP floor control servers
and clients (which include both floor participants and floor chairs) and clients (which include both floor participants and floor chairs)
MUST support TLS for transport over TCP [4] and MUST support DTLS [5] MUST support TLS for transport over TCP [6] and MUST support DTLS [7]
for transport over UDP. Any BFCP entity MAY support other security for transport over UDP. Any BFCP entity MAY support other security
mechanisms. mechanisms.
BFCP entities MUST support, at a minimum, the BFCP entities MUST support, at a minimum, the
TLS_RSA_WITH_AES_128_CBC_SHA ciphersuite [4]. TLS_RSA_WITH_AES_128_CBC_SHA ciphersuite [6].
Which party, the client or the floor control server, acts as the TLS/ Which party, the client or the floor control server, acts as the TLS/
DTLS server depends on how the underlying TLS/DTLS connection is DTLS server depends on how the underlying TLS/DTLS connection is
established. For a TCP/TLS connection established using an SDP established. For a TCP/TLS connection established using an SDP
offer/answer exchange [7], the answerer (which may be the client or offer/answer exchange [9], the answerer (which may be the client or
the floor control server) always acts as the TLS server. For a UDP/ the floor control server) always acts as the TLS server. If the TCP
DTLS connection established using the same exchange, either party can connection is lost, the active endpoint, i.e., the current TLS
be the DTLS server depending on the setup attributes exchanged; client, is responsible for re-establishing the TCP connection.
examples can be found in [22]. Unless a new TLS session is negotiated, subsequent SDP offers and
answers will not impact the previously negotiated TLS roles.
For a UDP/DTLS connection established using the an SDP offer/answer
exchange, either party can be the DTLS server depending on the setup
attributes exchanged; examples can be found in [23].
8. Protocol Transactions 8. Protocol Transactions
In BFCP, there are two types of transactions: client-initiated In BFCP, there are two types of transactions: client-initiated
transactions and server-initiated transactions. transactions and server-initiated transactions.
Client-initiated transactions consist of a request from a client to a Client-initiated transactions consist of a request from a client to a
floor control server and a response from the floor control server to floor control server and a response from the floor control server to
the client. The request carries a Transaction ID in its common the client. The request carries a Transaction ID in its common
header, which the floor control server copies into the response. header, which the floor control server copies into the response.
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behavior depending on underlying transport: behavior depending on underlying transport:
When using a reliable transport, server-initiated transactions When using a reliable transport, server-initiated transactions
consist of a single message from a floor control server to a consist of a single message from a floor control server to a
client (notifications). Since they do not trigger any response, client (notifications). Since they do not trigger any response,
their Transaction ID is set to 0. their Transaction ID is set to 0.
When using an unreliable transport, server-initiated transactions When using an unreliable transport, server-initiated transactions
consist of a request from a floor control server to a client and a consist of a request from a floor control server to a client and a
response from the client to the floor control server. The response from the client to the floor control server. The
Transaction ID must be non-zero and unique in the context of Transaction ID MUST be non-zero and unique in the context of
outstanding transactions over an unreliable transport. The outstanding transactions over an unreliable transport. The
request carries a Transaction ID in its common header, which the request carries a Transaction ID in its common header, which the
client copies into the response. Floor control servers use client copies into the response. Floor control servers use
Transaction ID values to match responses with previously issued Transaction ID values to match responses with previously issued
requests. requests.
When using BFCP over an unreliable transport, it is important that When using BFCP over an unreliable transport, it is important that
the initiator of a transaction choose a Transaction ID value that the initiator of a transaction choose a Transaction ID value that
lets the receiver distinguish the reception of the next message in a lets the receiver distinguish the reception of the next message in a
sequence of BFCP messages from a retransmission of a previous sequence of BFCP messages from a retransmission of a previous
message. Therefore, BFCP entities using an unreliable transport message. Therefore, BFCP entities using an unreliable transport MUST
SHOULD use monotonically increasing Transaction ID values. use monotonically increasing Transaction ID values (except for wrap-
around).
When using BFCP over an unreliable transport, all requests will use When using BFCP over an unreliable transport, all requests will use
retransmission timer T1 (see Section 8.3) until the transaction is retransmission timer T1 (see Section 8.3) until the transaction is
completed. completed.
8.1. Client Behavior 8.1. Client Behavior
A client starting a client-initiated transaction MUST set the A client starting a client-initiated transaction MUST set the
Conference ID in the common header of the message to the Conference Conference ID in the common header of the message to the Conference
ID for the conference that the client obtained previously. ID for the conference that the client obtained previously.
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A floor control server sending a response within a client-initiated A floor control server sending a response within a client-initiated
transaction MUST copy the Conference ID, the Transaction ID, and the transaction MUST copy the Conference ID, the Transaction ID, and the
User ID from the request received from the client into the response. User ID from the request received from the client into the response.
Server-initiated transactions MUST contain a Transaction ID equal to Server-initiated transactions MUST contain a Transaction ID equal to
0 when BFCP is used over a reliable transport. Over an unreliable 0 when BFCP is used over a reliable transport. Over an unreliable
transport, the Transaction ID shall have the same properties as for transport, the Transaction ID shall have the same properties as for
client-initiated transactions: the server MUST set the Transaction ID client-initiated transactions: the server MUST set the Transaction ID
value in the common header to a number that is different from 0 and 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 that MUST NOT be reused, i.e. monotonically increasing valuse as
appropriate response from the client is received for the transaction. defined in Section 8. The server uses the Transaction ID value to
The server uses the Transaction ID value to match this message with match this message with the response from the floor participant or
the response from the floor participant or floor chair. floor chair.
8.3. Timers 8.3. Timers
When BFCP entities are communicating over an unreliable transport, When BFCP entities are communicating over an unreliable transport,
two retransmission timers are employed to help mitigate against loss two retransmission timers are employed to help mitigate against loss
of datagrams. Retransmission and response caching are not required of datagrams. Retransmission and response caching are not required
when BFCP entities communicate over a reliable transport. when BFCP entities communicate over a reliable transport.
8.3.1. Request Retransmission Timer, T1 8.3.1. Request Retransmission Timer, T1
T1 is a timer that schedules retransmission of a request until an T1 is a timer that schedules retransmission of a request until an
appropriate response is received or until the maximum number of appropriate response is received or until the maximum number of
retransmissions have occurred. The timer doubles on each re- retransmissions have occurred. The timer doubles on each re-
transmit, failing after three unacknowledged retransmission attempts. transmit, failing after three unacknowledged retransmission attempts.
If a valid response is not received for a client- or server-initiated If a valid response is not received for a client- or server-initiated
transaction, the implementation MUST consider the BFCP connection as transaction, the implementation MUST consider the BFCP connection as
failed. Implementations SHOULD follow the reestablishment procedure failed. Implementations SHOULD follow the reestablishment procedure
described in section 6 (e.g., initiate a new offer/answer [10] described in section 6 (e.g., initiate a new offer/answer [12]
exchange). exchange).
8.3.2. Response Retransmission Timer, T2 8.3.2. Response Retransmission Timer, T2
T2 is a timer that, when fires, signals that the BFCP entity can T2 is a timer that, when fires, signals that the BFCP entity can
release knowledge of the transaction against which it is running. It release knowledge of the transaction against which it is running. It
is started upon the first transmission of the response to a request 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 and is the only mechanism by which that response is released by the
BFCP entity. Any subsequent retransmissions of the same request can BFCP entity. Any subsequent retransmissions of the same request can
be responded to by replaying the cached response, whilst that value be responded to by replaying the cached response, whilst that value
is retained until the timer has fired. is retained until the timer has fired. Refer to Section 6.2.3 for
the role this timer has in the fragmentation handling scheme.
8.3.3. Timer Values 8.3.3. Timer Values
The table below defines the different timers required when BFCP The table below defines the different timers required when BFCP
entities communicate over an unreliable transport. entities communicate over an unreliable transport.
+-------+--------------------------------------+---------+ +-------+--------------------------------------+---------+
| Timer | Description | Value/s | | Timer | Description | Value/s |
+-------+--------------------------------------+---------+ +-------+--------------------------------------+---------+
| T1 | Initial request retransmission timer | 0.5s | | T1 | Initial request retransmission timer | 0.5s |
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the floor control server checks whether the client sending the the floor control server checks whether the client sending the
message is authorized. If the client is not authorized to perform message is authorized. If the client is not authorized to perform
the operation being requested, the floor control server generates an the operation being requested, the floor control server generates an
Error message, as described in Section 13.8, with an Error code with Error message, as described in Section 13.8, with an Error code with
a value of 5 (Unauthorized Operation). Messages from a client that a value of 5 (Unauthorized Operation). Messages from a client that
cannot be authorized MUST NOT be processed further. cannot be authorized MUST NOT be processed further.
9.1. TLS/DTLS Based Mutual Authentication 9.1. TLS/DTLS Based Mutual Authentication
BFCP supports TLS/DTLS based mutual authentication between clients BFCP supports TLS/DTLS based mutual authentication between clients
and floor control servers. BFCP assumes that there is an integrity- and floor control servers. If TLS/DTLS is used, an initial
protected channel between the client and the floor control server integrity-protected channel is REQUIRED between the client and the
that can be used to exchange their self-signed certificates or, more floor control server that can be used to exchange their self-signed
commonly, the fingerprints of these certificates. These certificates certificates or, more commonly, the fingerprints of these
are used at TLS/DTLS establishment time. certificates. These certificates are used at TLS/DTLS establishment
time.
The implementation of such an integrity-protected channel using The implementation of such an integrity-protected channel using
SIP and the SDP offer/answer model is described in [7]. SIP and the SDP offer/answer model is described in [9].
