I've gone through the following documents, and I'm just struggling with my best available options for adding HA to an existing CGN implementation. There are no VRFs in the existing implementation. I have two edge routers(ASR1002) which are meshed to my two "NAT routers"(ASR1004) which then are meshed to a pair of 6504s in a VSS configuration. It seems every option revolving around CGN and B2B has some caveat that inhibits me from utilizing some form of redundancy for CGN.
Realistically should this document be what I'm needing to solve this problem? It seems like it, but I'm not using VRFs currently and the dealbreaker is if I have ECMP I can't guarantee that return traffic will hit the same NAT router - breaking the symmetrical routing. Which the restrictions for box-to-box state that asymmetric routing with B2B and CGN is not supported.
https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipaddr_nat/configuration/xe-3s/nat-xe-3s-book/iadnat-vrf-aware-b2b-ha.html
https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipaddr_nat/configuration/xe-3s/nat-xe-3s-book/iadnat-cgn.pdf
Any guidance or input would be greatly appreciated.
