[SR-Users] [Sems] Solutions to missing BYEs, accounting for them

[Stefan Sayer]

Alex Balashov wrote:
> The B2BUA+SST approach seems clean, efficient, and at least from a 
> theoretical point of view, rather reliable.
clean? I am not so sure any more, trying to hack something together to 
see where this gets. Is there a clean and simple method to do 
re-invite from the b2bua, which catches all the possibilities (changed 
session etc)?

e.g., one possibility, reinvite with last SDP from the other side

A                  b2b                  B
|---INVITE / SDPa-->|                   |
|                   |---INVITE / SDPa-->|
|                   |                   |
|                   |<-- OK/SDPb--------|
|                   |--- ACK ---------->|
|<-- OK/SDPb--------|                   |
|--- ACK ---------->|                   |
|                   |                   |
          ... sst timer expires ...
|                   |                   |
|<--INVITE / SDPb---|                   |
|                   |                   |
|--- OK/SDPc------->|                   |
        now what? ignore that, or do

|                   |---INVITE / SDPc-->|
|                   |<-- OK/SDPd--------|
      one more round of ping-pong?

|                   |                   |

or, other possibility, empty reinvite:
A                  b2b                  B
|---INVITE / SDPa-->|                   |
|                   |---INVITE / SDPa-->|
|                   |                   |
|                   |<-- OK/SDPb--------|
|                   |--- ACK ---------->|
|<-- OK/SDPb--------|                   |
|--- ACK ---------->|                   |
|                   |                   |
          ... sst timer expires ...
|                   |                   |
|<--INVITE          |                   |
|                   |                   |
|--- OK/SDPc------->|                   |
        now what? ignore that, or do

|                   |---INVITE / SDPc-->|
|                   |<-- OK/SDPd--------|
          one more ping-pong?

|                   |                   |

Maybe I just got confused and there is a simple solution?

Stefan

-- 
Stefan Sayer
VoIP Services Consulting and Development

Warschauer Str. 24
10243 Berlin

tel:+491621366449
sip:sayer at iptel.org
email/xmpp:stefan.sayer at gmail.com