One customer has Cisco Expressway with 2x NIC configured for static NAT option. This gateway is for connecting remote Jabber users to local telephony system. Now we have configured the Peplink Balance to provide high availability for inbound access through DNS delegation. The issue here is that the Expressway has a configuration option to indicate the NAT address. But since we have two ISP connections, this NAT address will change upon ISP switching. What we have noticed, is that if the configured NAT IP address on the Expressway is UP and being used for the inbound connections, everything is working fine. The moment we switch to the other ISP, we noticed that telephone calls get established, but no audio is detected. Have anyone come across this issue? In the meanwhile I will be looking for solutions from the Cisco community as well
In that configuration you have two options I think:
- Use Hosted Fusionhub to bond both WAN links and then send all traffic from the expressway over the VPN tunnel and configure the Static NAT with the public IP of the Fusionhub - this IP then doesn’t change even when WAN links fail and you get packet level resilience for the traffic.
- Use a TURN Relay which is the more traditional approach to this problem (but I haven’t done that before) RFC 5766 - Traversal Using Relays around NAT (TURN): Relay Extensions to Session Traversal Utilities for NAT (STUN)
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