I have an issue where data being routed through a 6500 sup720 is using its interface mac as the source, rather than the virtual.
ARP to the virtual IP respond with the virtual MAC, however.
ICMP request originating from network 5 (VLAN5) are routed to network 111, and once the ethernet header leaves the 6500, it has the interface mac. The reply, coming into the 6500, is now using the interface mac, rather than the HSRP virtual.
Redirects are disabled on the HSRP interfaces.
This is all part of a much bigger issue that we are experiencing, but this is a clue to why we may be having this problem.