grr@cbmvax.UUCP (George Robbins) (03/18/88)
This goes back to the dreaded S92=1 setting. If we agree that this
setting is needed to allow incomming calls from call-progress-detecting
modems like the USR Courier, two problems present themselves on calls
coming from remote trailblazer modems.
First is the problem with the calling modem having to explicitly
specify s50=x where x depends on the type of modem the trailblazer
is calling. I previously suggesting using the value S50=254 to
mean "use mode most appropriate for current interface rate". This
still seems reasonable to me. One person objected, claiming that
254 already had some special significance, however this was really
for S51 not S50.
The second problem is the length of time it takes the answering
modem to complete the answer tone / PEP training sequence when S92=1
is selected. By observation, this takes something like 45 seconds,
plus the time required from dialing to ring.
Most uucp versions have a hard-coded response timeout of 60 seconds,
which is kind of marginal it it takes a long time to complete the call.
Several distributed versions of unix have a shorter fuse timout of 45
seconds.
These people can have real problems calling into a Trailblazer with
S92=1, since the uucp program may time out before getting a "CONNECT"
even though the call is progressing normally.
It's not clear that such a prolonged "low-speed" answer tone and
delay before the PEP sequence is really needed. I seems like it
would be fairly simple to define other S92 values that would allow
an abbreviated low-speed segment that would work with most if not
all incoming low speed modems.
Other Issues:
What is the relationship of the UUCP spoofing and compression options?
Actually, what is a general outline of how the cmpression mode actually
operates?
What actually triggers entry and exit into UUCP spoofing mode? Does
the code support alternate packet sizes and/or interfere in the negotiation
as seems to be it's habit?
Are there any changes to the P/N 90035-01 Rev. A Users's manual other
than the undocumented S51=254 setting?
Any special USENET discounts on the rack mount varients? You know,
50% off if you buy a rack with at least 4 modem cards...
--
George Robbins - now working for, uucp: {uunet|ihnp4|rutgers}!cbmvax!grr
but no way officially representing arpa: cbmvax!grr@uunet.uu.net
Commodore, Engineering Department fone: 215-431-9255 (only by moonlite)