REFER with no Implicit Subscription draft-ietf-sip-refer-with-norefersub-01

1
REFER with no Implicit Subscription
draft-ietf-sip-refer-with-norefersub-01

• By Orit Levin
• oritl_at_microsoft.com

2
REFER with no Implicit Subscription
draft-ietf-sip-refer-with-norefersub-01

• Motivation
• Allow for REFER without creating a dialog and
  automatic subscription to the Dialog event
  package
• Mechanism
• New option tag norefersub is defined and
  registered with IANA
• Forking MUST be prevented (for example, using
  GRUU)
• Status
• Last Called a month ago
• All the comments were incorporated except for the
  new thread from the last week

3
How does REFER-Issuerenables the feature?

• Commonly is preceded by OPTIONS (or other
  previous engagement between the UAs)
• Supported Header in the Request
• REFER-Issuer is willing supporting the feature
  for the particular REFER
• Required Header in the Response
• If the REFER-Recipient chooses to not establish
  the subscription, it includes the tag in the
  Require Header in the response
• Require Header in the Request
• Is used by REFER-Issuer when it mandates using
  the feature for the particular REFER

4
REFER-Issuer suggests using the feature to
REFER-Recipient
REFER- Issuer
REFER- Recipient
REFER- Issuer
REFER- Recipient
REFER (Supported)
REFER (CreateSUB NO)
200 OK (Required)
2xx
Current Draft
Jonathan
5
Should we allow for Require Header usage with
norefersub?
REFER- Issuer
REFER- Recipient
REFER- Issuer
REFER- Recipient
REFER (Required)
REFER (Supported)
420 Bad Extension
2xx
REFER
NOTIFY
481 (Call/Transaction Does Not Exist
200 OK
Current Draft
Cullen
6
The Resolution
7
REFER with no Implicit Subscription Example

• REFER sipcarol_at_chicago.example.com SIP/2.0
• Via SIP/2.0/UDP client.atlanta.example.c
  ombranchz9hG4bKg45
• Max-Forwards 70
• To Carol ltsipcarol_at_chicago.example.comgt
  
• From Alice ltsipalice_at_atlanta.example.co
  mgttag5534562
• Call-ID 849392fklgl43
• CSeq 476 REFER
• Contact ltsipuf313a413_at_example.comgt
• Allow INVITE, ACK, CANCEL, OPTIONS,
  BYE, REFER,
• SUBSCRIBE, NOTIFY
• Accept application/sdp
• Refer-To ltsip3402934234_at_example.comgt
• Supported norefsub, gruu,
• Require norefersub
• Content-Length 0