draft-ietf-mmusic-connectivity-precon-05.txt   draft-ietf-mmusic-connectivity-precon-06.txt 
MMUSIC Working Group F. Andreasen MMUSIC Working Group F. Andreasen
Internet-Draft Cisco Systems, Inc. Internet-Draft Cisco Systems
Intended status: Standards Track G. Camarillo Intended status: Standards Track G. Camarillo
Expires: April 27, 2009 Ericsson Expires: September 10, 2009 Ericsson
D. Oran D. Oran
D. Wing D. Wing
Cisco Systems, Inc. Cisco Systems
October 24, 2008 March 9, 2009
Connectivity Preconditions for Session Description Protocol Media Connectivity Preconditions for Session Description Protocol Media
Streams Streams
draft-ietf-mmusic-connectivity-precon-05.txt draft-ietf-mmusic-connectivity-precon-06
Status of this Memo Status of this Memo
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Abstract Abstract
This document defines a new connectivity precondition for the Session This document defines a new connectivity precondition for the Session
Description Protocol (SDP) precondition framework. A connectivity Description Protocol (SDP) precondition framework. A connectivity
precondition can be used to delay session establishment or precondition can be used to delay session establishment or
modification until media stream connectivity has been successfully modification until media stream connectivity has been successfully
verified. The method of verification may vary depending on the type verified. The method of verification may vary depending on the type
of transport used for the media. For unreliable datagram transports of transport used for the media. For unreliable datagram transports
such as UDP, verification involves probing the stream with data or such as UDP, verification involves probing the stream with data or
control packets. For reliable connection-oriented transports such as control packets. For reliable connection-oriented transports such as
TCP, verification can be achieved simply by successful connection TCP, verification can be achieved simply by successful connection
establishment or by probing the connection with data or control establishment or by probing the connection with data or control
packets, depending on the situation. packets, depending on the situation.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Connectivity Precondition Definition . . . . . . . . . . . . . 3 3. Connectivity Precondition Definition . . . . . . . . . . . . . 4
3.1. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.1. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.2. Operational Semantics . . . . . . . . . . . . . . . . . . 4 3.2. Operational Semantics . . . . . . . . . . . . . . . . . . 5
3.3. Status Type . . . . . . . . . . . . . . . . . . . . . . . 4 3.3. Status Type . . . . . . . . . . . . . . . . . . . . . . . 5
3.4. Direction Tag . . . . . . . . . . . . . . . . . . . . . . 5 3.4. Direction Tag . . . . . . . . . . . . . . . . . . . . . . 5
3.5. Precondition Strength . . . . . . . . . . . . . . . . . . 5 3.5. Precondition Strength . . . . . . . . . . . . . . . . . . 6
4. Verifying Connectivity . . . . . . . . . . . . . . . . . . . . 6 4. Verifying Connectivity . . . . . . . . . . . . . . . . . . . . 7
4.1. Media Stream to Dialog Correlation . . . . . . . . . . . . 7 4.1. Media Stream to Dialog Correlation . . . . . . . . . . . . 7
4.2. Explicit Connectivity Verification Mechanisms . . . . . . 7 4.2. Explicit Connectivity Verification Mechanisms . . . . . . 8
4.3. Verifying Connectivity for Connection-Oriented 4.3. Verifying Connectivity for Connection-Oriented
Transports . . . . . . . . . . . . . . . . . . . . . . . . 9 Transports . . . . . . . . . . . . . . . . . . . . . . . . 9
5. Connectivity and Other Precondition Types . . . . . . . . . . 9 5. Connectivity and Other Precondition Types . . . . . . . . . . 10
6. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 6. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
7. Security Considerations . . . . . . . . . . . . . . . . . . . 14 7. Security Considerations . . . . . . . . . . . . . . . . . . . 15
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
9. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . . 15 9. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . . 16
9.1. Changes since -03 . . . . . . . . . . . . . . . . . . . . 15 9.1. Changes since -05 . . . . . . . . . . . . . . . . . . . . 16
9.2. Changes since -02 . . . . . . . . . . . . . . . . . . . . 15 9.2. Changes since -03 . . . . . . . . . . . . . . . . . . . . 16
9.3. Changes since -01 . . . . . . . . . . . . . . . . . . . . 15 9.3. Changes since -02 . . . . . . . . . . . . . . . . . . . . 16
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15 9.4. Changes since -01 . . . . . . . . . . . . . . . . . . . . 16
10.1. Normative References . . . . . . . . . . . . . . . . . . . 15 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
10.2. Informative References . . . . . . . . . . . . . . . . . . 16 10.1. Normative References . . . . . . . . . . . . . . . . . . . 16
10.2. Informative References . . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17
Intellectual Property and Copyright Statements . . . . . . . . . . 18
