[c-nsp] setting max mtu on switch (Jumbo)

[Gert Doering]

Hi,

On Tue, May 29, 2012 at 04:45:01PM +1030, CiscoNSP_list CiscoNSP_list wrote:
> > You need to ensure that the MTU settings of the layer3 devices connected
> > to the l2 fabric is smaller or equal than the *lowest* L2 MTU of any
> > switch in the fabric.  
> > 
> > If one of the switches has a bigger L2 MTU, that's no problem.
> 
> So If we have an existing 3560 with mtu of 1998, that connects to a 7200 w/NPE400 (10/100 Ints and max mtu of 1500), we should have no issues if we adjust the 3560 MTU to 9000?

The L2 MTU, yes.  The 3560 also has a "routing mtu", and that needs to be
the same value as on the 7200 (1500).

> Is it best practice to set all switches to max mtu?

"Big enough to achieve what you need to achieve".  If all your L3 devices
only use 1500 bps MTU, and no EoMPLS tunneling or whatnot, there is no
real benefit in upping the switch MTU.  There does not seem to be a 
downside either, though.

gert
-- 
USENET is *not* the non-clickable part of WWW!
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Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de
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