BFCP messages received over an authenticated TLS/DTLS connection are BFCP messages received over an authenticated TLS/DTLS connection are
considered authenticated. A floor control server that receives a considered authenticated. A floor control server that receives a
BFCP message over TCP/UDP (no TLS/DTLS) can request the use of TLS/ BFCP message over TCP/UDP (no TLS/DTLS) MAY request the use of TLS/
DTLS by generating an Error message, as described in Section 13.8, DTLS by generating an Error message, as described in Section 13.8,
with an Error code with a value of 9 (Use TLS) or a value of 11 (Use with an Error code with a value of 9 (Use TLS) or a value of 11 (Use
DTLS) respectively. Clients SHOULD simply ignore unauthenticated DTLS) respectively. Clients configured to require the use of TLS/
messages. DTLS MUST ignore unauthenticated messages.
Note that future extensions may define additional authentication Note that future extensions may define additional authentication
mechanisms that may not require an initial integrity-protected mechanisms that may not require an initial integrity-protected
channel (e.g., authentication based on certificates signed by a channel (e.g., authentication based on certificates signed by a
certificate authority). certificate authority).
As described in Section 9, floor control servers need to perform As described in Section 9, floor control servers need to perform
authorization before processing any message. In particular, the authorization before processing any message. In particular, the
floor control server SHOULD check that messages arriving over a given floor control server MUST check that messages arriving over a given
authenticated TLS/DTLS connection use an authorized User ID (i.e., a authenticated TLS/DTLS connection use an authorized User ID (i.e., a
User ID that the user that established the authenticated TLS/DTLS User ID that the user that established the authenticated TLS/DTLS
connection is allowed to use). connection is allowed to use).
10. Floor Participant Operations 10. Floor Participant Operations
This section specifies how floor participants can perform different This section specifies how floor participants can perform different
operations, such as requesting a floor, using the protocol elements operations, such as requesting a floor, using the protocol elements
described in earlier sections. Section 11 specifies operations that described in earlier sections. Section 11 specifies operations that
are specific to floor chairs, such as instructing the floor control are specific to floor chairs, such as instructing the floor control
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not the participant that would eventually get the floor (i.e., a not the participant that would eventually get the floor (i.e., a
third-party floor request), the sender SHOULD add a BENEFICIARY-ID third-party floor request), the sender SHOULD add a BENEFICIARY-ID
attribute to the message identifying the beneficiary of the floor. attribute to the message identifying the beneficiary of the floor.
Note that the name space for both the User ID and the Beneficiary Note that the name space for both the User ID and the Beneficiary
ID is the same. That is, a given participant is identified by a ID is the same. That is, a given participant is identified by a
single 16-bit value that can be used in the User ID in the common single 16-bit value that can be used in the User ID in the common
header and in several attributes: BENEFICIARY-ID, BENEFICIARY- header and in several attributes: BENEFICIARY-ID, BENEFICIARY-
INFORMATION, and REQUESTED-BY-INFORMATION. INFORMATION, and REQUESTED-BY-INFORMATION.
The floor participant must insert at least one FLOOR-ID attribute in The floor participant MUST insert at least one FLOOR-ID attribute in
the FloorRequest message. If the client inserts more than one the FloorRequest message. If the client inserts more than one
FLOOR-ID attribute, the floor control server will treat all the floor FLOOR-ID attribute, the floor control server will treat all the floor
requests as an atomic package. That is, the floor control server requests as an atomic package. That is, the floor control server
will either grant or deny all the floors in the FloorRequest message. will either grant or deny all the floors in the FloorRequest message.
The floor participant may use a PARTICIPANT-PROVIDED-INFO attribute The floor participant may use a PARTICIPANT-PROVIDED-INFO attribute
to state the reason why the floor or floors are being requested. The to state the reason why the floor or floors are being requested. The
Text field in the PARTICIPANT-PROVIDED-INFO attribute is intended for Text field in the PARTICIPANT-PROVIDED-INFO attribute is intended for
human consumption. human consumption.
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overall status of the floor request. If the Request Status value is overall status of the floor request. If the Request Status value is
Granted, all the floors that were requested in the FloorRequest Granted, all the floors that were requested in the FloorRequest
message have been granted. If the Request Status value is Denied, message have been granted. If the Request Status value is Denied,
all the floors that were requested in the FloorRequest message have all the floors that were requested in the FloorRequest message have
been denied. A floor request is considered to be ongoing while it is been denied. A floor request is considered to be ongoing while it is
in the Pending, Accepted, or Granted states. If the floor request in the Pending, Accepted, or Granted states. If the floor request
value is unknown, then the response is still processed. However, no value is unknown, then the response is still processed. However, no
meaningful value can be reported to the user. meaningful value can be reported to the user.
The STATUS-INFO attribute, if present, provides extra information The STATUS-INFO attribute, if present, provides extra information
that the floor participant MAY display to the user. that the floor participant can display to the user.
The FLOOR-REQUEST-STATUS attributes provide information about the The FLOOR-REQUEST-STATUS attributes provide information about the
status of the floor request as it relates to a particular floor. The status of the floor request as it relates to a particular floor. The
STATUS-INFO attribute, if present, provides extra information that STATUS-INFO attribute, if present, provides extra information that
the floor participant MAY display to the user. the floor participant can display to the user.
The BENEFICIARY-INFORMATION attribute identifies the beneficiary of The BENEFICIARY-INFORMATION attribute identifies the beneficiary of
the floor request in third-party floor requests. The REQUESTED-BY- the floor request in third-party floor requests. The REQUESTED-BY-
INFORMATION attribute need not be present in FloorRequestStatus INFORMATION attribute need not be present in FloorRequestStatus
messages received by the floor participant that requested the floor, messages received by the floor participant that requested the floor,
as this floor participant is already identified by the User ID in the as this floor participant is already identified by the User ID in the
common header. common header.
The PRIORITY attribute, when present, contains the priority that was The PRIORITY attribute, when present, contains the priority that was
requested by the generator of the FloorRequest message. requested by the generator of the FloorRequest message.
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floor control server will grant the floor request as a whole. On the floor control server will grant the floor request as a whole. On the
other hand, if one of the floor chairs denies its floor, the floor other hand, if one of the floor chairs denies its floor, the floor
control server will deny the floor request as a whole, regardless of control server will deny the floor request as a whole, regardless of
the other floor chair's decision. the other floor chair's decision.
The floor chair provides the new status of the floor request as it The floor chair provides the new status of the floor request as it
relates to a particular floor using a FLOOR-REQUEST-STATUS attribute. relates to a particular floor using a FLOOR-REQUEST-STATUS attribute.
If the new status of the floor request is Accepted, the floor chair If the new status of the floor request is Accepted, the floor chair
MAY use the Queue Position field to provide a queue position for the MAY use the Queue Position field to provide a queue position for the
floor request. If the floor chair does not wish to provide a queue floor request. If the floor chair does not wish to provide a queue
position, all the bits of the Queue Position field SHOULD be set to position, all the bits of the Queue Position field MUST be set to
zero. The floor chair SHOULD use the Status Revoked to revoke a zero. The floor chair MUST use the Status Revoked to revoke a floor
floor that was granted (i.e., Granted status) and SHOULD use the that was granted (i.e., Granted status) and MUST use the Status
Status Denied to reject floor requests in any other status (e.g., Denied to reject floor requests in any other status (e.g., Pending
Pending and Accepted). and Accepted).
The floor chair MAY add an OVERALL-REQUEST-STATUS attribute to the The floor chair MAY add an OVERALL-REQUEST-STATUS attribute to the
ChairAction message to provide a new overall status for the floor ChairAction message to provide a new overall status for the floor
request. If the new overall status of the floor request is Accepted, request. If the new overall status of the floor request is Accepted,
the floor chair MAY use the Queue Position field to provide a queue the floor chair can use the Queue Position field to provide a queue
position for the floor request. position for the floor request.
Note that a particular floor control server may implement a Note that a particular floor control server can implement a
different queue for each floor containing all the floor requests different queue for each floor containing all the floor requests
that relate to that particular floor, a general queue for all that relate to that particular floor, a general queue for all
floor requests, or both. Also note that a floor request may floor requests, or both. Also note that a floor request can
involve several floors and that a ChairAction message may only involve several floors and that a ChairAction message can only
deal with a subset of these floors (e.g., if a single floor chair deal with a subset of these floors (e.g., if a single floor chair
is not authorized to manage all the floors). In this case, the is not authorized to manage all the floors). In this case, the
floor control server will combine the instructions received from floor control server will combine the instructions received from
the different floor chairs in FLOOR-REQUEST-STATUS attributes to the different floor chairs in FLOOR-REQUEST-STATUS attributes to
come up with the overall status of the floor request. come up with the overall status of the floor request.
Note that, while the action of a floor chair may communicate Note that, while the action of a floor chair may communicate
information in the OVERALL-REQUEST-STATUS attribute, the floor information in the OVERALL-REQUEST-STATUS attribute, the floor
control server may override, modify, or ignore this field's control server may override, modify, or ignore this field's
content. content.
The floor chair may use STATUS-INFO attributes to state the reason The floor chair MAY include STATUS-INFO attributes to state the
why the floor or floors are being accepted, granted, or revoked. The reason why the floor or floors are being accepted, granted, or
Text in the STATUS-INFO attribute is intended for human consumption. revoked. The Text in the STATUS-INFO attribute is intended for human
consumption.
11.2. Receiving a Response 11.2. Receiving a Response
A message from the floor control server is considered a response to A message from the floor control server is considered a response to
the ChairAction message if the message from the server has the same the ChairAction message if the message from the server has the same
Conference ID, Transaction ID, and User ID as the ChairAction Conference ID, Transaction ID, and User ID as the ChairAction
message, as described in Section 8.1. On receiving such a response, message, as described in Section 8.1. On receiving such a response,
the floor chair follows the rules in Section 9 that relate to floor the floor chair follows the rules in Section 9 that relate to floor
control server authentication. control server authentication.
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12.1.2. Receiving a Response 12.1.2. Receiving a Response
A message from the floor control server is considered a response to A message from the floor control server is considered a response to
the FloorQuery message if the message from the floor control server the FloorQuery message if the message from the floor control server
has the same Conference ID, Transaction ID, and User ID as the has the same Conference ID, Transaction ID, and User ID as the
FloorRequest message, as described in Section 8.1. On receiving such FloorRequest message, as described in Section 8.1. On receiving such
a response, the client follows the rules in Section 9 that relate to a response, the client follows the rules in Section 9 that relate to
floor control server authentication. floor control server authentication.
