Bill;
> I mean peering speed between a single pair of ISPs at a single
> exchange (or peering) point exceeds that of a single interface.
>
> And, if you need many, say 10, interfaces, l1 have all the
> flexibilities Vadim want.
>
> > Layer 1 peering (or pooling, as it's more usually known) is great for
> > interconnecting fiber networks, fast provisioning, and all that.
>
> You may say that we are not ready for full fiber networking, yet.
>Any given interface is inherently rate limited.
When demand exceeds the capacity, something must be
done. Often this is done w/ "striping" or "muxing"
where multiple "low-speed" channels are "bonded" into
a single virtual path. L1 is not that different than
L2 & L3 in these cases. The specific dynamics are
unique per layer but the problem remains the same.
When l1 is p2p, you can do nothing at l2, unless you additionally
introduce l2 switches which are as expensive as and often slower
(as is the case with ATM) than l3 routers.
But, the point here is that it is not or will not be necessary to
share a single "high-speed" channel for "low-speed" pathes
to multiple ISPs through L2 switches.
Masataka Ohta