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No.
You would need if you had an IP MTU mismatch between OSPF neighbors.
I think that the change was only cosmetic, because normally the IP MTU refers to the physical MTU. 

--- Em ter, 2/12/08, Frank Bulk <frnkblk@iname.com> escreveu:

De: Frank Bulk <frnkblk@iname.com>
Assunto: [cisco-bba] 'mtu' versus 'ip mtu'
Para: cisco-bba@puck.nether.net
Data: Terça-feira, 2 de Dezembro de 2008, 7:14

I 'upgraded' from 12.4(19b) to 12.2(SB11)31 this morning and rancid is
showing me that IOS automatically added 'ip mtu 1492' to my interface.


I already had the following in there:
mtu 1492
ip tcp adjust-mss 1452
ppp mtu adaptive

Do I need to set my ip mtu to some other value?

Frank

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Frank,

This is a good reference:
http://www.cisco.com/en/US/docs/ios/12_2sb/feature/guide/newmtu.html

Arie

On Tue, Dec 2, 2008 at 11:14 AM, Frank Bulk <frnkblk@iname.com> wrote:

> I 'upgraded' from 12.4(19b) to 12.2(SB11)31 this morning and rancid is
> showing me that IOS automatically added 'ip mtu 1492' to my interface.
>
> I already had the following in there:
> mtu 1492
> ip tcp adjust-mss 1452
> ppp mtu adaptive
>
> Do I need to set my ip mtu to some other value?
>
> Frank
>
> _______________________________________________
> cisco-bba mailing list
> cisco-bba@puck.nether.net
> https://puck.nether.net/mailman/listinfo/cisco-bba
>

Arie:



Thanks for that reference. There's a lot of talk in there about MPLS MTU,
not so much IP MTU. One sentence jumped out at me:



"A best practice is to set the interface MTU of the core-facing interface to
a value greater than either the IP MTU or interface MTU of the edge-facing
interface."



Since my interface MTU (mtu 1492), is not greater than the IP MTU (ip mtu
1492), doesn't that suggest I should be dropping the value of my ip mtu to
comply with this best practice?



Frank



From: arievayner@gmail.com [mailto:arievayner@gmail.com] On Behalf Of Arie
Vayner
Sent: Tuesday, December 02, 2008 11:24 AM
To: Frank Bulk
Cc: cisco-bba@puck.nether.net
Subject: Re: [cisco-bba] 'mtu' versus 'ip mtu'



Frank,

This is a good reference:
http://www.cisco.com/en/US/docs/ios/12_2sb/feature/guide/newmtu.html

Arie

On Tue, Dec 2, 2008 at 11:14 AM, Frank Bulk <frnkblk@iname.com> wrote:

I 'upgraded' from 12.4(19b) to 12.2(SB11)31 this morning and rancid is
showing me that IOS automatically added 'ip mtu 1492' to my interface.

I already had the following in there:
mtu 1492
ip tcp adjust-mss 1452
ppp mtu adaptive

Do I need to set my ip mtu to some other value?

Frank

_______________________________________________
cisco-bba mailing list
cisco-bba@puck.nether.net
https://puck.nether.net/mailman/listinfo/cisco-bba