On reception of the FloorQuery message, the floor control server will On reception of the FloorQuery message, the floor control server MUST
respond with a FloorStatus message or with an Error message. If the respond with a FloorStatus message or with an Error message. If the
response is a FloorStatus message, it will contain information about response is a FloorStatus message, it will contain information about
one of the floors the client requested information about. If the one of the floors the client requested information about. If the
client did not include any FLOOR-ID attribute in its FloorQuery client did not include any FLOOR-ID attribute in its FloorQuery
message (i.e., the client does not want to receive information about message (i.e., the client does not want to receive information about
any floor any longer), the FloorStatus message from the floor control any floor any longer), the FloorStatus message from the floor control
server will not include any FLOOR-ID attribute either. server will not include any FLOOR-ID attribute either.
FloorStatus messages that carry information about a floor contain a FloorStatus messages that carry information about a floor contain a
FLOOR-ID attribute that identifies the floor. After this attribute, FLOOR-ID attribute that identifies the floor. After this attribute,
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FloorRequestQuery message can contain. In addition, the ABNF FloorRequestQuery message can contain. In addition, the ABNF
specifies normatively which of these attributes are mandatory, and specifies normatively which of these attributes are mandatory, and
which ones are optional. which ones are optional.
The client sets the Conference ID and the Transaction ID in the The client sets the Conference ID and the Transaction ID in the
common header following the rules given in Section 8.1. The client common header following the rules given in Section 8.1. The client
sets the User ID in the common header to the client's identifier. sets the User ID in the common header to the client's identifier.
This User ID will be used by the floor control server to authenticate This User ID will be used by the floor control server to authenticate
and authorize the request. and authorize the request.
The client must insert a FLOOR-REQUEST-ID attribute that identifies The client MUST insert a FLOOR-REQUEST-ID attribute that identifies
the floor request at the floor control server. the floor request at the floor control server.
12.2.2. Receiving a Response 12.2.2. Receiving a Response
A message from the floor control server is considered a response to A message from the floor control server is considered a response to
the FloorRequestQuery message if the message from the floor control the FloorRequestQuery message if the message from the floor control
server has the same Conference ID, Transaction ID, and User ID as the server has the same Conference ID, Transaction ID, and User ID as the
FloorRequestQuery message, as described in Section 8.1. On receiving FloorRequestQuery message, as described in Section 8.1. On receiving
such a response, the client follows the rules in Section 9 that such a response, the client follows the rules in Section 9 that
relate to floor control server authentication. relate to floor control server authentication.
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the Error message. the Error message.
13. Floor Control Server Operations 13. Floor Control Server Operations
This section specifies how floor control servers can perform This section specifies how floor control servers can perform
different operations, such as granting a floor, using the protocol different operations, such as granting a floor, using the protocol
elements described in earlier sections. elements described in earlier sections.
On reception of a message from a client, the floor control server On reception of a message from a client, the floor control server
MUST check whether the value of the Primitive is supported. If it is MUST check whether the value of the Primitive is supported. If it is
not, the floor control server SHOULD send an Error message, as not, the floor control server MUST send an Error message, as
described in Section 13.8, with Error code 3 (Unknown Primitive). described in Section 13.8, with Error code 3 (Unknown Primitive).
On reception of a message from a client, the floor control server On reception of a message from a client, the floor control server
MUST check whether the value of the Conference ID matched an existing MUST check whether the value of the Conference ID matched an existing
conference. If it does not, the floor control server SHOULD send an conference. If it does not, the floor control server MUST send an
Error message, as described in Section 13.8, with Error code 1 Error message, as described in Section 13.8, with Error code 1
(Conference does not Exist). (Conference does not Exist).
On reception of a message from a client, the floor control server On reception of a message from a client, the floor control server
follows the rules in Section 9 that relate to the authentication of follows the rules in Section 9 that relate to the authentication of
the message. the message.
On reception of a message from a client, the floor control server On reception of a message from a client, the floor control server
MUST check whether it understands all the mandatory ('M' bit set) MUST check whether it understands all the mandatory ('M' bit set)
attributes in the message. If the floor control server does not attributes in the message. If the floor control server does not
understand all of them, the floor control server SHOULD send an Error understand all of them, the floor control server MUST send an Error
message, as described in Section 13.8, with Error code 4 (Unknown message, as described in Section 13.8, with Error code 4 (Unknown
Mandatory Attribute). The Error message SHOULD list the attributes Mandatory Attribute). The Error message SHOULD list the attributes
that were not understood. that were not understood.
13.1. Reception of a FloorRequest Message 13.1. Reception of a FloorRequest Message
On reception of a FloorRequest message, the floor control server On reception of a FloorRequest message, the floor control server
follows the rules in Section 9 that relate to client authentication follows the rules in Section 9 that relate to client authentication
and authorization. If while processing the FloorRequest message, the and authorization. If while processing the FloorRequest message, the
floor control server encounters an error, it SHOULD generate an Error floor control server encounters an error, it MUST generate an Error
response following the procedures described in Section 13.8. response following the procedures described in Section 13.8.
BFCP allows floor participants to have several ongoing floor BFCP allows floor participants to have several ongoing floor
requests for the same floor (e.g., the same floor participant can requests for the same floor (e.g., the same floor participant can
occupy more than one position in a queue at the same time). A occupy more than one position in a queue at the same time). A
floor control server that only supports a certain number of floor control server that only supports a certain number of
ongoing floor requests per floor participant (e.g., one) can use ongoing floor requests per floor participant (e.g., one) can use
Error Code 8 (You have Already Reached the Maximum Number of Error Code 8 (You have Already Reached the Maximum Number of
Ongoing Floor Requests for this Floor) to inform the floor Ongoing Floor Requests for this Floor) to inform the floor
participant. participant.
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When communicating over an unreliable transport and a When communicating over an unreliable transport and a
FloorRequestStatusAck message is not received within the transaction FloorRequestStatusAck message is not received within the transaction
failure window, the floor control server MUST retransmit the failure window, the floor control server MUST retransmit the
FloorRequestStatus message according to Section 6.2. FloorRequestStatus message according to Section 6.2.
13.2. Reception of a FloorRequestQuery Message 13.2. Reception of a FloorRequestQuery Message
On reception of a FloorRequestQuery message, the floor control server On reception of a FloorRequestQuery message, the floor control server
follows the rules in Section 9 that relate to client authentication follows the rules in Section 9 that relate to client authentication
and authorization. If while processing the FloorRequestQuery and authorization. If while processing the FloorRequestQuery
message, the floor control server encounters an error, it SHOULD message, the floor control server encounters an error, it MUST
generate an Error response following the procedures described in generate an Error response following the procedures described in
Section 13.8. Section 13.8.
The successful processing of a FloorRequestQuery message by a floor The successful processing of a FloorRequestQuery message by a floor
control server involves generating a FloorRequestStatus message, control server involves generating a FloorRequestStatus message,
which SHOULD be generated as soon as possible. which SHOULD be generated as soon as possible.
When communicating over an unreliable transport and upon receiving a When communicating over an unreliable transport and upon receiving a
FloorRequestQuery from a participant, the floor control server MUST FloorRequestQuery from a participant, the floor control server MUST
respond with a FloorRequestStatus message within the transaction respond with a FloorRequestStatus message within the transaction
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status of the floor request. The floor control server MAY provide status of the floor request. The floor control server MAY provide
information about the status of the floor request as it relates to information about the status of the floor request as it relates to
each of the floors being requested in the FLOOR-REQUEST-STATUS each of the floors being requested in the FLOOR-REQUEST-STATUS
attributes. attributes.
13.3. Reception of a UserQuery Message 13.3. Reception of a UserQuery Message
On reception of a UserQuery message, the floor control server follows On reception of a UserQuery message, the floor control server follows
the rules in Section 9 that relate to client authentication and the rules in Section 9 that relate to client authentication and
authorization. If while processing the UserQuery message, the floor authorization. If while processing the UserQuery message, the floor
control server encounters an error, it SHOULD generate an Error control server encounters an error, it MUST generate an Error
response following the procedures described in Section 13.8. response following the procedures described in Section 13.8.
The successful processing of a UserQuery message by a floor control The successful processing of a UserQuery message by a floor control
server involves generating a UserStatus message, which SHOULD be server involves generating a UserStatus message, which SHOULD be
generated as soon as possible. generated as soon as possible.
When communicating over an unreliable transport and upon receiving a When communicating over an unreliable transport and upon receiving a
UserQuery from a participant, the floor control server MUST respond UserQuery from a participant, the floor control server MUST respond
with a UserStatus message within the transaction failure window to with a UserStatus message within the transaction failure window to
complete the transaction. complete the transaction.
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The floor control server MAY provide information about the status of The floor control server MAY provide information about the status of
the floor request as it relates to each of the floors being requested the floor request as it relates to each of the floors being requested
in the FLOOR-REQUEST-STATUS attributes. in the FLOOR-REQUEST-STATUS attributes.
13.4. Reception of a FloorRelease Message 13.4. Reception of a FloorRelease Message
On reception of a FloorRelease message, the floor control server On reception of a FloorRelease message, the floor control server
follows the rules in Section 9 that relate to client authentication follows the rules in Section 9 that relate to client authentication
and authorization. If while processing the FloorRelease message, the and authorization. If while processing the FloorRelease message, the
floor control server encounters an error, it SHOULD generate an Error floor control server encounters an error, it MUST generate an Error
response following the procedures described in Section 13.8. response following the procedures described in Section 13.8.
The successful processing of a FloorRelease message by a floor The successful processing of a FloorRelease message by a floor
control server involves generating a FloorRequestStatus message, control server involves generating a FloorRequestStatus message,
which SHOULD be generated as soon as possible. which SHOULD be generated as soon as possible.