1. Introduction 1. Introduction
The concept of a Session Description Protocol (SDP) [RFC4566] The concept of a Session Description Protocol (SDP) [RFC4566]
precondition in the Session Initiation Protocol (SIP) [RFC3261] is precondition in the Session Initiation Protocol (SIP) [RFC3261] is
defined in [RFC3312] (updated by [RFC4032]). A precondition is a defined in [RFC3312] (updated by [RFC4032]). A precondition is a
condition that has to be satisfied for a given media stream in order condition that has to be satisfied for a given media stream in order
for session establishment or modification to proceed. When the for session establishment or modification to proceed. When the
precondition is not met, session progress is delayed until the precondition is not met, session progress is delayed until the
precondition is satisfied or the session establishment fails. For precondition is satisfied or the session establishment fails. For
skipping to change at page 4, line 5 skipping to change at page 5, line 5
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
3. Connectivity Precondition Definition 3. Connectivity Precondition Definition
3.1. Syntax 3.1. Syntax
The connectivity precondition type is defined by the string "conn" The connectivity precondition type is defined by the string "conn"
and hence we modify the grammar found in [RFC3312] as follows: and hence we modify the grammar found in [RFC3312] as follows:
precondition-type = "conn" | "qos" | token precondition-type = "conn" / "qos" / token
This precondition tag is registered with the IANA in Section 8. This precondition tag is registered with the IANA in Section 8.
3.2. Operational Semantics 3.2. Operational Semantics
According to [RFC4032], documents defining new precondition types According to [RFC4032], documents defining new precondition types
need to describe the behavior of UAs (User Agents) from the moment need to describe the behavior of UAs (User Agents) from the moment
session establishment is suspended due to a set of preconditions, session establishment is suspended due to a set of preconditions,
until it is resumed when these preconditions are met. An entity that until it is resumed when these preconditions are met. An entity that
wishes to delay session establishment or modification until media wishes to delay session establishment or modification until media
skipping to change at page 4, line 29 skipping to change at page 5, line 29
the connectivity precondition has been met (i.e., until media stream the connectivity precondition has been met (i.e., until media stream
connectivity has been established in the desired direction or connectivity has been established in the desired direction or
directions). The delay of session establishment defined here implies directions). The delay of session establishment defined here implies
that alerting of the called party does not occur until the that alerting of the called party does not occur until the
precondition has been satisfied. precondition has been satisfied.
Packets may be both sent and received on the media streams in Packets may be both sent and received on the media streams in
question. However, such packets SHOULD be limited to packets that question. However, such packets SHOULD be limited to packets that
are necessary to verify connectivity between the two endpoints are necessary to verify connectivity between the two endpoints
involved on the media stream. That is, the underlying media stream involved on the media stream. That is, the underlying media stream
SHOULD NOT be cut through. For example, STUN packets SHOULD NOT be cut through. For example, ICE connectivity checks
[I-D.ietf-behave-rfc3489bis], RTP [RFC3550] No-Op [I-D.ietf-mmusic-ice] and TCP SYN and ACK packets can be exchanged on
[I-D.ietf-avt-rtp-no-op] packets and their corresponding RTCP media streams that support them as a way of verifying connectivity.
reports, as well as TCP SYN and ACK packets can be exchanged on media
streams that support them as a way of verifying connectivity.
Some media streams are described by a single 'm' line but, Some media streams are described by a single 'm' line but,
nevertheless, involve multiple addresses. For example, [RFC5109] nevertheless, involve multiple addresses. For example, [RFC5109]
specifies how to send FEC (Forward Error Correction) information as a specifies how to send FEC (Forward Error Correction) information as a
separate stream (the address for the FEC stream is provided in an separate stream (the address for the FEC stream is provided in an
'a=fmtp' line). When a media stream consists of multiple destination 'a=fmtp' line). When a media stream consists of multiple destination
addresses, connectivity to all of them MUST be verified in order for addresses, connectivity to all of them MUST be verified in order for
the precondition to be met. In the case of RTP-based media streams, the precondition to be met. In the case of RTP-based media streams,
RTCP connectivity MAY be verified, but it is not a requirement. RTCP connectivity MAY be verified, but it is not a requirement.
