Problème MTU on MPLS Vrf

[a.auvinet]

Hello,

I realize a laboratory L2 and L3 MPLS VPN.
I use the ME-3800X. I have a problem with the MTU.
PING 1500 byte or more between two host at each end of the network is OK
The VRFs L3 and EoMPLS are almost OK

But the 1500 byte or more of a VLAN interface of ME-3800 to a host outside the MPLS network is not good.
A 64-byte ping is OK.
The backbone-side interfaces have an MTU 1526.

If anyone can help me, I would send you a diagram.

Thank you

[hbruyere]

Bonjour,

Providing configurations and topology in the first message would increase the probability of receiving an answer

Are you having the problem with both eompls and mpls vpn traffic?

Regards,

Herve

[a.auvinet]

Bonjour,

Vous être Françàis ??

Cdlt,

[hbruyere]

Pas exactement, je suis Belge

Cordialement,

Herve

[rsimoni]

Hi,

why don't you use a simpler approach and configure a higher MTU on all links end to end and avoid big headaches calculating the exact size of packets before and after n mpls labels?

ME3800x supports MTU up to 9800 by the way.

On MPLS core interfaces the more MTU the better, that's the golden rule!!! 

Je ne suis pas français non plus, mais je peux vous aider peut-être

Cordialement,

Riccardo

[a.auvinet]

Excuse me for being late.

> why don't you use a simpler approach and configure a higher MTU on  all links end to end and avoid big headaches calculating the exact size  of packets >before and after n mpls labels?

>ME3800x supports MTU up to 9800 by the way.

>On MPLS core interfaces the more MTU the better, that's the golden rule!

This is what I did.

The probleme is not the MTU in the core, The problem is the return of the ping reply that are greater than 1500 bytes.

the interface Vlan of ME-3800X sends a packet of size MTU of outgoing interface tengigabit (MTU1530).

Once arrived  on the LAN, the packet is rejected.

I send you a diagram as soon as possible!!!

For EoMPLS is OK.

One ticket is open at Cisco via my provider NextiraOne

Cordialy,

[rsimoni]

yes, a diagram will definetely help at this stage - a diagram including the MTU value for each interface that is interested in the traffic exchange.

Riccardo