Technical Tip: Verifying the MTU Used by OSPF Neighbors for Database Exchange

[acvaldez]

Description	This article describes how to verify MTU in OSPF Neighborship During Database Exchange Using Wireshark.
Scope	FortiGate OSPF.
Solution	Run a packet capture on the FortiGate for the neighbor IP address (100.100.100.100): diag sniff packet any ‘host 100.100.100.100 and port 89’ 6 0 a Convert the captured packet data using the following guide: Technical Tip: How to import 'diagnose sniffer packet' data to WireShark Open the converted pcap file in Wireshark and apply the filter: ospf.db.interface_mtu In the packet header, expand the following: Open Shortest Path First (OSPF) section. Expand DB Description. The MTU value used will be visible in this section.