skipping to change at page 6, line 35 skipping to change at page 7, line 31
need not use the same. The following rules guide which connectivity need not use the same. The following rules guide which connectivity
verification mechanism to use: verification mechanism to use:
1. if an explicit connectivity verification mechanism (e.g., ICE) is 1. if an explicit connectivity verification mechanism (e.g., ICE) is
negotiated, the precondition is met when the mechanism verifies negotiated, the precondition is met when the mechanism verifies
connectivity successfully, otherwise connectivity successfully, otherwise
2. if a connection-oriented transport (e.g., TCP) is negotiated, the 2. if a connection-oriented transport (e.g., TCP) is negotiated, the
precondition is met when the connection is established. precondition is met when the connection is established.
3. in other cases, an implicit verification mechanism may be 3. in other cases, an implicit verification mechanism MAY be
provided by the transport itself or the media stream data using provided by the transport itself or the media stream data using
the transport (e.g., RTP No-Op) the transport
4. if none of the above apply, connectivity cannot be verified 4. if none of the above apply, connectivity cannot be verified
reliably and the connectivity precondition will never be reliably and the connectivity precondition will never be
satisfied if requested. satisfied if requested.
This document does not mandate any particular connectivity This document does not mandate any particular connectivity
verification mechanism; however, in the following, we provide verification mechanism; however, in the following, we provide
additional considerations for verification mechanisms. additional considerations for verification mechanisms.
4.1. Media Stream to Dialog Correlation 4.1. Media Stream to Dialog Correlation
skipping to change at page 8, line 32 skipping to change at page 9, line 23
is used to verify connectivity preconditions, the precondition is not is used to verify connectivity preconditions, the precondition is not
satisfied until connectivity has been verified for all the component satisfied until connectivity has been verified for all the component
transport addresses used by the media stream. For example, with an transport addresses used by the media stream. For example, with an
RTP-based media stream where RTCP is not suppressed, connectivity RTP-based media stream where RTCP is not suppressed, connectivity
MUST be ascertained for both RTP and RTCP; this is a tightening of MUST be ascertained for both RTP and RTCP; this is a tightening of
the general operational semantics provided in Section 3.2, which is the general operational semantics provided in Section 3.2, which is
imposed by ICE. Finally, it should be noted, that although imposed by ICE. Finally, it should be noted, that although
connectivity has been ascertained, a new offer/answer exchange may be connectivity has been ascertained, a new offer/answer exchange may be
required before media can flow (per ICE). required before media can flow (per ICE).
RTP No-Op [I-D.ietf-avt-rtp-no-op] enables the sender of an RTP No-Op
payload to verify send connectivity by examining the RTCP report(s)
being returned. In particular, the source SSRC in the RTCP report
block is used for correlation. The RTCP report block also contains
the SSRC of the sender of the report and the SSRC of incoming RTP
No-Op packets identifies the sender of the RTP packet. Thus, once
send connectivity has been ascertained, receipt of an RTP No-Op
packet from the same SSRC provides the necessary correlation to
determine receive connectivity. Alternatively, the duality of send
and receive preconditions can be exploited, with one side confirming
when his send precondition is satisfied, which in turn implies the
other sides recv precondition is satisfied.
The above are merely examples of explicit connectivity verification The above are merely examples of explicit connectivity verification
mechanisms. Other techniques can be used as well. It is however mechanisms. Other techniques can be used as well. It is however
RECOMMENDED that ICE be supported by entities that support RECOMMENDED that ICE be supported by entities that support
connectivity preconditions. Use of ICE has the benefit of working connectivity preconditions. Use of ICE has the benefit of working
for all media streams (not just RTP) as well as facilitate NAT and for all media streams (not just RTP) as well as facilitate NAT and
firewall traversal, which may otherwise interfere with connectivity. firewall traversal, which may otherwise interfere with connectivity.
Furthermore, the ICE recommendation provides a baseline to ensure Furthermore, the ICE recommendation provides a baseline to ensure
that all entities that require probe traffic to support the that all entities that require probe traffic to support the
connectivity preconditions have a common way of ascertaining connectivity preconditions have a common way of ascertaining
connectivity. connectivity.
skipping to change at page 11, line 26 skipping to change at page 12, line 20
Since B's radio bearer is not ready yet, B chooses to be the one Since B's radio bearer is not ready yet, B chooses to be the one
initiating the connection and indicates so with a setup attribute initiating the connection and indicates so with a setup attribute
with a value of active. At a later point, when B's radio bearer is with a value of active. At a later point, when B's radio bearer is
ready, B initiates the TCP connection towards A. ready, B initiates the TCP connection towards A.
