I have worked for days on a problem with MPLS and VPLS.

I have 5 routers in a row. each router has a VPLS tunnel from router 1.
I can ping a 1500 byte packet thru to all the routers except to router 3.
I assume my MPLS settings are correct for MTU or else the 1500 byte packets would not get thru to routers 4 or 5.
The max size packet is 1478 to router 3.

Im pulling all the little hair I have left out.
Seems to have started after a router upgrade to 5.12 from 5.7 and 5.13 was no better.

Anyone have any ideas??

Funny thing is Its an OSPF ring, if I reroute the traffic around router 2, 1500 byte packets work to router 3!

Funny thing is Its an OSPF ring, if I reroute the traffic around router 2, 1500 byte packets work to router 3!

Sorry, I'm not of much help,
but with exactly the same problem. In my case a RB1100, still FW 5.5

http://forum.mikrotik.com/viewtopic.php?f=14&t=59244

saludos
Bernardo