draft-ietf-sipcore-reinvite-02.txt   draft-ietf-sipcore-reinvite-03.txt 
SIPCORE G. Camarillo, Ed. SIPCORE G. Camarillo, Ed.
Internet-Draft C. Holmberg Internet-Draft C. Holmberg
Updates: 3261 (if approved) Ericsson Updates: 3261 (if approved) Ericsson
Intended status: Standards Track Y. Gao Intended status: Standards Track Y. Gao
Expires: September 5, 2010 ZTE Expires: September 5, 2010 ZTE
March 4, 2010 March 4, 2010
Re-INVITE and Target-refresh Request Handling in the Session Initiation Re-INVITE and Target-refresh Request Handling in the Session Initiation
Protocol (SIP) Protocol (SIP)
draft-ietf-sipcore-reinvite-02.txt draft-ietf-sipcore-reinvite-03.txt
Abstract Abstract
In this document, we clarify the handling of re-INVITEs in SIP. We In this document, we clarify the handling of re-INVITEs in SIP. We
clarify in which situations a UAS (User Agent Server) should generate clarify in which situations a UAS (User Agent Server) should generate
a success response and in which situations a UAS should generate an a success response and in which situations a UAS should generate an
error response to a re-INVITE. Additionally, we clarify issues error response to a re-INVITE. Additionally, we clarify issues
related to target-refresh requests. related to target-refresh requests.
Status of this Memo Status of this Memo
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Re-INVITE Handling . . . . . . . . . . . . . . . . . . . . . . 4 3. Re-INVITE Handling . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Background on Re-INVITE Handling by UASs . . . . . . . . . 4 3.1. Background on Re-INVITE Handling by UASs . . . . . . . . . 4
3.2. Problems with Error Responses and Already-executed 3.2. Problems with Error Responses and Already-executed
Changes . . . . . . . . . . . . . . . . . . . . . . . . . 8 Changes . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.3. UAS Behavior . . . . . . . . . . . . . . . . . . . . . . . 9 3.3. UAS Behavior . . . . . . . . . . . . . . . . . . . . . . . 9
3.4. UAC Behavior . . . . . . . . . . . . . . . . . . . . . . . 10 3.4. UAC Behavior . . . . . . . . . . . . . . . . . . . . . . . 10
3.5. Glare Situations . . . . . . . . . . . . . . . . . . . . . 10 3.5. Glare Situations . . . . . . . . . . . . . . . . . . . . . 11
3.6. Example of UAS Behavior . . . . . . . . . . . . . . . . . 11 3.6. Example of UAS Behavior . . . . . . . . . . . . . . . . . 11
3.7. Example of UAC Behavior . . . . . . . . . . . . . . . . . 14 3.7. Example of UAC Behavior . . . . . . . . . . . . . . . . . 14
3.8. Clarifications on Cancelling Re-INVITEs . . . . . . . . . 16 3.8. Clarifications on Cancelling Re-INVITEs . . . . . . . . . 16
4. Target-refresh Handling . . . . . . . . . . . . . . . . . . . 17 4. Target-refresh Handling . . . . . . . . . . . . . . . . . . . 17
4.1. Background on Target-refresh Requests . . . . . . . . . . 17 4.1. Background on Target-refresh Requests . . . . . . . . . . 17
4.2. Clarification on the Atomicity of Target-Refresh 4.2. Clarification on the Atomicity of Target-Refresh
Requests . . . . . . . . . . . . . . . . . . . . . . . . . 17 Requests . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.3. UAC Behavior . . . . . . . . . . . . . . . . . . . . . . . 18 4.3. UAC Behavior . . . . . . . . . . . . . . . . . . . . . . . 18
4.4. UAS Behavior . . . . . . . . . . . . . . . . . . . . . . . 18 4.4. UAS Behavior . . . . . . . . . . . . . . . . . . . . . . . 18
4.5. Race Conditions and Target Refreshes . . . . . . . . . . . 19 4.5. Race Conditions and Target Refreshes . . . . . . . . . . . 19
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The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"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 RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
UA: User Agent. UA: User Agent.
UAC: User Agent Client. UAC: User Agent Client.
UAS: User Agent Server. UAS: User Agent Server.
Note that the terms UAC and UAS are used with respect to an INVITE
or re-INVITE transaction and do not necessarily reflect the role
of the UA concerned with respect to any other transaction, such as
an UPDATE transaction occurring within the INVITE transaction.
3. Re-INVITE Handling 3. Re-INVITE Handling
The following sections discuss re-INVITE handling. The following sections discuss re-INVITE handling.
3.1. Background on Re-INVITE Handling by UASs 3.1. Background on Re-INVITE Handling by UASs
A UAS receiving a re-INVITE will need to, eventually, generate a A UAS receiving a re-INVITE will need to, eventually, generate a
response to it. Some re-INVITEs can be responded to immediately response to it. Some re-INVITEs can be responded to immediately
because their handling does not require user interaction (e.g., because their handling does not require user interaction (e.g.,
changing the IP address where a media stream is received). The changing the IP address where a media stream is received). The
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