Once the TCP connection is established successfully, B knows the Once the TCP connection is established successfully, B knows the
"sendrecv" precondition is satisfied, and B proceeds with the session "sendrecv" precondition is satisfied, and B proceeds with the session
(i.e., alerts the Callee), and sends a 180 (Ringing) response. (i.e., alerts the Callee), and sends a 180 (Ringing) response.
The second example shows a basic SIP session establishment using SDP The second example shows a basic SIP session establishment using SDP
connectivity preconditions and RTP No-Op (the required PRACK connectivity preconditions and ICE (the required PRACK transaction
transaction and some SDP details have been omitted for clarity). The and some SDP details have been omitted for clarity). The message
message flow for this scenario is shown in Figure 2 below. flow for this scenario is shown in Figure 2 below.
A B A B
| | | |
|-------------(1) INVITE SDP1--------------->| |-------------(1) INVITE SDP1--------------->|
| | | |
|<------(2) 183 Session Progress SDP2--------| |<------(2) 183 Session Progress SDP2--------|
| | | |
|<~~~~~ Connectivity check to A ~~~~~~~~~~~~~| |<~~~~~ Connectivity check to A ~~~~~~~~~~~~~|
|~~~~~ Connectivity to A OK ~~~~~~~~~~~~~~~~>| |~~~~~ Connectivity to A OK ~~~~~~~~~~~~~~~~>|
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|<~~~~ Connectivity to B OK ~~~~~~~~~~~~~~~~~| |<~~~~ Connectivity to B OK ~~~~~~~~~~~~~~~~~|
| | | |
|-------------(3) UPDATE SDP3--------------->| |-------------(3) UPDATE SDP3--------------->|
| | | |
|<--------(4) 200 OK (UPDATE) SDP4-----------| |<--------(4) 200 OK (UPDATE) SDP4-----------|
| | | |
|<-------------(5) 180 Ringing---------------| |<-------------(5) 180 Ringing---------------|
| | | |
| | | |
Figure 2: Connectivity precondition with RTP No-Op Figure 2: Connectivity precondition with ICE Connectivity Checks
SDP1: A includes a mandatory end-to-end connectivity precondition SDP1: A includes a mandatory end-to-end connectivity precondition
with a desired status of "sendrecv"; this will ensure media stream with a desired status of "sendrecv"; this will ensure media stream
connectivity in both directions before continuing with the session connectivity in both directions before continuing with the session
setup. Since media stream connectivity in either direction is setup. Since media stream connectivity in either direction is
unknown at this point, the current status is set to "none". A's unknown at this point, the current status is set to "none". A's
local status table (see [RFC3312]) for the connectivity precondition local status table (see [RFC3312]) for the connectivity precondition
is as follows: is as follows:
Direction | Current | Desired Strength | Confirm Direction | Current | Desired Strength | Confirm
-----------+----------+------------------+---------- -----------+----------+------------------+----------
send | no | mandatory | no send | no | mandatory | no
recv | no | mandatory | no recv | no | mandatory | no
and the resulting offer SDP is: and the resulting offer SDP is:
m=audio 20000 RTP/AVP 0 96 a=ice-pwd:asd88fgpdd777uzjYhagZg
a=ice-ufrag:8hhY
m=audio 20000 RTP/AVP 0
c=IN IP4 192.0.2.1 c=IN IP4 192.0.2.1
a=rtpmap:96 no-op/8000
a=curr:conn e2e none a=curr:conn e2e none
a=des:conn mandatory e2e sendrecv a=des:conn mandatory e2e sendrecv
a=candidate:1 1 UDP 2130706431 192.0.2.1 20000 typ host
SDP2: When B receives the offer, B sees the mandatory sendrecv SDP2: When B receives the offer, B sees the mandatory sendrecv
connectivity precondition. B can ascertain connectivity to A ("send" connectivity precondition. B can ascertain connectivity to A ("send"
from B's point of view) by use of the RTP No-Op, however B wants A to from B's point of view) by use of the ICE connectivity check, however
inform it about connectivity in the other direction ("recv" from B's B wants A to inform it about connectivity in the other direction
point of view). B's local status table therefore looks as follows: ("recv" from B's point of view). B's local status table therefore
looks as follows:
Direction | Current | Desired Strength | Confirm Direction | Current | Desired Strength | Confirm
