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OSPF Neighborship Fail - MTU too large
03/26/2020 9 13386
Impossible to create OSPF neighborship with DR and DBR.
Log Monitor show:
OSPF:RECV[DD]: From 10.189.189.254 via X2:10.189.189.245: MTU size is too large (1500)
OSPF:RECV[LS-Ack]: From 10.189.189.251 via X2:10.189.189.245: State is less than Exchange
The root cause is the MTU size on the interface X2.
- Please set the MTU to 1500:
- Go to Network | Interfaces and configure the interface (i.e. X2 Interface)
- In the tab Advanced, change the Interface MTU to 1500 and click OK.
N.B. If your SonicWall is a GEN 5 and the interface is not in the WAN zone, please read the following article to make this change: How to change the MTU value of a non-WAN Interface on Gen 5