On 10/12/16 12:40 PM, Brett Tate wrote:
Hi,
Since these are B2BUAs, there are *three* different
early dialogs here:
- UAC:B2BUA1
- B2BUA1:B2BUA2
- B2BUA2:UAS
All the rules regarding route sets, etc. apply
separately to each.
I agree. However, I just wanted to mention that the 3gpp specs appear to
be requiring B2BUA Application Servers to add Record-Route instead of
replacing a gruu Contact. I'm not sure how well the 3gpp requirement will
work since nothing has been specified for building (record routing) routes
for use when sending a request to a gruu location.
It always seemed to me that you should't be a UA without putting in your
own Contact URI. But I have scoured 3261 for support for that opinion
and have not found it. So I have (reluctantly) accepted that B2BUAs
using Record-Route to stay in the path while leaving the Contact URI
unchanged are valid.
But Record-Route does cause problems with GRUU. If you aren't careful
you can end up in sub-optimal routing spirals.
A long time ago I worked on some proposals for additions to IMS that
made things work with GRUU. It was complex. And I don't know if that
stuff was ever adopted.
Thanks,
Paul
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