-----------+----------+------------------+---------- -----------+----------+------------------+----------
send | no | mandatory | no send | no | mandatory | no
recv | no | mandatory | no recv | no | mandatory | no
Since B wants to ask A for confirmation about the "recv" (from B's Since B wants to ask A for confirmation about the "recv" (from B's
point of view) connectivity precondition, the resulting answer SDP point of view) connectivity precondition, the resulting answer SDP
becomes: becomes:
m=audio 30000 RTP/AVP 0 96 a=ice-pwd:qrCA8800133321zF9AIj98
a=rtpmap:96 no-op/8000 a=ice-ufrag:H92p
m=audio 30000 RTP/AVP 0
c=IN IP4 192.0.2.4 c=IN IP4 192.0.2.4
a=curr:conn e2e none a=curr:conn e2e none
a=des:conn mandatory e2e sendrecv a=des:conn mandatory e2e sendrecv
a=conf:conn e2e recv a=conf:conn e2e recv
a=candidate:1 1 UDP 2130706431 192.0.2.4 30000 typ host
Meanwhile, B performs a successful send connectivity check to A by Meanwhile, B performs a successful send connectivity check to A by
sending an RTP No-Op packet to A and receiving a corresponding RTCP sending an ICE connectivity check packet to A and receiving the
report. B's local status table is updated as follows: corresponding response. B's local status table is updated as
follows:
Direction | Current | Desired Strength | Confirm Direction | Current | Desired Strength | Confirm
-----------+----------+------------------+---------- -----------+----------+------------------+----------
send | yes | mandatory | no send | yes | mandatory | no
recv | no | mandatory | no recv | no | mandatory | no
Since the "recv" connectivity precondition (from B's point of view) Since the "recv" connectivity precondition (from B's point of view)
is still not satisfied, session establishment remains suspended. is still not satisfied, session establishment remains suspended.
SDP3: When A receives the answer SDP, A notes that confirmation was SDP3: When A receives the answer SDP, A notes that confirmation was
requested for B's "recv" connectivity precondition, which is the requested for B's "recv" connectivity precondition, which is the
"send" precondition from A's point of view. A performs a successful "send" precondition from A's point of view. A performs a successful
send connectivity check to B by sending an RTP No-Op packet to B and send connectivity check to B by sending an ICE connectivity check to
receiving a corresponding RTCP report, and A's local status table B and receiving the corresponding response. A's local status table
becomes: becomes:
Direction | Current | Desired Strength | Confirm Direction | Current | Desired Strength | Confirm
-----------+----------+------------------+---------- -----------+----------+------------------+----------
send | yes | mandatory | yes send | yes | mandatory | yes
recv | no | mandatory | no recv | no | mandatory | no
Since B asked for confirmation about the "send" connectivity (from Since B asked for confirmation about the "send" connectivity (from
A's point of view), A now sends an UPDATE (5) to B to confirm the A's point of view), A now sends an UPDATE (5) to B to confirm the
connectivity from A to B: connectivity from A to B:
m=audio 20000 RTP/AVP 0 96 a=ice-pwd:asd88fgpdd777uzjYhagZg
a=rtpmap:96 no-op/8000 a=ice-ufrag:8hhY
m=audio 20000 RTP/AVP 0
c=IN IP4 192.0.2.1 c=IN IP4 192.0.2.1
a=curr:conn e2e send a=curr:conn e2e send
a=des:conn mandatory e2e sendrecv a=des:conn mandatory e2e sendrecv
a=des:conn mandatory e2e sendrecv
a=candidate:1 1 UDP 2130706431 192.0.2.1 20000 typ host
B has both send and recv connectivity confirmed at this point and the B has both send and recv connectivity confirmed at this point and the
session can continue. session can continue.
7. Security Considerations 7. Security Considerations
In addition to the general security considerations for preconditions In addition to the general security considerations for preconditions
provided in [RFC3312], the following security issues, which are provided in [RFC3312], the following security issues, which are
specific to connectivity preconditions, should be considered. specific to connectivity preconditions, should be considered.
