From: eldho paul (eldho_paul@sify.com)
Date: Wed Jun 15 2005 - 02:14:55 GMT-3
The default system MTU for traffic on the Catalyst 3550 switch is 1500 bytes. You can configure the switch to support frames larger than 1500 bytes by using the system mtu global configuration command. Because the 802.1Q tunneling feature increases the frame size by 4 bytes when the metro tag is added,you must configure all switches in the service-provider network to be able to process maximum frames by increasing the switch system MTU size to at least 1504 bytes
and
If you want to change the mtu in an interface in a router use the command
ip mtu bytes
Quoting john_matus@hotmail.com:
> so is the "protocol" mtu set by the global mtu option? i know from<br>dealing
w/ the 3550 switches that i always have to change the<br>interface mtu to 1500
for ospf adj's to form <since the default is<br>1504 i believe>......
>From: eldho paul <eldho_paul@sify.com>
>To:<br>John Matus <john_matus@hotmail.com>
>CC:<br>ccielab@groupstudy.com
>Subject: Re: system mtu
>Date: Wed, 15 Jun<br>2005 10:31:17 +0500 (IST)
>
> If an IP packet exceeds the MTU set for<br>the interface, the Cisco IOS
>software will fragment it.
>
>All<br>devices on a physical medium must have the same protocol MTU in order<br>
>to<br>operate.
>Regards,
>Eldho.
>
>
>
>
>
>john_matus@hotmail.com:
><br>
> > question regarding mtu on an interface and globally and how the<br>
>2<br>interact
>with each other...
>i think i know part of it but i<br>don't<br>know which direction it works..
>
>is it - if the interface<br>exceeds<br>it's own mtu, then it will fragment
>packets in accordance with the<br>system mtu? or is it the other way
>around....
>or....
>
>is<br>the<br>global mtu the default for all interfaces and the interface mtu<br>
>just<br>
>overrides the global<br>setting?
>
>TIA
>
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