CY13@TE.CC.CMU.EDU.UUCP (01/14/87)
I realize that this question may not be exactly right for this group, but I think that there may have been discussion on this issue in the past -- and I need to be updated. Currently we run a many workstation (300+?) and central fileservers (14) on a single ethernet (right now we can't change this basic configuration). My question revolves around the fileserver connection to the network. Currently we have 14 drop cables going into 2 DELNI's. The question I have is if I tap the fileservers directly onto the ethernet, not using the DELNI's would I gain in performance? Do DELNI's get overloaded? Do they cause increases in network overhead? Any help in this direction would be most helpful, especially if you have had large amounts of data passing through a DELNI. Please send mail to cy13@te.cc.cmu.edu, and I will post a summary. Thank you very much, Curt Yeske -------
dp@JASPER.PALLADIAN.COM.UUCP (01/16/87)
Date: Wed 14 Jan 87 14:12:28-EST
From: C. P. Yeske <CY13@TE.CC.CMU.EDU>
I realize that this question may not be exactly right for this
group, but I think that there may have been discussion on this issue in the
past -- and I need to be updated.
Currently we run a many workstation (300+?) and central fileservers
(14) on a single ethernet (right now we can't change this basic configuration).
My question revolves around the fileserver connection to the network.
Currently we have 14 drop cables going into 2 DELNI's. The question I have
is if I tap the fileservers directly onto the ethernet, not using the DELNI's
would I gain in performance? Do DELNI's get overloaded? Do they cause
increases in network overhead? Any help in this direction would be most
helpful, especially if you have had large amounts of data passing through
a DELNI.
Please send mail to cy13@te.cc.cmu.edu, and I will post a summary.
Thank you very much,
Curt Yeske
-------
delni's provide identical services to trancievers. it is inherent in the definition
of trancievers that they can't run "slower". I suppose there will be a few
nanoseconds propagation delay added by the extra chips, but this should be less than
that added by the 16 meters of wire that you would have to have between the
tranceviers.
again the major thing to watch with delni's (and ther kind: see below) is that the
tranciever cable length's add. thus there are limits to the amount of cascading that
you can do with them (DEC spec's prohibit delni -> delni -> coax connections. as was
mentioned before, such things work in small nets, but when things get bigger, watch
out.)
btw: there is an english firm making a similar box (they call it a fan-out) it is
distributed in this country by Cabletron (in Nashua NH). same number of slots, a
light to show when there is traffic on the net (fun to watch) and about $200 cheaper
than DEC. They also sell trancievers with set of diagnostic (tx rx coll) lights on
them (which helped me find the machine that was occaisonly jamming the net.), a TDR
(time domain reflectometer) that does not require you to power down everything
connected to the net before you can check things, and a tranciever tester. (as always
I have no coneections with cabletron)
<dp>