When communicating over an unreliable transport and upon receiving a When communicating over an unreliable transport and upon receiving a
FloorRelease from a participant, the floor control server MUST FloorRelease from a participant, the floor control server MUST
respond with a FloorRequestStatus message within the transaction respond with a FloorRequestStatus message within the transaction
failure window to complete the transaction. failure window to complete the transaction.
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Status value SHOULD be Released, if the floor (or floors) had been Status value SHOULD be Released, if the floor (or floors) had been
previously granted, or Cancelled, if the floor (or floors) had not previously granted, or Cancelled, if the floor (or floors) had not
been previously granted. The floor control server MAY add a STATUS- been previously granted. The floor control server MAY add a STATUS-
INFO attribute with extra information about the floor request. INFO attribute with extra information about the floor request.
13.5. Reception of a FloorQuery Message 13.5. Reception of a FloorQuery Message
On reception of a FloorQuery message, the floor control server On reception of a FloorQuery message, the floor control server
follows the rules in Section 9 that relate to client authentication. follows the rules in Section 9 that relate to client authentication.
If while processing the FloorQuery message, the floor control server If while processing the FloorQuery message, the floor control server
encounters an error, it SHOULD generate an Error response following encounters an error, it MUST generate an Error response following the
the procedures described in Section 13.8. procedures described in Section 13.8.
When communicating over an unreliable transport and upon receiving a When communicating over an unreliable transport and upon receiving a
FloorQuery from a participant, the floor control server MUST respond FloorQuery from a participant, the floor control server MUST respond
with a FloorStatus message within the transaction failure window to with a FloorStatus message within the transaction failure window to
complete the transaction. complete the transaction.
A floor control server receiving a FloorQuery message from a client A floor control server receiving a FloorQuery message from a client
SHOULD keep this client informed about the status of the floors SHOULD keep this client informed about the status of the floors
identified by FLOOR-ID attributes in the FloorQuery message. Floor identified by FLOOR-ID attributes in the FloorQuery message. Floor
Control Servers keep clients informed by using FloorStatus messages. Control Servers keep clients informed by using FloorStatus messages.
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When communicating over an unreliable transport and a FloorStatusAck When communicating over an unreliable transport and a FloorStatusAck
message is not received within the transaction failure window, the message is not received within the transaction failure window, the
floor control server MUST retransmit the FloorStatus message floor control server MUST retransmit the FloorStatus message
according to Section 6.2. according to Section 6.2.
13.6. Reception of a ChairAction Message 13.6. Reception of a ChairAction Message
On reception of a ChairAction message, the floor control server On reception of a ChairAction message, the floor control server
follows the rules in Section 9 that relate to client authentication follows the rules in Section 9 that relate to client authentication
and authorization. If while processing the ChairAction message, the and authorization. If while processing the ChairAction message, the
floor control server encounters an error, it SHOULD generate an Error floor control server encounters an error, it MUST generate an Error
response following the procedures described in Section 13.8. response following the procedures described in Section 13.8.
The successful processing of a ChairAction message by a floor control The successful processing of a ChairAction message by a floor control
server involves generating a ChairActionAck message, which SHOULD be server involves generating a ChairActionAck message, which SHOULD be
generated as soon as possible. generated as soon as possible.
When communicating over an unreliable transport and upon receiving a When communicating over an unreliable transport and upon receiving a
ChairAction from a chair, the floor control server MUST respond with ChairAction from a chair, the floor control server MUST respond with
a ChairActionAck message within the transaction failure window to a ChairActionAck message within the transaction failure window to
complete the transaction. complete the transaction.
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requesting that the floor control server assign a queue position requesting that the floor control server assign a queue position
(e.g., the last in the queue) to the floor request based on the local (e.g., the last in the queue) to the floor request based on the local
policy of the floor control server. (Of course, such a request only policy of the floor control server. (Of course, such a request only
applies if the floor control server implements a queue.) applies if the floor control server implements a queue.)
13.7. Reception of a Hello Message 13.7. Reception of a Hello Message
On reception of a Hello message, the floor control server follows the On reception of a Hello message, the floor control server follows the
rules in Section 9 that relate to client authentication. If while rules in Section 9 that relate to client authentication. If while
processing the Hello message, the floor control server encounters an processing the Hello message, the floor control server encounters an
error, it SHOULD generate an Error response following the procedures error, it MUST generate an Error response following the procedures
described in Section 13.8. described in Section 13.8.
If the version of BFCP specified in the Version field of the COMMON- If the version of BFCP specified in the Version field of the COMMON-
HEADER is supported by the floor control server, it MUST respond with HEADER is supported by the floor control server, it MUST respond with
the same version number in the HelloAck; this defines the version for the same version number in the HelloAck; this defines the version for
all subsequent BFCP messages within this BFCP Connection. If the all subsequent BFCP messages within this BFCP Connection. If the
version given in the Hello message is not supported, the receiving version given in the Hello message is not supported, the receiving
server MUST instead send an Error message with parameter value 12 server MUST instead send an Error message with parameter value 12
(Unsupported Version). (Unsupported Version).
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the BFCP Error Code subregistry in Section 15.4.] the BFCP Error Code subregistry in Section 15.4.]
The IANA has created a registry for BFCP parameters called "Binary The IANA has created a registry for BFCP parameters called "Binary
Floor Control Protocol (BFCP) Parameters". This registry has a Floor Control Protocol (BFCP) Parameters". This registry has a
number of subregistries, which are described in the following number of subregistries, which are described in the following
sections. sections.
15.1. Attribute Subregistry 15.1. Attribute Subregistry
This section establishes the Attribute subregistry under the BFCP This section establishes the Attribute subregistry under the BFCP
Parameters registry. As per the terminology in RFC 5226 [3], the Parameters registry. As per the terminology in RFC 5226 [5], the
registration policy for BFCP attributes shall be "Specification registration policy for BFCP attributes shall be "Specification
Required". For the purposes of this subregistry, the BFCP attributes Required". For the purposes of this subregistry, the BFCP attributes
for which IANA registration is requested MUST be defined by a for which IANA registration is requested MUST be defined by a
standards-track RFC. Such an RFC MUST specify the attribute's type, standards-track RFC. Such an RFC MUST specify the attribute's type,
name, format, and semantics. name, format, and semantics.
For each BFCP attribute, the IANA registers its type, its name, and For each BFCP attribute, the IANA registers its type, its name, and
the reference to the RFC where the attribute is defined. The the reference to the RFC where the attribute is defined. The
following table contains the initial values of this subregistry. following table contains the initial values of this subregistry.
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Table 7: Initial values of the BFCP Attribute subregistry Table 7: Initial values of the BFCP Attribute subregistry
15.2. Primitive Subregistry 15.2. Primitive Subregistry
[Editorial note: This section instructs the IANA to register the [Editorial note: This section instructs the IANA to register the
following new values for the BFCP Primitive subregistry: following new values for the BFCP Primitive subregistry:
FloorRequestStatusAck, FloorStatusAck, Goodbye, and GoodbyeAck.] FloorRequestStatusAck, FloorStatusAck, Goodbye, and GoodbyeAck.]
This section establishes the Primitive subregistry under the BFCP This section establishes the Primitive subregistry under the BFCP
Parameters registry. As per the terminology in RFC 5226 [3], the Parameters registry. As per the terminology in RFC 5226 [5], the
registration policy for BFCP primitives shall be "Specification registration policy for BFCP primitives shall be "Specification
Required". For the purposes of this subregistry, the BFCP primitives Required". For the purposes of this subregistry, the BFCP primitives
for which IANA registration is requested MUST be defined by a for which IANA registration is requested MUST be defined by a
standards-track RFC. Such an RFC MUST specify the primitive's value, standards-track RFC. Such an RFC MUST specify the primitive's value,
name, format, and semantics. name, format, and semantics.
For each BFCP primitive, the IANA registers its value, its name, and For each BFCP primitive, the IANA registers its value, its name, and
the reference to the RFC where the primitive is defined. The the reference to the RFC where the primitive is defined. The
following table contains the initial values of this subregistry. following table contains the initial values of this subregistry.
skipping to change at page 74, line 32 skipping to change at page 74, line 36
| 15 | FloorStatusAck | [RFC XXXX] | | 15 | FloorStatusAck | [RFC XXXX] |
| 16 | Goodbye | [RFC XXXX] | | 16 | Goodbye | [RFC XXXX] |
| 17 | GoodbyeAck | [RFC XXXX] | | 17 | GoodbyeAck | [RFC XXXX] |
+-------+-----------------------+------------+ +-------+-----------------------+------------+
Table 8: Initial values of the BFCP primitive subregistry Table 8: Initial values of the BFCP primitive subregistry
15.3. Request Status Subregistry 15.3. Request Status Subregistry
This section establishes the Request Status subregistry under the This section establishes the Request Status subregistry under the
BFCP Parameters registry. As per the terminology in RFC 5226 [3], BFCP Parameters registry. As per the terminology in RFC 5226 [5],
the registration policy for BFCP request status shall be the registration policy for BFCP request status shall be
"Specification Required". For the purposes of this subregistry, the "Specification Required". For the purposes of this subregistry, the
BFCP request status for which IANA registration is requested MUST be BFCP request status for which IANA registration is requested MUST be
defined by a standards-track RFC. Such an RFC MUST specify the value defined by a standards-track RFC. Such an RFC MUST specify the value
and the semantics of the request status. and the semantics of the request status.
For each BFCP request status, the IANA registers its value, its For each BFCP request status, the IANA registers its value, its
meaning, and the reference to the RFC where the request status is meaning, and the reference to the RFC where the request status is
defined. The following table contains the initial values of this defined. The following table contains the initial values of this
subregistry. subregistry.
skipping to change at page 75, line 26 skipping to change at page 75, line 26
Table 9: Initial values of the Request Status subregistry Table 9: Initial values of the Request Status subregistry
15.4. Error Code Subregistry 15.4. Error Code Subregistry
[Editorial note: This section instructs the IANA to register the [Editorial note: This section instructs the IANA to register the
following new values for the BFCP Error Code subregistry: 10, 11, following new values for the BFCP Error Code subregistry: 10, 11,
12, 13 and 14.] 12, 13 and 14.]
