Symptoms
The command: 'show net cmetric' lists all path MTUs as 0 until the first ICMP Destination Unreachable - Fragmentation Needed (DUFN) message is received.
Impact
There is no impact on traffic. You can see the MTU value using the command 'show net route' instead of 'show net cmetric'.
Note: This working as designed. The MTU value in the metrics is displayed only when ICMP changes the path MTU. Otherwise, it displays 0. You can display the MTU value using the command 'show net route;.
Conditions
-- Run the 'show net cmetric' command to list all path MTUs.
-- The system has not received an ICMP DUFN message.
Workaround
Use 'tmsh show net route' to see the path MTU if a route has MTU set.
