I have 2 router running mpls: 1 RB1100 Ver 4.10 and one RB1000 Ver 4.10, before a receive the rb1100 I was using a rb 450G and the mpls interface was setting in 1522 in both routers. I was working good.

I change de router 450g by a rb1100, and the first problem was some web pages like banks or billings did no open, a change the mpls interface mtu to 1546 a set the Ethernet interface MTU and L2MTU in both router to 1540 and fix the problem open the web pages but, if I try to Ping from my PC to de router with 1500 bytes not respond. the max lengh is 1472.

if I try to ping from other Mikrotik behind de mpls with 1500 bytes respond perfect. and when I try to ping the router before the mpls from my pc with 1500 work perfect too.

Between MPLS Routers I can ping with 1540 bytes perfect.

"[admin@-Fiber] > ping xxx.xxx.162.33 size=1540 do-not-fragment
xxx.xxx.162.33 1540 byte ping: ttl=64 time=3 ms
xxx.xxx.162.33 1540 byte ping: ttl=64 time=3 ms
xxx.xxx.162.33 1540 byte ping: ttl=64 time=2 ms
xxx.xxx.162.33 1540 byte ping: ttl=64 time=2 ms
xxx.xxx.162.33 1540 byte ping: ttl=64 time=2 ms
xxx.xxx.162.33 1540 byte ping: ttl=64 time=2 ms
xxx.xxx.162.33 1540 byte ping: ttl=64 time=2 ms
xxx.xxx.162.33 1540 byte ping: ttl=64 time=2 ms
8 packets transmitted, 8 packets received, 0% packet loss
round-trip min/avg/max = 2/2.2/3 ms
[admin@-Fiber] >


The IGP is ospf and I use the mpls to pass some vpls. and with the 450G was working great.





C:\Documents and Settings\Administrator>ping xxx.xxx.162.33 -l 1500

Pinging xxx.xxx.162.33 with 1500 bytes of data:

Request timed out.

Ping statistics for xxx.xxx.162.33:
Packets: Sent = 1, Received = 0, Lost = 1 (100% loss),

C:\Documents and Settings\Administrator>ping xxx.xxx.162.33 -l 1472

Pinging xxx.xxx.162.33 with 1472 bytes of data:

Reply from xxx.xxx.162.33: bytes=1472 time=29ms TTL=60

Ping statistics for xxx.xxx.162.33:
Packets: Sent = 1, Received = 1, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 29ms, Maximum = 29ms, Average = 29ms

C:\Documents and Settings\Administrator>ping xxx.xxx.162.33 -l 1474

Pinging xxx.xxx.162.33 with 1474 bytes of data:

Request timed out.

Ping statistics for xxx.xxx.162.33:
Packets: Sent = 1, Received = 0, Lost = 1 (100% loss),


C:\Documents and Settings\Administrator>ping xxx.xxx.162.34 -l 1500

Pinging xxx.xxx.162.34 with 1500 bytes of data:

Reply from xxx.xxx.162.34: bytes=1500 time=16ms TTL=61
Reply from xxx.xxx.162.34: bytes=1500 time=17ms TTL=61
Reply from xxx.xxx.162.34: bytes=1500 time=31ms TTL=61
Reply from xxx.xxx.162.34: bytes=1500 time=28ms TTL=61

Ping statistics for xxx.xxx.162.34:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 16ms, Maximum = 31ms, Average = 23ms



I appreciate your help and sorry for my English.

Sounds like MPLS MTU being too low.

I had same problem , set /mpls interface mtu all = 15xx , lets say i set one some nodes to 1526 and on other nodes 1546
when you specify interface mpls mtu its problem.

Juan,

What gear are you using to link the routers? Might be a MTU issue on your gear

No Gino, Es un paso de fibra y el MTU es de 1546, lo probe y no creo que sea esto.

MPLS MTU for running VPLS & MPLS 1546 it's fine.

Perhaps with one RB1000 and one of the end of the fiber and the RB450G at the other end works.

So it's something on the RB1100.00


Right know we have RB1100 ---- RB1000