tcp/ip & fddi chips (was Re: binary Mach distribution for 386)

[Steve Blair]

[the following are *MY* opinions, and >not< DELL's]


Having recently left a networking company in Ca., I spent
about 4 months working with FDDI. A few observations that
I observed while working with several FDDI TCP/IP implementations:

1) the only way almost anyone will every get close to 100Mb's/sec
	is if nothing is running on the network, and TCP/IP doesn't
	exist.
2) TCP/IP over FDDI was only successful in gaining a B/W of about
	45->60Mb's/sec in "normal" operation mode, and in "burst"
	mode, mabye about 65->72Mb's/sec.
3) TCP/IP is notoriously ineffecient as a statefull protocol on
	"any wire". Therefore, that's one of the reasons that on
	a fairly quiet network, you'll only see about 4->6.2Mb's/sec
	*due to the statefull overhead* of TCP/IP.


FDDI does/will add significantly to the networked performance of many
systems, and applications that are written to take advantage of the
increased bandwidth. However, there are other mitigating issues that
can(*and do*) hamper effeciency on a network(FDDI). Some of these
issues are:


1) not all vendors are racing to adopt/implement FDDI  until the
	marketing/compatibality  issues are "wrung out".
2)  FDDI has certain information that in restructuring the "ring":
	after a failure takes sometime to occur. Also there are
	other packets, like scrubber packets, that consume some
	network overhead, just like routing information does.

Hopefull this will help. *YOUR MILEAGE WILL VARY*

steve blair	DELL	UNIX	DIVISION