[comp.dcom.modems] Dropouts using Telebit TB+'s when going through a 3rd modem?

earle@mahendo.Jpl.Nasa.Gov (Greg Earle) (08/25/88)

Here's a puzzler.  Given 3 machines, with the following modem links:

	A		B		C
	=		=		=
			TB+  < ------ > TB+
	NEC 2400 < -- > USR Courier 2400
	 "   ""  < ------------------ > USR Courier 2400  (same as B)

If I am logged on to B or C directly, and use tip(1) over the TB+'s to
the other, everything works fine, more or less (modulo the bursty-ness).
The TB+'s both have Rev. 4.0 PROMs, and I'm pretty sure they're set up
for no XON/XOFF flow control (mainly used for inter-office UUCP).

If I am logged on to B or C from A, using tip(1) over the normal 2400 baud
link, everything works fine.  No problems whatsoever.

However, if I tip from A to either B or C, then tip again over the TB+ to
C (or B), thus making a 2-hop connection, I will see dropped output, e.g.
when doing `ps -aux' or `cat /etc/termcap'.  I'd like to attribute it
to some sort of hardware setup mismatching, but I'll be damned if I can
think what it could be.  Especially when A <-> B works and B <-> C works,
but A <-> B <-> C doesn't.

Any ideas?

Sign me perplexed,
-- 
	Greg Earle		earle@Sun.COM
	Sun Microsystems	poseur!earle@mahendo.JPL.NASA.GOV
	Los Angeles Consulting	earle%mahendo@elroy.JPL.NASA.GOV
...!{cit-vax,ames}!elroy!poseur!earle	...!sun!tsunami!valley!poseur!earle