[PLUG] ethernet switches and glitches

Keith Lofstrom keithl at kl-ic.com
Mon Dec 19 17:18:38 UTC 2005


Are there limits on how many ethernet switches can be placed in series
and still work reliably?  I've run into an interesting problem, and
exceeding some limit might be the cause.

I have computers scattered throughout the house and my home office,
and rather than run big bundles of parallel cat5 everywhere, I tend
to run just a single run of cable then branch out with little ethernet
switch boxes (mostly Linksys 5 port and 8 port units).  From the 
firewall machine to the laptop cables in the kitchen and my wife's
office, there are typically 5 cat5 runs and 4 switches in series between
the firewall and a machine:  (1) Wifi AP/router (2) downstairs switch
(3) upstairs switch (4) room switch.  

(And to anticipate an irrelevant suggestion, no I don't normally leave
the laptops on wifi - the bandwidth is too low for nightly backups, and
it is more secure to send most packets down wires)

Well, the power has been glitching the last few days because of the
wind and the furnace coming on.  About once or twice a day, the upstairs
computers go incommunicado, not talking to each other or to downstairs
and the firewall.  The machines downstairs keep talking to each other
and the net.  I can make the problem go away by power cycling the 
upstairs switches.  About 3 weeks ago I added a new ( brand X ) switch
in a room, but otherwise this setup has worked seemlessly for the last
year or so.

This may be due to a bad switch (either failing or poorly designed),
or it may be that I have exceeded some specification for number of
switches in series (perhaps they get confused when stacked this deep).
Or it might be something else.  Ideas?

Keith

-- 
Keith Lofstrom          keithl at keithl.com         Voice (503)-520-1993
KLIC --- Keith Lofstrom Integrated Circuits --- "Your Ideas in Silicon"
Design Contracting in Bipolar and CMOS - Analog, Digital, and Scan ICs



More information about the PLUG mailing list