This section establishes the Error Code subregistry under the BFCP This section establishes the Error Code subregistry under the BFCP
Parameters registry. As per the terminology in RFC 5226 [3], the Parameters registry. As per the terminology in RFC 5226 [5], the
registration policy for BFCP error codes shall be "Specification registration policy for BFCP error codes shall be "Specification
Required". For the purposes of this subregistry, the BFCP error Required". For the purposes of this subregistry, the BFCP error
codes for which IANA registration is requested MUST be defined by a codes for which IANA registration is requested MUST be defined by a
standards-track RFC. Such an RFC MUST specify the value and the standards-track RFC. Such an RFC MUST specify the value and the
semantics of the error code, and any Error Specific Details that semantics of the error code, and any Error Specific Details that
apply to it. apply to it.
For each BFCP primitive, the IANA registers its value, its meaning, For each BFCP primitive, the IANA registers its value, its meaning,
and the reference to the RFC where the primitive is defined. The and the reference to the RFC where the primitive is defined. The
following table contains the initial values of this subregistry. following table contains the initial values of this subregistry.
skipping to change at page 76, line 31 skipping to change at page 76, line 31
| 12 | Unsupported Version | [RFC XXXX] | | 12 | Unsupported Version | [RFC XXXX] |
| 13 | Incorrect Message Length | [RFC XXXX] | | 13 | Incorrect Message Length | [RFC XXXX] |
| 14 | Generic Error | [RFC XXXX] | | 14 | Generic Error | [RFC XXXX] |
+-------+--------------------------------------+------------+ +-------+--------------------------------------+------------+
Table 10: Initial Values of the Error Code subregistry Table 10: Initial Values of the Error Code subregistry
16. Changes from RFC 4582 16. Changes from RFC 4582
Following is the list of technical changes and other non-trivial Following is the list of technical changes and other non-trivial
fixes from [15]. fixes from [2].
16.1. Extensions for an unreliable transport 16.1. Extensions for an unreliable transport
Main purpose of this work was to revise the specification to support Main purpose of this work was to revise the specification to support
BFCP over an unreliable transport, resulting in the following BFCP over an unreliable transport, resulting in the following
changes: changes:
Overview of Operation (Section 4): 1. Overview of Operation (Section 4):
Changed the description of client-initiated and server- Changed the description of client-initiated and server-initiated
initiated transactions, referring to Section 8. transactions, referring to Section 8.
COMMON-HEADER Format (Section 5.1): 2. COMMON-HEADER Format (Section 5.1):
Ver(sion) field, where the value 2 is used for the extensions Ver(sion) field, where the value 2 is used for the extensions
for an unreliable transport. Added new R and F flag-bits for for an unreliable transport. Added new R and F flag-bits for an
an unreliable transport. Res(erved) field is now 3 bit. New unreliable transport. Res(erved) field is now 3 bit. New
optional Fragment Offset and Fragment Length fields. optional Fragment Offset and Fragment Length fields.
New primitives (Section 5.1): 3. New primitives (Section 5.1):
Added four new primitives: FloorRequestStatusAck, Added four new primitives: FloorRequestStatusAck,
FloorStatusAck, Goodbye, and GoodbyeAck. FloorStatusAck, Goodbye, and GoodbyeAck.
New error codes (Section 5.2.6): 4. New error codes (Section 5.2.6):
Added three new error codes: "Unable to Parse Message", "Use Added three new error codes: "Unable to Parse Message", "Use
DTLS" and "Unsupported Version". Note that two additional DTLS" and "Unsupported Version". Note that two additional error
error codes were added, see Section 16.2. codes were added, see Section 16.2.
ABNF for new primitives (Section 5.3): 5. ABNF for new primitives (Section 5.3):
New subsections with normative ABNF for the new primitives. New subsections with normative ABNF for the new primitives.
Transport split in two (Section 6): 6. Transport split in two (Section 6):
Section 6 specifying the transport was split in two Section 6 specifying the transport was split in two subsections;
subsections; Section 6.1 for a reliable transport and Section 6.1 for a reliable transport and Section 6.2 for an
Section 6.2 for an unreliable transport. Where the unreliable transport. Where the specification for an unreliable
specification for an unreliable transport amongst other issues transport amongst other issues deals with reliability,
deals with reliability, congestion control, fragmentation and congestion control, fragmentation and ICMP.
ICMP.
Mandate DTLS (Section 7 and Section 9): 7. Mandate DTLS (Section 7 and Section 9):
Mandate DTLS support when transport over UDP is used. Mandate DTLS support when transport over UDP is used.
Transaction changes (Section 8): 8. Transaction changes (Section 8):
Server-initiated transactions over an unreliable transport has Server-initiated transactions over an unreliable transport has
non-zero and unique Transaction ID. Over an unreliable non-zero and unique Transaction ID. Over an unreliable
transport, the retransmit timers T1 and T2 described in transport, the retransmit timers T1 and T2 described in
Section 8.3 applies. Section 8.3 apply.
Requiring timely response (Section 10.1.2, Section 10.2.2, 9. Requiring timely response (Section 8.3, Section 10.1.2,
Section 11.2, Section 12.1.2, Section 12.2.2, Section 12.3.2, Section 10.2.2, Section 11.2, Section 12.1.2, Section 12.2.2,
Section 12.4.2, Section 10.1.3 and Section 12.1.3): Section 12.3.2, Section 12.4.2, Section 10.1.3 and
Describing that a given response must be sent within the Section 12.1.3):
transaction failure window to complete the transaction. Describing that a given response must be sent within the
transaction failure window to complete the transaction.
Updated IANA Considerations (Section 15): 10. Updated IANA Considerations (Section 15):
Added the new primitives and error codes to Section 15.2 and Added the new primitives and error codes to Section 15.2 and
Section 15.4 respectively. Section 15.4 respectively.
Examples over an unreliable transport (Appendix A): 11. Examples over an unreliable transport (Appendix A):
Added sample interactions over an unreliable transport for the Added sample interactions over an unreliable transport for the
scenarios in Figure 2 and Figure 3 scenarios in Figure 2 and Figure 3
Motivation for an unreliable transport (Appendix B): 12. Motivation for an unreliable transport (Appendix B):
Introduction to and motivation for extending BFCP to support an Introduction to and motivation for extending BFCP to support an
unreliable transport. unreliable transport.
16.2. Other changes 16.2. Other changes
The clarification and bug fixes: The clarification and bug fixes:
ABNF fixes (Figure 22, Figure 24, ="fig:reqby-information"/>, 1. ABNF fixes (Figure 22, Figure 24, ="fig:reqby-information"/>,
Figure 28, Figure 30, and the ABNF figures in Section 5.3): Figure 28, Figure 30, and the ABNF figures in Section 5.3):
Although formally correct in [15], the notation has changed in a Although formally correct in [2], the notation has changed in a
number of Figures to an equivalent form for clarity, e.g., number of Figures to an equivalent form for clarity, e.g.,
s/*1(FLOOR-ID)/[FLOOR-ID]/ in Figure 38 and s/*[XXX]/*(XXX)/ in s/*1(FLOOR-ID)/[FLOOR-ID]/ in Figure 38 and s/*[XXX]/*(XXX)/ in
the other figures. the other figures.
Typo (Section 12.4.2): 2. Typo (Section 12.4.2):
Change from SUPPORTED-PRIMITVIES to SUPPORTED-PRIMITIVES in the Change from SUPPORTED-PRIMITVIES to SUPPORTED-PRIMITIVES in the
second paragraph. second paragraph.
Corrected attribute type (Section 13.1.1): 3. Corrected attribute type (Section 13.1.1):
Change from PARTICIPANT-PROVIDED-INFO to PRIORITY attributed in Change from PARTICIPANT-PROVIDED-INFO to PRIORITY attributed in
the eighth paragraph, since the note below describes priority and the eighth paragraph, since the note below describes priority and
that the last paragraph deals with PARTICIPANT-PROVIDED-INFO. that the last paragraph deals with PARTICIPANT-PROVIDED-INFO.
New error codes (Section 5.2.6): 4. New error codes (Section 5.2.6):
Added two additional error codes: "Incorrect Message Length" and Added two additional error codes: "Incorrect Message Length" and
"Generic Error". "Generic Error".
5. Assorted clarifications (Across the document):
Non-functional language clarifications and some corrections in
the normative language as a result of reviews.
17. Acknowledgements 17. Acknowledgements
The XCON WG chairs, Adam Roach and Alan Johnston, provided useful The XCON WG chairs, Adam Roach and Alan Johnston, provided useful
ideas for RFC 4582 [15]. Additionally, Xiaotao Wu, Paul Kyzivat, ideas for RFC 4582 [2]. Additionally, Xiaotao Wu, Paul Kyzivat,
Jonathan Rosenberg, Miguel A. Garcia-Martin, Mary Barnes, Ben Jonathan Rosenberg, Miguel A. Garcia-Martin, Mary Barnes, Ben
Campbell, Dave Morgan, and Oscar Novo provided useful comments during Campbell, Dave Morgan, and Oscar Novo provided useful comments during
the work with RFC 4582. The authors also acknowledge contributions the work with RFC 4582. The authors also acknowledge contributions
to the revision of BFCP for use over an unreliable transport from to the revision of BFCP for use over an unreliable transport from
Geir Arne Sandbakken who had the initial idea, Alfred E. Heggestad, Geir Arne Sandbakken who had the initial idea, Alfred E. Heggestad,
Trond G. Andersen, Gonzalo Camarillo, Roni Even, Lorenzo Miniero, Trond G. Andersen, Gonzalo Camarillo, Roni Even, Lorenzo Miniero,
Joerg Ott, Eoin McLeod, Mark K. Thompson, Hadriel Kaplan, Dan Wing, Joerg Ott, Eoin McLeod, Mark K. Thompson, Hadriel Kaplan, Dan Wing,
Cullen Jennings, David Benham, Nivedita Melinkeri, Woo Johnman, Cullen Jennings, David Benham, Nivedita Melinkeri, Woo Johnman,
Vijaya Mandava and Alan Ford. In the final phase Ernst Horvath did a Vijaya Mandava and Alan Ford. In the final phase Ernst Horvath did a
thorough review revealing issues that needed clarification and thorough review revealing issues that needed clarification and
changes. changes. Useful and important final reviews were done by Mary
Barnes.
