[c-nsp] System MTU on trunks for Q in Q

[Mark Tinka]

On Thursday 27 March 2008, Dan Armstrong wrote:

> The reason I don't want to raise it too high - is if
> we're selling TLS services to a customer, (ie a VLAN
> provisioned on 2 ports on different switches, carried
> across our core/trunks) - I don't want them being able to
> send any packet larger than 1500 byes.

You can run Jumbo frames on core-facing interfaces and baby 
giants or standard frames on customer-facing ports.

We do 9,000 bytes in the core and 1,600 toward customers. We 
evaluate customer requests for anything > 1,600 bytes on a 
case-by-case basis.

> I've also never been too clear on the interaction between
> the system mtu command, and the system mtu jumbo command.
>  I've always just made them match...

And the 3560G's we've looked at also have 'system mtu 
routing', which I presume sets the MTU for IP routing 
features, which is a cool feature if your switches 
participate in your OSPF domain but also provide larger 
frame support to customers.

Cheers,

Mark.
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