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199 Status update and open issues draft-ietf-sip-199-02

199 Status update and open issues draft-ietf-sip-199-02. Christer Holmberg. RESOLVED ISSUE #1: Sending 199 reliably. CONCLUSION : Allow sending of 199 reliably, but it may also be sent unreliably even if 100rel has been required. RESOLVED ISSUE #3: SIP information in 199.

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199 Status update and open issues draft-ietf-sip-199-02

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  1. 199Status update and open issuesdraft-ietf-sip-199-02 Christer Holmberg

  2. RESOLVED ISSUE #1:Sending 199 reliably • CONCLUSION: Allow sending of 199 reliably, but it may also be sent unreliably even if 100rel has been required

  3. RESOLVED ISSUE #3:SIP information in 199 • Should the 199 response contain information (SIP headers, final response code etc) from the final response which triggered the 199? • CONCLUSION: The usage of sipfrag in 199 is outside the scope of the draft.

  4. RESOLVED ISSUE #4:199 option-tag • Do we need an option-tag to indicate support of 199, so that 199 is not sent towards UACs not supporting it? • CONCLUSION: • We define an option-tag (”199”). • 199 is not sent unless the UAC has indicated support • We need to clarify usage of the option-tag in Require

  5. OPEN ISSUE #2:UAS sending 199 • Should an UAS be allowed to send 199? • May not be useful for a UA to send 199, but could be useful for B2BUA type-of entities

  6. UAS sending 199:Proposal alternatives • UAS never sends 199 • UAS always sends 199 • UAS sends 199 if forking proxy does not support 199 • UAS sends 199 once procedures have reached a certain state • UAC and UAS negotiate sending of 199 once the early dialog has been established • Other alternatives?

  7. Alt 1: UAS never sends 199 • What about Require: 199?

  8. Alt 2: UAS always sends 199 • Pros • 199 will be sent even if forking proxy does not support 199 • Cons • 199 will be sent even if forking proxy supports 199 • 199 will be sent even in case of no forking – which probably means most of the calls

  9. Alt 3: UAS sends 199 if forking proxy does not support 199 • Pros • 199 will be sent even if forking proxy does not support 199 • Cons • Requires protocol element for proxy to indicate support of 199 • 199 will not be send if forking proxy closest to terminating UAs don’t support 199 • What about Require: 199?

  10. Alt 4: UAS sends 199 once procedures have reached a certain state • Pros • 199 would not be sent until certain actions have taken place on an early dialog • Example: preconditions have been indicated as met • Example: SDP answer has been sent • Can be combined with alternative 3 • Cons • Extensions would have to define at what point 199 would be sent

  11. Alt 5: UAC tells UAS to send 199 when multiple early dialogs have been established (Basically possible already, if the UAC sends Supported: 199 in PRACK/UPDATE) • Pros • UAS will know that forking has occured • UAC can request 199 on a particular dialog based on local resource status • Cons • Extra signalling may be required (unless PRACK or UPDATE is sent for other reasons)

  12. OTHER TO-DOs • Editorial work • Add text to security section • Clarifications • etc • See e-mail from Robert Sparks

  13. THANK YOU!

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