For instance, if the first ATM cell containing a new
IP packet gets lost, the switch may continue to transmit the other 28
cells in the packet even though these are now useless garbage data that
don't need to be forwarded.
There are various hacks at this problem, and to be honest
I haven't payed much attention to them.
The ones I've looked at tend to involve a specially-marked
cell that indicates one or the other end of a packet, or a
train of cells each of which is marked. A switch needing
to discard a cell will attempt to discard all the related
cells, for instance by discarding all cells until an
end-of-packet or start-of-packet or whatever is encountered.
Some of the schemes are even fairly clever about trying to
avoid packet shredding, however none of them are remotely
as clever or as effective at congestion avoidance and
management as RED is.
RED on TCP flows in an ATM switch would impress me.
Sean.