Good afternoon, i'm having a problem with MTU with my PPPoE Clients.
If i try to ping them with size=1500, i get a "Timeout" reply.
If i try with size=1600 i get "fragmentation needed and DF set".
If i try with size=1300 i can ping without problem.
There seems to be a blackhole problem, doing tests with a Windows PC i discoveder that the "Timeout" reply appear only in the range of 1453-1472 Bytes. If it's greater i get "fragmentation needed", if it is inferior i can ping.
Also, i see that the error presents only if the PPPoE Server is configured outside my BGP router...
OK) [BGP] --------- [CCR + PPPoE Server]----- [PPPoE Client]
Always get a reply (frag needed or ping).
NOT OK) [BGP] -------- [CCR] ----- [Another CCR + PPPoE Server] ----- [PPPoE Client]
I get "timeout" in the 1453-1472 range like i described above.
Doesn't matter if i change MTU/MRU values on PPPoE server, i alway get the problem.
Every link is ethernet with default MTU 1500.
I tried with ROS version 6.34.6, 6.38.7, 6.40.9 and 6.42.7, nothing change...
I don't understand where is the problem. Help pls!