[c-nsp] Cisco 4900M and Layer2 Broadcasts

[Ivan]

I am hoping someone may have come across an issue I am seeing on a Cisco 
4900M running 15.1(2)SG3.

I have a device connected to an interface sending traffic from it's own 
MAC address to MAC address ff:ff:ff:ff:ff:ff.  When the layer 3 protocol 
is IPv6 I see this going out other port in the same vlan as the source - 
all good.  When the layer 3 protocol is IPv4 the frames seem to go into 
a black hole - very bad.  I have confirmed all this with packet captures.

I have poked around but cam find any indication of the issue.  I will be 
logging a TAC case in the next day or two for this but would be 
interested to hear if anyone else has seen this.

Thanks

Ivan

PS.  Not really looking to get into the details of the connected devices 
etc - just some HA type traffic using layer 2 over a vlan.