[c-nsp] Ethernet Network

Ivan Pepelnjak ip at ioshints.info
Wed Jan 13 02:36:33 EST 2010


The MTU on PA-FE (probably) does not include MAC header and definitely does not include CRC trailer. Otherwise the minimum value of 1500 wouldn't make sense.

> -----Original Message-----
> From: Tony [mailto:td_miles at yahoo.com]
> Sent: Wednesday, January 13, 2010 8:10 AM
> To: cisco-nsp at puck.nether.net; DonnLasher
> Subject: Re: [c-nsp] Ethernet Network
> 
> 
> 
> --- On Wed, 13/1/10, Lasher, Donn <DLasher at newedgenetworks.com> wrote:
> 
> >
> > >> SNIP >>
> > >1500 bytes max data + 22 max header + 4 CRC trailer + 4
> > byte 802.1q tag
> > >+16 up to 4 labels = 1546?
> > >
> > >Why not just enable jumbos and set it as high as
> > possible?
> >
> >
> > 1546 = largest MTU the 355x/356x switches, PA-FE, etc, will
> > support, as
> > I recall.
> >
> 
> PA-FE are limited to 1530. You're correct about 1546 for the switches
> though.
> 
> 7204(config)#int fa4/0
> 7204(config-if)#mtu ?
>   <1500-1530>  MTU size in bytes
> 
> 
> 
> 
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