On Thu, 2008-10-23 at 17:05 -0400, Scott Lawrence wrote:
> On Thu, 2008-10-23 at 16:31 -0400, Dale Worley wrote:
> > Currently we generate Call-Ids like this:  s-XXXXXXXXXXXXXXXX-NNN where
> > XXXX is hex for a 64-bit crypto-random number and NNN is a sequence
> > number.  These are nice and short, and if you ignore the XXXX part, it's
> > easy to keep track of which dialog is which, because NNN numbers them
> > for you.
> > 
> > But if you have two federated systems, or dialogs being generated by
> > different components, NNN is no longer unique.  (XXXX is random, so you
> > don't get collisions.)  This makes it harder to trace things.
> > 
> > I was thinking that we can make Call-Ids visibly unique by adopting a
> > technique that is used by many other SIP devices, to append to Call-Ids
> > the address and port of the service:
> > [EMAIL PROTECTED]:pppp.  E.g.,
> > [EMAIL PROTECTED]:5140
> 
> A very very good idea.  I wonder if we really need 64 bits of randomness
> - seems like we could have a reasonable chance to avoid collisions in
> the requisite time window with fewer bits. 

If we append the address/port, we could use fewer uniqueness bits.  It
would shorten messages a bit, though it wouldn't make processing faster,
as we do an MD5 hash for each Call-Id.

Dale


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