See comments inline...
Greger V. Teigre wrote:
Have a look at: http://www.iptel.org/ser/doc/modules/html/usrloc.html#AEN153
Synchronization *to* a DB works of course out of the box (needed for saving locations).
But for clustering you will need to synchronize your memory *from* the DB or from the memory of the other nodes on the fly to get locations from other nodes so you can lookup them again.
Locations are not really that critical, are they? If you use registration intervals of ex. 10 minutes, how do you even manage to synchronize the databases manually?
We've about 20.000 users, which would result in ~2.900.000 successful registrations per day or ~35 successful registerations per second, and that means ~70 register messages per second (because of the www_challenge).
Replicating on SIP layer means that every successful REGISTER has to be sent to every server, so IMHO this just will not scale.
Cheers, Andy