[Devel] Processing REGISTER requests

[Dan Pascu]

On Monday 03 October 2005 21:01, Daniel-Constantin Mierla wrote:
> Hello,
>
> the call-id is not reliable, as the rfc says "SHOULD", I also checked

It doesn't matter how reliable is. The whole point of my proposal was to 
improve the behavior for those phones that respect this recommendation 
and keep the current behavior for those that don't. I didn't propose that 
we replace the current lookup-by-contact with lookup-by-callid, I 
proposed to use the 2 together to improve the accuracy.

And as a matter of fact 98% of the phones implement this recommendation 
which means it would improve behavior for 98% of the cases. I'd say it's 
reliable enough to worth it.

> that the sip phones usually uses the same call-id, but in the case of a
> sipphone crash, upon restart/reboot you will get another SIP id, which,

This is not even an example against using callid. If the phone crashed/is 
restarted it will have a new callid indeed but most likely the same 
contact and because we use callid together with contact in the lookup we 
will correctly identify the usrloc entry even across restarts/crashes.

Now even if we assume it wouldn't identify them correctly (but it does) 
still this is a marginal behavior not the rule. How many times does a 
phone crash or is restarted in a row? 5? 10? 20? Then if both callid and 
contact are changed you end up with 20 records in usrloc for the 
registration period. This happens so rarely I don't care.
But currently I have phones that because of broken NATs have 200 contacts 
in my database 24/7 for a single phone. 20 contacts on occasion do not 
bother me. 200 all the time do.

> indeed, should be a new registration, but looking from user's point of
> view is an update. I think that is the reason the RFC keeps "SHOULD"

It will be an update, because failing callid match it will use contact 
match which will succeed.

> there, although would have been more convenient to be "MUST".
>
> There is a draft which adds an extension to identify the devices:
> http://www.softarmor.com/wgdb/docs/draft-jennings-sipping-instance-id-0
>1.txt
>
> It will be added when after the release.

That's very nice, but I don't think this will fix the 200 contacts 
problem, or any other of the mentioned problems, since this draft is 
currently not implemented by any phone.
And in 2 years from now I don't think that more than 40% of phones will 
use this.

The point is to improve behavior with existing phones and alleviate 
current problems. Using callid together with contact can do this right 
now and as phones will start implementing that draft (which may take a 
long time) they will benefit from that solution which will be even 
better. But I don't see any of these mutually exclusive, so why shouldn't 
we use all of them together if they can improve things?

>
> Cheers,
> Daniel


-- 
Dan