[nsp] Fabric-Enabled

[Beprojects.com]

Can anyone enlighten me on what exactly "fabric-enabled" means in terms of
performance/throughput for the following Catalyst 6509 modules?

Catalyst 6500 48-port 10/100/1000 GE Mod., RJ-45  WS-X6148-GE-TX=
Catalyst 6500 48-port fabric-enabled 10/100/1000 Module  WS-X6548-GE-TX=
Catalyst 6500 48-port 10/100/1000 GE Mod: fabric enabled, RJ-45
WS-X6748-GE-TX=

Do you need to be doing L3?

Do you need to have a Fabric Module installed for it to make a difference?

Is this something that you need to "turn-on" or is it just "on" when the
above cards are in the chassis?

I've looked all over their website and can't really find what I'm looking
for as far as descriptions.

On a side note, is there a command that tells you the total throughput
through the Catalyst 6509, either instantaneous, or a 5-minute average?

Thanks.

Peder