Hello,
I am troubleshooting a multivendor solution over alu, cisco, and juniper where all but the ALU are set to the default MTU (1500+vendor overhead inclusion), the ALU is set to 1540. I have a router inserting into the alu ring trying to reach another router several hundred miles away. Pings over this virtual circuit succeed up to 1470 out of the router or a host off of the router, but anything above fails.
At mimium 1500 should succeed. I am curious what kinds of issues can cause a sub-MTU frame/packet to fail. OAM tests on the ALU demonstrate successful traffic up to 1540.
I should add that other virtual circuits with this same configuration over the same core elements are operating fine. I can only imagine this to be a physical layer issue.
