[comp.dcom.lans] "dead ports" on a Bridge LS/1 terminal server

curt@dtix.ARPA (Curt Welch) (07/29/89)

For several months, we have been using a Bridge LS/1 (CS/1) 64 port
TCP/IP terminal server to connect a bank of 48 Bell 212 modems to our
local ethernet.  We have been seeing a recurring problem with "dead"
ports and I would like to know if anybody else has seen this problem,
or if they have tried to use a Bridge LS/1 with dial-in modems.

What we have found, is that every few weeks, a bank of consecutive
ports on the LS/1 will stop working for no apparent reason.  When we
reboot the LS/1, the problem goes away, but nothing else we have tried
seems to clear the condition.

Typically, when a port goes "dead", the terminal server holds DTR high,
so the modem will answer the phone, but the terminal server never
responds with its welcome message and does not echo characters.

I've never seen more than 8 (or less than 4) ports go bad at once, and
the last bad port in the group has always ended on a multiple of 8.  For
example, twice now, we have seen ports 2 through 7 (the first port on
the server is 0) go bad.

Thanks for any help you can give us.

Curt Welch
curt@dtix.arpa
David Taylor Research Center, Bethesda, MD
(202) 227-1428