[c-nsp] Layer 2 vs Layer 3 Performance Question

[Jason Luke]

I actually don't know if the linecard has a DFC. It's an old 6509 and keeping any hardware information straight on this proves to be confusing to me.
This is what I have.
L3 Switching Engine II  WS-F6K-PFC2

1000BaseX Supervisor      WS-X6K-SUP2-2GE
Multilayer Switch Feature WS-F6K-MSFC2
Switch Fabric Module      WS-C6500-SFM

When you say "some difference," are we talking significant differences here?  This is basically the singular router for the entire organization (3000+ computers) so EVERYTHING flows through it. If the difference might be 2 or 3 times faster, then its worth it. But if the difference is marginal or a few meg per second, then its kind of irrelevant.

Thanks,
Jason


On 6/22/09 11:40 AM, "Phil Mayers" <p.mayers at imperial.ac.uk> wrote:

>
> So the question is, is there a difference?  I have hundreds of GB's
> to backup so if there is a performance difference one way or the
> other, I would want to know.  The only thing I can see as a
> difference is if I trunk the iSCSI vlan, then the traffic never hits
> the 6509's routing module. Maybe that helps performance?
>

If I've understood you correctly, then there's no difference - the 6500
will forward 1gig layer2 just as quick as 1gig layer3.

There are some possible differences if the linecard does not have a DFC,
or is a bus-linecard and the bus is contended; it would depend on what
other traffic was flowing through the box.