Hi,
We have recently deployed replacement VOIP solution, replacing our analogue system.
This system is being routed via our firewall cluster and have noticed a number of things, like IPS blocks. Those have been dealt with but we are still getting a large amount of dropped packets, due to "Re-invites exceed the limit", as detailed below.
VoIP calls are dropped with "SIP Re-Invites exceeded the limit" Reject Reason
We initially changed the mac invites limit from the default of 30 to 100 but all this has done is pushed out the period in which this event happens. We also reduced the SIP expiry from the default of 66 to 50 and now 40 but this again has simply pushed out the period in between events.
I don't know what is considered a "sensible" or "healthy" setting for either of those two values, as in can the expiry be too short or the maximum invites be too high.
The other option is to change the defined service and set its protocol to "None", which I have not yet done. Having the SIP traffic being inspected seems like a good idea, protection from call hijacking being one benefit.
There has been no observeable issue with these events happening though, but its something for us to continue to look into, I feel.
Howard