I seem to have a weird issue with ASA 5510 which is actually resolved but would like to share it.
We have a cisco 3745 which has a public LAN port. It has the IP 18.104.22.168/24 ( for example) assigned to one of it's fastethernet interfaces. On this port we have connected an ASA 5510 with public IP 22.214.171.124/24 with default route to 126.96.36.199. Everything works fine when all the internal LAN IPs are globally natted to the outside interface (188.8.131.52).Once we bring in static NATs , they stop to work. For instance if I have a static NAT 10.1.1.3-->184.108.40.206, 10.1.1.3 will not be able to go to internet. Once I remove static NAT, it starts to work.
We came around this issue by enabling some captures on ASA external interface. With static NAT enabled, whenever we try to go out to internet from 10.1.1.3, we saw hits on the capture for traffic from 220.127.116.11 but no returning traffic to 18.104.22.168. So we concentrated on the router, clearing the arp-caches and reloading it but didn't work. We also tried clearing arp tables and nat sessions of ASA. Finally, we just added a static route on the 3745 that goes ip route 22.214.171.124 255.255.255.255 126.96.36.199 and it started to work.
We are confused by this solution as we do not understand why we need to add a static route for resolving the issue when there is already a directly connected route to the 188.8.131.52/24 network. I am not sure if it is a bug with ASA or 3745. We are having a similar issue with ASA 5510 connected to cisco 3825.
We have configured the outside and inside Interface with official ipv6 adresses, set a default route on outside Interface to our router, we also have definied a rule , which also gets hits, to permit tcp from inside Interface to any6.
In Syslog I also se...