MTU issues for transit traffic and local traffic

Unanswered Question
Dec 23rd, 2007


On my MPLS netwrok that use GSR and OSR routers , MPLS mtu is set to 1550

when i ping from one OSR to other OSR packet larger than 1500 bytes are droped but ping with more than 1500 bytes for trasit traffic is OK

I mean i can ping from one OSR to destinations behind the other OSR with packet size more that 1500

Why this is happening and why this difference exists for transit traffic and local teerminated traffics ?

I have this problem too.
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ashish_gupta Mon, 12/24/2007 - 13:09


Can you give the show interface of the routers coming in between?

MPLS mtu is for the mpls packets to get fragmented when it crosses more than 1550. Anything less than that will not be fragmented. Kindly note this isnt IP mtu but mpls mtu.


Aasheesh Gupta

pooria_koleyni Tue, 12/25/2007 - 22:18

If you tell me which parametres you need about interfaces in between

All traffic are tagged

Transit traffic is ook when i ping with 1500

PIng Localy terminatiing traffic (like Loopbak) wit 1500 fails


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