Marshal server (MS)

A SIP proxy server which provides:

authentication of users
generates call detail records (CDRs)
provides a entry point for SIP messages into the VOCAL system

⇒ thus the other elements of the VOCAL system don’t need to authenticate each message

monitor heart beats - can uses this for load balancing across RSs
SIP transaction stateful, but not call (dialog) stateful

Allows better scaling, since these servers can be replicated as needed; while allowing the redirect server to focus just on keeping registration information.

Transcript

[slide522] Now, this marshaling server, it basically was just a SIP proxy server. It had these functions. But an important thing to note is it used heartbeats. Everyone knows why you have servers have heartbeats. Do-dum, do-dum, do-dum. It's to tell you you're alive. So the servers exchange heartbeat messages with each other. And so if this marshaling server didn't send a heartbeat to its pair marshaling server, the other marshaling server would assume what? Death. And so it's time to spin up another marshaling server or do something about it. So this idea of being able to have hot standbys or instant instantiate new instances of these things is really useful. But it means we have to think about having heartbeats. And we need to figure out how do we distribute load across the different devices.