[SunRescue] LAN Commmunication (was Sparc 10 cover plates)

Tim Hauber Tim_Hauber at STEV.net
Wed Dec 22 14:24:17 CST 1999

rescue at sunhelp.org,Internet writes:
>"background" traffic increase when the amount of hosts increase.
>But, imagine in a switched LAN with multiple repeaters, switches,
>bridges, mediaconverters and all such things, they can't get rid of
>"all" traffic either, no?
>I was just thinking of when I was at one of our customers site, where
>they have hosts in the amount of "thousands". They sure is connecting
>through switches, but what I came to notice was that it was a huge
>amount of broadcast packets?
>I mean, imagine a WinNT network where EVERY machine thinks it needs to
>know EXACTLY where every machine is, it's status, it's wifes name, it's
>social security number, the color of your dogs eyes and so on - this
>must be a problem. Just "keeping up" the LAN is almost rendering itself
>You can't exactly add just more switches and increase segements, cause
>you'd still have these broadcasts running through to every segment
>available everywhere, right?
>Not that we are talking much bandwidth or huge packets, but a sum of
>packets fairly spread, just enough to make a collision sound like a
>normal everyday happening.
>I just hate it when I plug in a freshly installed server, not even
>booted, into a switch and see the blinkenlichts starts to glow - without
>even having any traffic.

yeah, NT seems to like to talk a lot, primarily because it is designed to
be as dynamic as posibble, so every machine on the network has to get all
of it's identity information from the server (assuming the network is set
up with WINS etc.) and then periodically let the server(s) know it is
still there, which leads to a lot of overhead and broadcast packets.  I
don't regularly work on Windows networks, but Appletalk is similar, in
that the machines do a lot of chattering to establish what is on the
network.  Any network runs better if you disable everything you aren't
using, and run static as much as possible.  Networks that live behind
firewalls and use fake IP numbers can go completely static, which adds to
setup time, but can shorten troubleshooting time.  In our school all our
machines have static IP numbers (using the 10.x.x.x private range) which
indicate the type of machine, whether it is a student,teacher, or
administrative machine, what OS it runs, what room number, and which
machine in the room.  Makes tracking down network anomalies a piece of
cake, look at the IP number and you know which machine it is, without
referring to any lists or anything.  It also eliminates any DHCP traffic
from the machines.  The difference shows on the blinkenlights on the hubs

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