Connectivity preconditions rely on mechanisms beyond SDP such as Connectivity preconditions rely on mechanisms beyond SDP such as
TCP[RFC0793] connection establishment, RTP No-Op TCP[RFC0793] connection establishment, or ICE connectivity checks
[I-D.ietf-avt-rtp-no-op], or STUN [I-D.ietf-behave-rfc3489bis] to [I-D.ietf-mmusic-ice] to establish and verify connectivity between an
establish and verify connectivity between an offerer and an answerer. offerer and an answerer. An attacker that prevents those mechanism
An attacker that prevents those mechanism from succeeding can prevent from succeeding can prevent media sessions from being established and
media sessions from being established and hence it is RECOMMENDED hence it is RECOMMENDED that such mechanisms are adequately secured
that such mechanisms are adequately secured by message authentication by message authentication and integrity protection. Also, the
and integrity protection. Also, the mechanisms SHOULD consider how mechanisms SHOULD consider how to prevent denial of service attacks.
to prevent denial of service attacks. Similarly, an attacker that Similarly, an attacker that can forge packets for these mechanisms
can forge packets for these mechanisms can enable sessions to be can enable sessions to be established when there in fact is no media
established when there in fact is no media connectivity, which may connectivity, which may lead to a poor user experience.
lead to a poor user experience. Authentication and integrity Authentication and integrity protection of such mechanisms can
protection of such mechanisms can prevent this type of attacks and prevent this type of attacks and hence use of it is RECOMMENDED.
hence use of it is RECOMMENDED.
It is also strongly RECOMMENDED that integrity protection be applied It is also strongly RECOMMENDED that integrity protection be applied
to the SDP session descriptions. S/MIME [RFC3853] provides such end- to the SDP session descriptions. S/MIME [RFC3853] provides such end-
to-end integrity protection, as described in [RFC3261]. to-end integrity protection, as described in [RFC3261].
8. IANA Considerations 8. IANA Considerations
IANA is hereby requested to register a new precondition type under IANA is hereby requested to register a new precondition type under
the Precondition Types used with SIP subregistry, which is located the Precondition Types used with SIP subregistry, which is located
under the Session Initiation Protocol (SIP) Parameters registry. under the Session Initiation Protocol (SIP) Parameters registry.
skipping to change at page 15, line 14 skipping to change at page 16, line 4
8. IANA Considerations 8. IANA Considerations
IANA is hereby requested to register a new precondition type under IANA is hereby requested to register a new precondition type under
the Precondition Types used with SIP subregistry, which is located the Precondition Types used with SIP subregistry, which is located
under the Session Initiation Protocol (SIP) Parameters registry. under the Session Initiation Protocol (SIP) Parameters registry.
Precondition-Type Description Reference Precondition-Type Description Reference
----------------- ----------------------------------- --------- ----------------- ----------------------------------- ---------
conn Connectivity precondition [RFCxxxx] conn Connectivity precondition [RFCxxxx]
[Note to the RFC Editor: replace RFCxxxx with the number assigned to [Note to the RFC Editor: replace RFCxxxx with the number assigned to
this RFC.] this RFC.]
9. Change Log 9. Change Log
9.1. Changes since -03 9.1. Changes since -05
Removed RTP No-Op. Fixed ABNF.
9.2. Changes since -03
Minor fixes here and there. Minor fixes here and there.
9.2. Changes since -02 9.3. Changes since -02
Connectivity preconditions are now mechanism agnostic. Clarified Connectivity preconditions are now mechanism agnostic. Clarified
when and how to use ICE, RTP No-Op, and connection establishment when and how to use ICE, RTP No-Op, and connection establishment
procedures to check connectivity. Clarified relation with other procedures to check connectivity. Clarified relation with other
precondition types. precondition types.
9.3. Changes since -01 9.4. Changes since -01
There are no changes since the previous version of the document. There are no changes since the previous version of the document.
10. References 10. References
10.1. Normative References 10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
skipping to change at page 16, line 9 skipping to change at page 16, line 47
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E. A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261, Schooler, "SIP: Session Initiation Protocol", RFC 3261,
June 2002. June 2002.
[RFC3312] Camarillo, G., Marshall, W., and J. Rosenberg, [RFC3312] Camarillo, G., Marshall, W., and J. Rosenberg,
"Integration of Resource Management and Session Initiation "Integration of Resource Management and Session Initiation
Protocol (SIP)", RFC 3312, October 2002. Protocol (SIP)", RFC 3312, October 2002.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, July 2003.
