Unexpected Call Failures during physical network failure

Question

Our layout:
We have a private network for Mediation Server<->PSTN Gateway traffic.  (This is a legacy that we are moving away from.)
We have a multi-node FE Pool.  The FE Pool has redundant "corp" NICs using Windows Teaming (~failover) that serves clients and our SIP trunk, but a single NIC to the private network for the PSTN Gateway traffic.
The Mediation Seervice is listening on both "corp" and "pstn" NICs.
What happened:
The PSTN network cable for ONE of the mediation servers ("LyncFE1") was cut inadvertently.
The experience:
Approximately 5 minutes after the cable was cut, "LyncFE1" recognized all gateways were offline. (expected)
Users did not lose connectivity to the server, as the "corp" NICs were unaffected. (expected)
Inbound calls routed around the failure, as the PSTN gateways are configured to do. (expected)
Outbound calls for an indeterminate group of people would fail consistently with 503 errors and the logs clearly indicated no routes available.  These users were not all hosted on LyncFE1 (per a get-csuserpoolinfo of some of the affected users).
 (NOT expected)
I expected that the Mediation Service on "LyncFE1" would recognize that it had no routes, that other servers (let's say "LyncFE2") did have available routes, and that it would then route outbound calls to the other servers via the "corp"
NIC.
Thoughts?

Answer 1

Hi,
 As the available route is associated with Lync client policy. So If you want to use the other route, you need to associate these users client policy with those route using Lync Server Control Panel or Lync Server Management Shell.
Best Regards,
Eason Huang
Eason Huang
TechNet Community Support