18. References 18. References
18.1. Normative References 18.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997. Levels", BCP 14, RFC 2119, March 1997.
[2] Crocker, D. and P. Overell, "Augmented BNF for Syntax [2] Camarillo, G., Ott, J., and K. Drage, "The Binary Floor Control
Protocol (BFCP)", RFC 4582, November 2006.
[3] Camarillo, G., "Connection Establishment in the Binary Floor
Control Protocol (BFCP)", RFC 5018, September 2007.
[4] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008. Specifications: ABNF", STD 68, RFC 5234, January 2008.
[3] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA [5] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
Considerations Section in RFCs", BCP 26, RFC 5226, May 2008. Considerations Section in RFCs", BCP 26, RFC 5226, May 2008.
[4] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) [6] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS)
Protocol Version 1.2", RFC 5246, August 2008. Protocol Version 1.2", RFC 5246, August 2008.
[5] Rescorla, E. and N. Modadugu, "Datagram Transport Layer [7] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security Version 1.2", RFC 6347, January 2012. Security Version 1.2", RFC 6347, January 2012.
[6] Yergeau, F., "UTF-8, a transformation format of ISO 10646", [8] Yergeau, F., "UTF-8, a transformation format of ISO 10646",
STD 63, RFC 3629, November 2003. STD 63, RFC 3629, November 2003.
[7] Camarillo, G. and T. Kristensen, "Session Description Protocol [9] Camarillo, G. and T. Kristensen, "Session Description Protocol
(SDP) Format for Binary Floor Control Protocol (BFCP) Streams", (SDP) Format for Binary Floor Control Protocol (BFCP) Streams",
draft-ietf-bfcpbis-rfc4583bis-08 (work in progress), draft-ietf-bfcpbis-rfc4583bis-09 (work in progress),
November 2013. February 2014.
[8] Wing, D., "Symmetric RTP / RTP Control Protocol (RTCP)", [10] Wing, D., "Symmetric RTP / RTP Control Protocol (RTCP)",
BCP 131, RFC 4961, July 2007. BCP 131, RFC 4961, July 2007.
[9] Rosenberg, J., Mahy, R., Matthews, P., and D. Wing, "Session [11] Rosenberg, J., Mahy, R., Matthews, P., and D. Wing, "Session
Traversal Utilities for NAT (STUN)", RFC 5389, October 2008. Traversal Utilities for NAT (STUN)", RFC 5389, October 2008.
18.2. Informational References 18.2. Informational References
[10] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model with [12] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model with
Session Description Protocol (SDP)", RFC 3264, June 2002. Session Description Protocol (SDP)", RFC 3264, June 2002.
[11] Koskelainen, P., Ott, J., Schulzrinne, H., and X. Wu, [13] Koskelainen, P., Ott, J., Schulzrinne, H., and X. Wu,
"Requirements for Floor Control Protocols", RFC 4376, "Requirements for Floor Control Protocols", RFC 4376,
February 2006. February 2006.
[12] Barnes, M., Boulton, C., and O. Levin, "A Framework for [14] Barnes, M., Boulton, C., and O. Levin, "A Framework for
Centralized Conferencing", RFC 5239, June 2008. Centralized Conferencing", RFC 5239, June 2008.
[13] Rosenberg, J., "Interactive Connectivity Establishment (ICE): A [15] Rosenberg, J., "Interactive Connectivity Establishment (ICE): A
Protocol for Network Address Translator (NAT) Traversal for Protocol for Network Address Translator (NAT) Traversal for
Offer/Answer Protocols", RFC 5245, April 2010. Offer/Answer Protocols", RFC 5245, April 2010.
[14] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., [16] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,
Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP:
Session Initiation Protocol", RFC 3261, June 2002. Session Initiation Protocol", RFC 3261, June 2002.
[15] Camarillo, G., Ott, J., and K. Drage, "The Binary Floor Control [17] Novo, O., Camarillo, G., Morgan, D., and J. Urpalainen,
Protocol (BFCP)", RFC 4582, November 2006. "Conference Information Data Model for Centralized Conferencing
(XCON)", RFC 6501, March 2012.
[16] Camarillo, G., "Connection Establishment in the Binary Floor
Control Protocol (BFCP)", RFC 5018, September 2007.
[17] Barnes, M., Boulton, C., Romano, S., and H. Schulzrinne, [18] Barnes, M., Boulton, C., Romano, S., and H. Schulzrinne,
"Centralized Conferencing Manipulation Protocol", RFC 6503, "Centralized Conferencing Manipulation Protocol", RFC 6503,
March 2012. March 2012.
[18] Barnes, M., Miniero, L., Presta, R., and SP. Romano, [19] Barnes, M., Miniero, L., Presta, R., and SP. Romano,
"Centralized Conferencing Manipulation Protocol (CCMP) Call "Centralized Conferencing Manipulation Protocol (CCMP) Call
Flow Examples", RFC 6504, March 2012. Flow Examples", RFC 6504, March 2012.
[19] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191, [20] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191,
November 1990. November 1990.
[20] McCann, J., Deering, S., and J. Mogul, "Path MTU Discovery for [21] McCann, J., Deering, S., and J. Mogul, "Path MTU Discovery for
IP version 6", RFC 1981, August 1996. IP version 6", RFC 1981, August 1996.
[21] Mathis, M. and J. Heffner, "Packetization Layer Path MTU [22] Mathis, M. and J. Heffner, "Packetization Layer Path MTU
Discovery", RFC 4821, March 2007. Discovery", RFC 4821, March 2007.
[22] Fischl, J., Tschofenig, H., and E. Rescorla, "Framework for [23] Fischl, J., Tschofenig, H., and E. Rescorla, "Framework for
Establishing a Secure Real-time Transport Protocol (SRTP) Establishing a Secure Real-time Transport Protocol (SRTP)
Security Context Using Datagram Transport Layer Security Security Context Using Datagram Transport Layer Security
(DTLS)", RFC 5763, May 2010. (DTLS)", RFC 5763, May 2010.
[23] Huitema, C., "Teredo: Tunneling IPv6 over UDP through Network [24] Huitema, C., "Teredo: Tunneling IPv6 over UDP through Network
Address Translations (NATs)", RFC 4380, February 2006. Address Translations (NATs)", RFC 4380, February 2006.
[24] Eggert, L. and G. Fairhurst, "Unicast UDP Usage Guidelines for [25] Eggert, L. and G. Fairhurst, "Unicast UDP Usage Guidelines for
Application Designers", BCP 145, RFC 5405, November 2008. Application Designers", BCP 145, RFC 5405, November 2008.
[25] Thaler, D., "Teredo Extensions", RFC 6081, January 2011. [26] Thaler, D., "Teredo Extensions", RFC 6081, January 2011.
[26] Stewart, R., "Stream Control Transmission Protocol", RFC 4960, [27] Stewart, R., "Stream Control Transmission Protocol", RFC 4960,
September 2007. September 2007.
[27] Rosenberg, J., Keranen, A., Lowekamp, B., and A. Roach, "TCP [28] Rosenberg, J., Keranen, A., Lowekamp, B., and A. Roach, "TCP
Candidates with Interactive Connectivity Establishment (ICE)", Candidates with Interactive Connectivity Establishment (ICE)",
RFC 6544, March 2012. RFC 6544, March 2012.
[28] Manner, J., Varis, N., and B. Briscoe, "Generic UDP Tunnelling [29] Manner, J., Varis, N., and B. Briscoe, "Generic UDP Tunnelling
(GUT)", draft-manner-tsvwg-gut-02 (work in progress), (GUT)", draft-manner-tsvwg-gut-02 (work in progress),
July 2010. July 2010.
[29] Stucker, B., Tschofenig, H., and G. Salgueiro, "Analysis of [30] Stucker, B., Tschofenig, H., and G. Salgueiro, "Analysis of
Middlebox Interactions for Signaling Protocol Communication Middlebox Interactions for Signaling Protocol Communication
along the Media Path", along the Media Path",
draft-ietf-mmusic-media-path-middleboxes-05 (work in progress), draft-ietf-mmusic-media-path-middleboxes-05 (work in progress),
July 2012. July 2012.
[30] Guha, S. and P. Francis, "Characterization and Measurement of [31] Guha, S. and P. Francis, "Characterization and Measurement of
TCP Traversal through NATs and Firewalls", 2005, TCP Traversal through NATs and Firewalls", 2005,
<http://saikat.guha.cc/pub/imc05-tcpnat.pdf/>. <http://saikat.guha.cc/pub/imc05-tcpnat.pdf/>.
[31] Ford, B., Srisuresh, P., and D. Kegel, "Peer-to-Peer [32] Ford, B., Srisuresh, P., and D. Kegel, "Peer-to-Peer
Communication Across Network Address Translators", April 2005, Communication Across Network Address Translators", April 2005,
<http://www.brynosaurus.com/pub/net/p2pnat.pdf/>. <http://www.brynosaurus.com/pub/net/p2pnat.pdf/>.
