Saturday, September 9, 2017

Determining OSPF.interface mtu byte sizes via a packet capture

When using OSPF, the need can arise to validate the OSPF-interface-value amongst   OSPF neighbors.

If md5 authentication is not deploy the OPSF database descriptor will carry the  OSPF_interface_MTU value in the clear. A tool like  tshark/wireshark will easily display that value.


In a proper OSPF topology all interfaces attached to the LAN would use the same value. By dumping the  OSPF packets you can easily find the  Interface MTU value and ospf neighbors that are not configured correctly.

By using  a packet.capture you can easily  gather statistics without login into numerous routes or devices  for gathering ospf show  collections

Ken Felix
NSE ( network security expert) and Route/Switching Engineer
kfelix  -----a----t---- socpuppets ---dot---com
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