- Bronze, 100 points or more
We have around 5 routers in a single LAN where we are running OSPF. The issue is one router we configured the MTU as 1546 bytes but the other routers are configured with 1500 bytes. Initially we had OSPF neighborship issues on the LAN and were getting the logs "OSPF down due to too many retranmissions".
While checking found that the MTU mismatch is the cause of this.
Option is either to configure the same MTU size on all the routers or to configure "ip ospf mtu-ignore". Since we were not able to configure the same MTU we went and configured "ip ospf mtu-ignore" on all the routers post which everything started working fine.
But still we are facing the OSPF neighborship issue couple of times and it comes up automatically. Still getting the same OSPF down due to too many retranmission:"
I would like to know the only solution for the above issue is to have the same MTU size on all the routers?