[c-nsp] Cisco ASA Unicast RPF and GRE

[Ivan]

I suspect my ASA is performing Unicast RPF filtering on the GRE 
encapsulated packets passing through it - i.e. looking into the packet 
that the GRE header is encapsulating.  Has anyone else come across this?

I get the following log message

%ASA-1-106021: Deny GRE reverse path check from x.x.x.x to y.y.y.y on 
interface xxxx

x.x.x.x and y.y.y.y are both directly connected to the ASA and are the 
GRE tunnel source and destination addresses so I don't see how there 
could be any confusion as to where these addresses are.  The addresses 
in the header of the packet that GRE encapsulates is another story and 
thus I suspect the ASA may be looking into the GRE packets payload.

ASA5520 running 7.2

Thanks

Ivan