[nsp] AToM

[Stephen J. Wilcox]

Not all cisco devices/ios's support changing the mtu, even if the cmd is there 
it doesnt mean it necessarily will work.. 

On Tue, 23 Dec 2003, Sergey V. Artjushkin wrote:

> 
> > > But I had a problem with big packets between two PC that was connected
> > > throught trunk port to my cisco devices.
> > 
> > Keep in mind that MPLS normally requires at least 8 bytes extra, and
> > EoMPLS has further encapsulation overhead.
> 
> I know about additional bytes because of VLAN and MPLS tags.
> Let's count the maximum size of the packet.
> One PC sending 1500 bytes to other PC.
> When the packet arrives at the switch, switch adds 4 bytes VLAN tag.
> When packet arrives at the PE router (6509/7401) it adds 8 bytes (2x4 bytes)
> MPLS label tags. So total packet size is 1500 + 4 + 8 = 1512 bytes.
> Right? 
> All input/output ports of the switches was configured with MTU=1540 bytes.
> But big packets didn't reach remote PE. 
> 
> > Steinar Haug, Nethelp consulting, sthaug at nethelp.no
> > 
> 
> 
>