[Serusers] Multiple Registration Servers

Hey All, This is a long email, so please bare with me... Up until now we have used our primary SER serve as both registrar and call routing engine. However, we've recently hit a growth point where the registration load on our servers is high enough that it's affecting our call routing. We currently have about 4,000 IAD's all registering every 5 minutes. This works out to be almost 13.5 regs every second, which in itself is a lot .. If they were sequential. However, at times we will get hundreds of IADs all attempting to register simultaneously (within seconds of each other) and it will keep the server busy for a few moments and cause SIP timeouts on calls that are in the process of being setup. Currently I am using the auth_db module with MySQL for client registration authentication. I believe that the MySQL authentication is what is causing the high load on the server. What I want to do is try to offload the the registrations from our primary routing server, yet, I need the primary server to be stateful of the all registered clients. -or- Find a more efficient way to authenticate client registrations so that the load is not so high. Problem is that most of our customers are home-based VoIP telephone customers behind a Linksys cable/DSL router. So, in order to avoid NAT issues we must have all of our traffic which terminates to the IAD from our PSTN provider come from the same IP address that the the IAD registered from. So I can't use another server and then t_replicate the requests back to the routing server .. Because then the registrar / IP address that will be open on the customers router NAT gateway / firewall will differ from the IP that will terminate the traffic to the IAD from our system. So - my question is .. How do I take load off of the primary server?? Would implementing radius for authentication fix this problem? I am very familiar with radius (using Freeradius) and could easily set this up, but I would prefer not to go to the trouble if it's not going to help with the load. Has anyone else had an issue with client authentication via MySQL and auth_db causing a high load with SER? I am hoping that you fine folks might be able to point me in the right direction. Thanks so much! Darren Nay VoIP Network Development Ionosphere, Inc dnay(a)ionosphere.net