Our ISP at a remote site suffered an outage. When the link came backup it brought down our core link. The ISP responsible for the remote site forgot to configure l2pt protocols which resulted in the core link recieveing encapsulated packets on their link which cause it to shut. The remote site ISP have now resolved this problem, but now the core link receives more than 256 mac addresses which shuts the link. We dont know where the problem is and both ISP are saying it is not their problem. The mac addresses are in our network and legitmit, but why all of the sudden is this happening. We have not added any new devices to our network. we have a Layer 2 design would like some pointers if possible.