[HECnet] FDDI advice

[Paul_Koning at Dell.com]

On Oct 11, 2013, at 1:55 PM, Sridhar Ayengar <ploopster at gmail.com> wrote:

Paul_Koning at Dell.com wrote:
Half duplex Ethernet slows down when there are collisions, but there
is no wait to transmit whenever the link is idle.   With FDDI, there
is (you wait for the token).   So at high load, half duplex Ethernet
might be a little slower than FDDI, but at modest load, it will
definitely be faster (lower latency).

But, doesn't the GIGAswitch get around that by generating a token for each port?   Isn't that how switched-FDDI works?

On token LANs there's a token per LAN.   Yes, if you bridge token LANs, each LAN has its own token.   That's true for all bridges, it's a consequence of what a bridge is.

But still, on any one LAN, the stations have to wait for the token.   That is, unless you have exactly two MACs, and they are DEC stations that support the DEC full duplex mode.   If so, you have no token, and the link operates essentially the same as Ethernet in full duplex mode (except for header format and min/max packet sizes).

	paul