Appendix A. Example Call Flows for BFCP over an Unreliable Transport Appendix A. Example Call Flows for BFCP over an Unreliable Transport
With reference to Section 4.1, the following figures show With reference to Section 4.1, the following figures show
representative call-flows for requesting and releasing a floor, and representative call-flows for requesting and releasing a floor, and
obtaining status information about a floor when BFCP is deployed over obtaining status information about a floor when BFCP is deployed over
an unreliable transport. The figures here show a loss-less an unreliable transport. The figures here show a loss-less
interaction. interaction.
skipping to change at page 81, line 42 skipping to change at page 82, line 4
|User ID: 234 | |User ID: 234 |
|FLOOR-REQUEST-INFORMATION | |FLOOR-REQUEST-INFORMATION |
| Floor Request ID: 789 | | Floor Request ID: 789 |
| OVERALL-REQUEST-STATUS | | OVERALL-REQUEST-STATUS |
| Request Status: Pending | | Request Status: Pending |
| FLOOR-REQUEST-STATUS | | FLOOR-REQUEST-STATUS |
| Floor ID: 543 | | Floor ID: 543 |
|<----------------------------------------------| |<----------------------------------------------|
| | | |
|(3) FloorRequestStatus | |(3) FloorRequestStatus |
|Transaction ID: 4098 | |Transaction ID: 124 |
|User ID: 234 | |User ID: 234 |
|FLOOR-REQUEST-INFORMATION | |FLOOR-REQUEST-INFORMATION |
| Floor Request ID: 789 | | Floor Request ID: 789 |
| OVERALL-REQUEST-STATUS | | OVERALL-REQUEST-STATUS |
| Request Status: Accepted | | Request Status: Accepted |
| Queue Position: 1st | | Queue Position: 1st |
| FLOOR-REQUEST-STATUS | | FLOOR-REQUEST-STATUS |
| Floor ID: 543 | | Floor ID: 543 |
|<----------------------------------------------| |<----------------------------------------------|
| | | |
|(4) FloorRequestStatusAck | |(4) FloorRequestStatusAck |
|Transaction ID: 4098 | |Transaction ID: 124 |
|User ID: 234 | |User ID: 234 |
|---------------------------------------------->| |---------------------------------------------->|
| | | |
|(5) FloorRequestStatus | |(5) FloorRequestStatus |
|Transaction ID: 4130 | |Transaction ID: 125 |
|User ID: 234 | |User ID: 234 |
|FLOOR-REQUEST-INFORMATION | |FLOOR-REQUEST-INFORMATION |
| Floor Request ID: 789 | | Floor Request ID: 789 |
| OVERALL-REQUEST-STATUS | | OVERALL-REQUEST-STATUS |
| Request Status: Granted | | Request Status: Granted |
| FLOOR-REQUEST-STATUS | | FLOOR-REQUEST-STATUS |
| Floor ID: 543 | | Floor ID: 543 |
|<----------------------------------------------| |<----------------------------------------------|
| | | |
|(6) FloorRequestStatusAck | |(6) FloorRequestStatusAck |
|Transaction ID: 4130 | |Transaction ID: 125 |
|User ID: 234 | |User ID: 234 |
|---------------------------------------------->| |---------------------------------------------->|
| | | |
|(7) FloorRelease | |(7) FloorRelease |
|Transaction ID: 154 | |Transaction ID: 126 |
|User ID: 234 | |User ID: 234 |
|FLOOR-REQUEST-ID: 789 | |FLOOR-REQUEST-ID: 789 |
|---------------------------------------------->| |---------------------------------------------->|
| | | |
|(8) FloorRequestStatus | |(8) FloorRequestStatus |
|Transaction ID: 154 | |Transaction ID: 126 |
|User ID: 234 | |User ID: 234 |
|FLOOR-REQUEST-INFORMATION | |FLOOR-REQUEST-INFORMATION |
| Floor Request ID: 789 | | Floor Request ID: 789 |
| OVERALL-REQUEST-STATUS | | OVERALL-REQUEST-STATUS |
| Request Status: Released | | Request Status: Released |
| FLOOR-REQUEST-STATUS | | FLOOR-REQUEST-STATUS |
| Floor ID: 543 | | Floor ID: 543 |
|<----------------------------------------------| |<----------------------------------------------|
Figure 48: Requesting and releasing a floor Figure 48: Requesting and releasing a floor
skipping to change at page 83, line 39 skipping to change at page 83, line 47
| OVERALL-REQUEST-STATUS | | OVERALL-REQUEST-STATUS |
| Request Status: Accepted | | Request Status: Accepted |
| Queue Position: 2nd | | Queue Position: 2nd |
| FLOOR-REQUEST-STATUS | | FLOOR-REQUEST-STATUS |
| Floor ID: 543 | | Floor ID: 543 |
| BENEFICIARY-INFORMATION | | BENEFICIARY-INFORMATION |
| Beneficiary ID: 154 | | Beneficiary ID: 154 |
|<----------------------------------------------| |<----------------------------------------------|
| | | |
|(3) FloorStatus | |(3) FloorStatus |
|Transaction ID: 4319 | |Transaction ID: 258 |
|User ID: 234 | |User ID: 234 |
|FLOOR-ID:543 | |FLOOR-ID:543 |
|FLOOR-REQUEST-INFORMATION | |FLOOR-REQUEST-INFORMATION |
| Floor Request ID: 764 | | Floor Request ID: 764 |
| OVERALL-REQUEST-STATUS | | OVERALL-REQUEST-STATUS |
| Request Status: Granted | | Request Status: Granted |
| FLOOR-REQUEST-STATUS | | FLOOR-REQUEST-STATUS |
| Floor ID: 543 | | Floor ID: 543 |
| BENEFICIARY-INFORMATION | | BENEFICIARY-INFORMATION |
| Beneficiary ID: 124 | | Beneficiary ID: 124 |
skipping to change at page 84, line 15 skipping to change at page 84, line 22
| OVERALL-REQUEST-STATUS | | OVERALL-REQUEST-STATUS |
| Request Status: Accepted | | Request Status: Accepted |
| Queue Position: 1st | | Queue Position: 1st |
| FLOOR-REQUEST-STATUS | | FLOOR-REQUEST-STATUS |
| Floor ID: 543 | | Floor ID: 543 |
| BENEFICIARY-INFORMATION | | BENEFICIARY-INFORMATION |
| Beneficiary ID: 154 | | Beneficiary ID: 154 |
|<----------------------------------------------| |<----------------------------------------------|
| | | |
|(4) FloorStatusAck | |(4) FloorStatusAck |
|Transaction ID: 4319 | |Transaction ID: 258 |
|User ID: 234 | |User ID: 234 |
|---------------------------------------------->| |---------------------------------------------->|
| | | |
|(5) FloorStatus | |(5) FloorStatus |
|Transaction ID: 4392 | |Transaction ID: 259 |
|User ID: 234 | |User ID: 234 |
|FLOOR-ID:543 | |FLOOR-ID:543 |
|FLOOR-REQUEST-INFORMATION | |FLOOR-REQUEST-INFORMATION |
| Floor Request ID: 635 | | Floor Request ID: 635 |
| OVERALL-REQUEST-STATUS | | OVERALL-REQUEST-STATUS |
| Request Status: Granted | | Request Status: Granted |
| FLOOR-REQUEST-STATUS | | FLOOR-REQUEST-STATUS |
| Floor ID: 543 | | Floor ID: 543 |
| BENEFICIARY-INFORMATION | | BENEFICIARY-INFORMATION |
| Beneficiary ID: 154 | | Beneficiary ID: 154 |
|<----------------------------------------------| |<----------------------------------------------|
| | | |
|(6) FloorStatusAck | |(6) FloorStatusAck |
|Transaction ID: 4392 | |Transaction ID: 259 |
|User ID: 234 | |User ID: 234 |
|---------------------------------------------->| |---------------------------------------------->|
Figure 49: Obtaining status information about a floor Figure 49: Obtaining status information about a floor
Appendix B. Motivation for Supporting an Unreliable Transport Appendix B. Motivation for Supporting an Unreliable Transport
[Editorial note: This appendix is contained in this draft as an This appendix is contained in this document as an aid to understand
aid and rationale for new readers and reviewers. However, it is the background and rationale for adding support for unreliable
not yet decided whether this Appendix will be part of the final transport.
(RFC) version or not.]
B.1. Motivation B.1. Motivation
In existing video conferencing deployments, BFCP is used to manage In existing video conferencing deployments, BFCP is used to manage
the floor for the content sharing associated with the conference. the floor for the content sharing associated with the conference.
For peer to peer scenarios, including business to business For peer to peer scenarios, including business to business
conferences and point to point conferences in general, it is conferences and point to point conferences in general, it is
frequently the case that one or both endpoints exists behind a NAT. frequently the case that one or both endpoints exists behind a NAT.
BFCP roles are negotiated in the offer/answer exchange as specified BFCP roles are negotiated in the offer/answer exchange as specified
in [7], resulting in one endpoint being responsible for opening the in [9], resulting in one endpoint being responsible for opening the
TCP connection used for the BFCP communication. TCP connection used for the BFCP communication.
+---------+ +---------+
| Network | | Network |
+---------+ +---------+
+-----+ / \ +-----+ +-----+ / \ +-----+
| NAT |/ \| NAT | | NAT |/ \| NAT |
+-----+ +-----+ +-----+ +-----+
+----+ / \ +----+ +----+ / \ +----+
|BFCP|/ \|BFCP| |BFCP|/ \|BFCP|
skipping to change at page 85, line 35 skipping to change at page 85, line 36
+----+ +----+ +----+ +----+
Figure 50: Use Case Figure 50: Use Case
The communication session between the video conferencing endpoints The communication session between the video conferencing endpoints
typically consists of a number of RTP over UDP media streams, for typically consists of a number of RTP over UDP media streams, for
audio and video, and a BFCP connection for floor control. Existing audio and video, and a BFCP connection for floor control. Existing
deployments are most common in, but not limited to, enterprise deployments are most common in, but not limited to, enterprise
networks. In existing deployments, NAT traversal for the RTP streams networks. In existing deployments, NAT traversal for the RTP streams
works using ICE and/or other methods, including those described in works using ICE and/or other methods, including those described in
[29]. [30].
When enhancing an existing SIP based video conferencing deployment When enhancing an existing SIP based video conferencing deployment
with support for content sharing, the BFCP connection often poses a with support for content sharing, the BFCP connection often poses a
problem. The reasons for this fall into two general classes. First, problem. The reasons for this fall into two general classes. First,
there may be a strong preference for UDP based signaling in general. there may be a strong preference for UDP based signaling in general.
