You state the LB is sending an ECHO reply with source mac (host A) dest mac (LB) ? That doesnt sound like it is actually responding to the Echo request sent from the source host. Rather it is the Echo Request being looped back. Can you attach a quick...

When you insert the module do you see any errors in the log? Please collect show log last 50 and present any messages specific to the problem. I dont expect much if the module is not recognized then most likely no diagnostics even get a chance to run...

Matt, Can you take a quick sniffer trace of the packet. I am interested to see the destination mac address coming from the Server on ingress to the 4506. The switch may also be redirecting the packet if it has to hairpin the traffic in the same VLAN ...

What type of server is this. Some can learn routes to their gateway. See if you can get a route print or equivalent output. Regards, Dale

Quick question, can you use L3 as an option? Packet rewrite would limit it to the source and dest of the PT-to-PT interfaces? If not, you will want to tunnel it so encap would be the same for every packet. Looking into possible options. Regards, Dale...