[RFC3853] Peterson, J., "S/MIME Advanced Encryption Standard (AES) [RFC3853] Peterson, J., "S/MIME Advanced Encryption Standard (AES)
Requirement for the Session Initiation Protocol (SIP)", Requirement for the Session Initiation Protocol (SIP)",
RFC 3853, July 2004. RFC 3853, July 2004.
[RFC4032] Camarillo, G. and P. Kyzivat, "Update to the Session [RFC4032] Camarillo, G. and P. Kyzivat, "Update to the Session
Initiation Protocol (SIP) Preconditions Framework", Initiation Protocol (SIP) Preconditions Framework",
RFC 4032, March 2005. RFC 4032, March 2005.
[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", RFC 4566, July 2006. Description Protocol", RFC 4566, July 2006.
skipping to change at page 16, line 40 skipping to change at page 17, line 28
the Session Description Protocol (SDP)", RFC 4145, the Session Description Protocol (SDP)", RFC 4145,
September 2005. September 2005.
[RFC4960] Stewart, R., "Stream Control Transmission Protocol", [RFC4960] Stewart, R., "Stream Control Transmission Protocol",
RFC 4960, September 2007. RFC 4960, September 2007.
[RFC5027] Andreasen, F. and D. Wing, "Security Preconditions for [RFC5027] Andreasen, F. and D. Wing, "Security Preconditions for
Session Description Protocol (SDP) Media Streams", Session Description Protocol (SDP) Media Streams",
RFC 5027, October 2007. RFC 5027, October 2007.
[I-D.ietf-avt-rtp-no-op]
Andreasen, F., "A No-Op Payload Format for RTP",
draft-ietf-avt-rtp-no-op-04 (work in progress), May 2007.
[I-D.ietf-mmusic-ice] [I-D.ietf-mmusic-ice]
Rosenberg, J., "Interactive Connectivity Establishment Rosenberg, J., "Interactive Connectivity Establishment
(ICE): A Protocol for Network Address Translator (NAT) (ICE): A Protocol for Network Address Translator (NAT)
Traversal for Offer/Answer Protocols", Traversal for Offer/Answer Protocols",
draft-ietf-mmusic-ice-19 (work in progress), October 2007. draft-ietf-mmusic-ice-19 (work in progress), October 2007.
[I-D.ietf-mmusic-ice-tcp] [I-D.ietf-mmusic-ice-tcp]
Rosenberg, J., "TCP Candidates with Interactive Rosenberg, J., "TCP Candidates with Interactive
Connectivity Establishment (ICE)", Connectivity Establishment (ICE)",
draft-ietf-mmusic-ice-tcp-07 (work in progress), draft-ietf-mmusic-ice-tcp-07 (work in progress),
July 2008. July 2008.
[I-D.ietf-behave-rfc3489bis]
Rosenberg, J., Mahy, R., Matthews, P., and D. Wing,
"Session Traversal Utilities for (NAT) (STUN)",
draft-ietf-behave-rfc3489bis-18 (work in progress),
July 2008.
Authors' Addresses Authors' Addresses
Flemming Andreasen Flemming Andreasen
Cisco Systems, Inc. Cisco Systems, Inc.
499 Thornall Street, 8th Floor 499 Thornall Street, 8th Floor
Edison, NJ 08837 Edison, NJ 08837
USA USA
Email: fandreas@cisco.com Email: fandreas@cisco.com
Gonzalo Camarillo Gonzalo Camarillo
Ericsson Ericsson
Hirsalantie 11 Hirsalantie 11
Jorvas 02420 Jorvas 02420
Finland Finland
Email: Gonzalo.Camarillo@ericsson.com Email: Gonzalo.Camarillo@ericsson.com
David Oran David Oran
Cisco Systems, Inc. Cisco Systems, Inc.
skipping to change at page 17, line 42 skipping to change at page 18, line 23
Cisco Systems, Inc. Cisco Systems, Inc.
7 Ladyslipper Lane 7 Ladyslipper Lane
Acton, MA 01720 Acton, MA 01720
USA USA
Email: oran@cisco.com Email: oran@cisco.com
Dan Wing Dan Wing
Cisco Systems, Inc. Cisco Systems, Inc.
170 West Tasman Drive 170 West Tasman Drive
San Jose, CA 94301 San Jose, CA 95134
USA USA
Email: dwing@cisco.com Email: dwing@cisco.com
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