Hello All,

I am not sure if this is a correct Lync forum but I will try here first.

So here is a short description of Lync 2010 infrastructure and issue I am having.

There is one pool with 4 FEs (with EV) with multiple SBAs deployed. Main issue is that I am getting a lot of errors on SBA regarding the connection from SBA to Gateway on another SBA. Event is a standard one but I will copy paste it to be exact:

One or more Gateways are now marked unavailable.

Gateways:
xxxxxyyyyy@domain.com


Cause: The gateway is unreachable or is responding with same failure response for calls.
Resolution:
Verify that Gateways are functioning and resolve any networking issues.

First step which I did was to telnet this gateway from affected SBA on port 5067 which ended unsuccessfully.

From the same SBA I did telnet 2 another gateways on 2 another SBAs just to rule out that maybe one GW is currently unavailable. This ended with the same negative effect.

In next step I checked the connection between Front End server and those 3 GWs I tested from mentioned SBA. The same telnet on 5067 port. This time I was able to connect successfully on every GW.

So the question is: 

Is the port 5067 needs to opened between SBAs? Is there some kind of heartbeat to check the connectivity between them which generates alert like the one above? 

I was trying to google it but I didn't find a single article about the connection between SBAs. Even Lync Server Firewall Rules app is showing nothing when I set SBA to SBA which I think is not correct.

Thanks for help in advance :)

A user in site A on SBA A could technically be assigned a voice policy that has them make calls through Site B/SBA B.  Even if via policy you configured this never to happen, I'd keep the ports between the devices open, if only to avoid little events like this.