[c-nsp] CPE with tracking redundancy and long lived (UDP) nat sessions

[Joe Maimon]

Hey All,

So as is commonly talked about, I have seen a number of end user sites 
with simple redundancy service using IOS routers.

Multiple lines, coulds be the same provider, could be different 
providers, no dynamic routing, different source addresses, uRPF/SAV at 
the provider(s) is to be presumed. CBAC IOS firewall is also in place.

All this with event object tracking with policy routing and nat based on 
egress works just fine EXCEPT.

Long lived NAT sessions, especially the UDP ones dont seem to become 
inactive when the egress changes.

So the VOIP handsets are out of service after either a failover or 
failback. Obviously this is the visible problem symptom.

I have seen this for ICMP as well for continuous pings.

I have in place the workaround of using EEM with clear ip nat trans *

Is there some better way to approach it, other than using dynamic 
routing and routable addresses to eliminate NAT?

c1700-adventerprisek9-mz.124-25b.bin

Thanks in advance. Any and all feedback is most welcome.

Best,

Joe