I my network I see a very strange behaivour.
I have a chain of 10 device, six are Mikrotik and 4 Cisco.
First is Cisco, in the middle are Mikrotik and at the end Cisco..
Some Vpls beetween Cisco and Cisco work, but Mtu that have on encapsulated traffic isn't 1500 but 1498.
The Vpls are correctly configured and mtu conf are coehrent.
The only strange things is that 1 mirkotik in the middle of network have problem with MTU.
This CCR1072 have 2 interface: 1 to Cisco, 1 to another Mikrotik, and also bridge interface for loopback purpose.
the mtu that I have configured is 1546 but if I try to ping the ip address configured on himself interface receive the error on MTU.
The real mtu are 1500, but on the inerface I have set 1546!
Any idea of this very strange issue?