On high capacity endpoints (e.g., PSTN gateways or SIP/H.323 inter- On high capacity endpoints (e.g., PSTN gateways or SIP/H.323 inter-
working gateways), TCP can suffer from head of line blocking, and it working gateways), TCP can suffer from head of line blocking, and it
uses many kernel buffers. Network operators view UDP as a way to uses many kernel buffers. Network operators view UDP as a way to
avoid both of these. Second, establishment and traversal of the TCP avoid both of these. Second, establishment and traversal of the TCP
connection involving ephemeral ports, as is typically the case with connection involving ephemeral ports, as is typically the case with
BFCP over TCP, can be problematic, as described in Appendix A of BFCP over TCP, can be problematic, as described in Appendix A of
[27]. A broad study of NAT behavior and peer-to-peer TCP [28]. A broad study of NAT behavior and peer-to-peer TCP
establishment for a comprehensive set of TCP NAT traversal techniques establishment for a comprehensive set of TCP NAT traversal techniques
over a wide range of commercial NAT products concluded it was not over a wide range of commercial NAT products concluded it was not
possible to establish a TCP connection in 11% of the cases [30]. The possible to establish a TCP connection in 11% of the cases [31]. The
results are worse when focusing on enterprise NATs. A study of hole results are worse when focusing on enterprise NATs. A study of hole
punching as a NAT traversal technique across a wide variety of punching as a NAT traversal technique across a wide variety of
deployed NATs reported consistently higher success rates when using deployed NATs reported consistently higher success rates when using
UDP than when using TCP [31]. UDP than when using TCP [32].
It is worth noticing that BFCP over UDP were already used in real It is worth noticing that BFCP over UDP were already used in real
deployments, underlining the necessity to specify a common way to deployments, underlining the necessity to specify a common way to
exchange BFCP messages where TCP is not appropriate, to avoid a exchange BFCP messages where TCP is not appropriate, to avoid a
situation where multiple different and non-interoperable would co- situation where multiple different and non-interoperable would co-
exist in the market. The purpose of this draft is to formalize and exist in the market. The purpose of this draft is to formalize and
publish the extension from the standard specification to facilitate publish the extension from the standard specification to facilitate
complete interoperability between implementations. complete interoperability between implementations.
B.1.1. Alternatives Considered B.1.1. Alternatives Considered
skipping to change at page 86, line 33 skipping to change at page 86, line 35
to address the use case targeted by this draft. The last to address the use case targeted by this draft. The last
alternative, presented in Appendix B.1.1.7, is the selected one and alternative, presented in Appendix B.1.1.7, is the selected one and
is specified in this draft. is specified in this draft.
It is also worth noting that the IETF Transport Area were asked for a It is also worth noting that the IETF Transport Area were asked for a
way to tunnel TCP over UDP, but at that point there was no consensus way to tunnel TCP over UDP, but at that point there was no consensus
on how to achieve that. on how to achieve that.
B.1.1.1. ICE TCP B.1.1.1. ICE TCP
ICE TCP [27] extends ICE to TCP based media, including the ability to ICE TCP [28] extends ICE to TCP based media, including the ability to
offer a mix of TCP and UDP based candidates for a single stream. ICE offer a mix of TCP and UDP based candidates for a single stream. ICE
TCP has, in general, a lower success probability for enabling TCP TCP has, in general, a lower success probability for enabling TCP
connectivity without a relay if both of the hosts are behind a NAT connectivity without a relay if both of the hosts are behind a NAT
(see Appendix A of [27]) than enabling UDP connectivity in the same (see Appendix A of [28]) than enabling UDP connectivity in the same
scenarios. The happens because many of the currently deployed NATs scenarios. The happens because many of the currently deployed NATs
in video conferencing networks do not support the flow of TCP hand in video conferencing networks do not support the flow of TCP hand
shake packets seen in case of TCP simultaneous-open, either because shake packets seen in case of TCP simultaneous-open, either because
they do not allow incoming TCP SYN packets from an address to which a they do not allow incoming TCP SYN packets from an address to which a
SYN packet has been sent to recently, or because they do not properly SYN packet has been sent to recently, or because they do not properly
process the subsequent SYNACK. Implementing various techniques process the subsequent SYNACK. Implementing various techniques
advocated for candidate collection in [27] should increase the advocated for candidate collection in [28] should increase the
success probability, but many of these techniques require support success probability, but many of these techniques require support
from some network elements (e.g., from the NATs). Such support is from some network elements (e.g., from the NATs). Such support is
not common in enterprise NATs. not common in enterprise NATs.
B.1.1.2. Teredo B.1.1.2. Teredo
Teredo [23] enables nodes located behind one or more IPv4 NATs to Teredo [24] enables nodes located behind one or more IPv4 NATs to
obtain IPv6 connectivity by tunneling packets over UDP. Teredo obtain IPv6 connectivity by tunneling packets over UDP. Teredo
extensions [25] provide additional capabilities to Teredo, including extensions [26] provide additional capabilities to Teredo, including
support for more types of NATs and support for more efficient support for more types of NATs and support for more efficient
communication. communication.
As defined, Teredo could be used to make BFCP work for the video As defined, Teredo could be used to make BFCP work for the video
conferencing use cases addressed in this draft. However, running the conferencing use cases addressed in this draft. However, running the
service requires the help of "Teredo servers" and "Teredo relays" service requires the help of "Teredo servers" and "Teredo relays"
[23]. These servers and relays generally do not exist in the [24]. These servers and relays generally do not exist in the
existing video conferencing deployments. It also requires IPv6 existing video conferencing deployments. It also requires IPv6
awareness on the endpoints. It should also be noted that ICMP6, as awareness on the endpoints. It should also be noted that ICMP6, as
used with Teredo to complete an initial protocol exchange and confirm used with Teredo to complete an initial protocol exchange and confirm
that the appropriate NAT bindings have been set up, is not a that the appropriate NAT bindings have been set up, is not a
conventional feature of IPv4 or even IPv6, and some currently conventional feature of IPv4 or even IPv6, and some currently
deployed IPv6 firewalls discard ICMP messages. As these networks deployed IPv6 firewalls discard ICMP messages. As these networks
continue to evolve and tackle the transaction to IPv6, Teredo servers continue to evolve and tackle the transaction to IPv6, Teredo servers
and relays may be deployed, making Teredo available as a suitable and relays may be deployed, making Teredo available as a suitable
alternative to BFCP over UDP. alternative to BFCP over UDP.
B.1.1.3. GUT B.1.1.3. GUT
GUT [28] attempts to facilitate tunneling over UDP by encapsulating GUT [29] attempts to facilitate tunneling over UDP by encapsulating
the native transport protocol and its payload (in general the whole the native transport protocol and its payload (in general the whole
IP payload) within a UDP packet destined to the well-known port IP payload) within a UDP packet destined to the well-known port
GUT_P. Unfortunately, it requires user-space TCP, for which there is GUT_P. Unfortunately, it requires user-space TCP, for which there is
not a readily available implementation, and creating one is a large not a readily available implementation, and creating one is a large
project in itself. This draft has expired and its future is still project in itself. This draft has expired and its future is still
not clear as it has not yet been adopted by a working group. not clear as it has not yet been adopted by a working group.
B.1.1.4. UPnP IGD B.1.1.4. UPnP IGD
Universal Plug and Play Internet Gateway Devices (UPnP IGD) sit on Universal Plug and Play Internet Gateway Devices (UPnP IGD) sit on
skipping to change at page 88, line 28 skipping to change at page 88, line 28
to communicate with it. to communicate with it.
Many NATs do not support PMP. In those that do support it, it has Many NATs do not support PMP. In those that do support it, it has
similar issues with negotiation of multilayer NATs as UPnP. Video similar issues with negotiation of multilayer NATs as UPnP. Video
conferencing is used extensively in enterprise networks, and NAT PMP conferencing is used extensively in enterprise networks, and NAT PMP
is not generally available in enterprise-class routers. is not generally available in enterprise-class routers.
B.1.1.6. SCTP B.1.1.6. SCTP
It would be quite straight forward to specify a BFCP binding for SCTP It would be quite straight forward to specify a BFCP binding for SCTP
[26], and then tunnel SCTP over UDP in the use case described in [27], and then tunnel SCTP over UDP in the use case described in
Appendix B.1. SCTP is gaining some momentum currently. There is Appendix B.1. SCTP is gaining some momentum currently. There is
ongoing discussion in the RTCWeb WG regarding this approach. ongoing discussion in the RTCWeb WG regarding this approach.
However, this approach for tunneling over UDP was not mature enough However, this approach for tunneling over UDP was not mature enough
when considered and not even fully specified. when considered and not even fully specified.
B.1.1.7. BFCP over UDP transport B.1.1.7. BFCP over UDP transport
To overcome the problems with establishing TCP flows between BFCP To overcome the problems with establishing TCP flows between BFCP
entities, an alternative is to define UDP as an alternate transport entities, an alternative is to define UDP as an alternate transport
for BFCP, leveraging the same mechanisms in place for the RTP over for BFCP, leveraging the same mechanisms in place for the RTP over
UDP media streams for the BFCP communication. When using UDP as the UDP media streams for the BFCP communication. When using UDP as the
transport, it is recommended to follow the guidelines provided in transport, it is recommended to follow the guidelines provided in
[24]. [25].
Minor changes to the transaction model are introduced in that all Minor changes to the transaction model are introduced in that all
requests now have an appropriate response to complete the requests now have an appropriate response to complete the
transaction. The requests are sent with a retransmit timer transaction. The requests are sent with a retransmit timer
associated with the response to achieve reliability. This associated with the response to achieve reliability. This
alternative does not change the semantics of BFCP. It permits UDP as alternative does not change the semantics of BFCP. It permits UDP as
an alternate transport. an alternate transport.
Existing implementations, in the spirit of the approach detailed in Existing implementations, in the spirit of the approach detailed in
earlier versions of this draft, have demonstrated this approach to be earlier versions of this draft, have demonstrated this approach to be
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