MPSL MTU

Unanswered Question
Sep 11th, 2008

Hi,

I have a question about the mtu size with mpls.

How I set the mtu to support ATOM, VPLS, L3VPN?

I found some documents, but for me it is not totally clear.

It seems that the 12000 Routers sets automatically the mtu to 1538. The 7606, 7201 and 3750 not.

How i configure this on the various platforms?

only set the interface mtu and mpls mtu to 1538bytes (on 3750 the system mtu)?

Brings any drawback if I set, for example, the mtu to 1600 or greater?

Regards,

Thomas

I have this problem too.
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guruprasadr Fri, 09/12/2008 - 01:33

Hi Thomas, [Pls RATE if HELPS]

Below provided are the MTU Configuration Methods on Cisco 7206 & 12000 Series Routers.

Cisco 7206VXR (NPE-G1)

1. Configure MPLS MTU as below:

tag-switching mtu 4470

2. L2 MTU

mtu 1526

Cisco 12404:

1. Configure MPLS MTU as below:

tag-switching mtu 4470

2. L2 MTU

mtu 4470

If i am not wrong, Cisco has introuduced MTU Support of greater than 1500 on Fast Ethernet Interfaces from IOS Versions 12.4(20)T onwards.

Hope I am Informative.

Pls RATE if HELPS

Best Regards,

Guru Prasad R

thomas.feichter Wed, 09/17/2008 - 22:44

Hi,

you say to set the mpls mtu to 4470 ?!

I think to set the MTU/MPLS MTU on all interfaces to 1538..

Are there drawbacks if I set the MTU to a higher value (like 1600 bytes) ?

Regards,

Tom

guruprasadr Thu, 09/18/2008 - 04:45

HI Tom, [Pls Rate if HELPS]

Ethernet line cards support only three queues (up to the 1568-byte size).

Regards,

Guru Prasad R

thomas.feichter Thu, 09/18/2008 - 06:29

Hi,

can you pls explain me this with the "only three queues (up to the 1568-byte size)"?

What does it mean if I use a MTU 4000??

Thanks and regards,

THomas

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