Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!uunet!virtech!cpcahil
From: cpcahil@virtech.uucp (Conor P. Cahill)
Newsgroups: comp.unix.i386
Subject: Re: ISC 2.2 SL/IP throughput?
Message-ID: <1990Aug29.112550.563@virtech.uucp>
Date: 29 Aug 90 11:25:50 GMT
References: <25@astph.UUCP> <3694@wb3ffv.ampr.org> <26@astph.UUCP> <1990Aug23.160013.1199@scuzzy.mbx.sub.org>
Reply-To: cpcahil@virtech.UUCP (Conor P. Cahill)
Organization: Virtual Technologies Inc., Sterling VA
Lines: 28

In article <1990Aug23.160013.1199@scuzzy.mbx.sub.org> src@scuzzy.mbx.sub.org (Heiko Blume) writes:
>
>can someone tell me what throughput i can expect with sl/ip over
>a modem connection with HST modems (14400bps)? we talk to the modems
>at 19200 and use hardware flow control (FAS with 16550 chips). we did
>a ftp and the throughput was ~0.2 KB/s on a 600KB file, which is unacceptable.
>did we do something wrong? (of course we did sldialup/attach 19200 ttyF01).

Your problem is probably caused by the fact that the HST modems running at 
14.4kbs are not truely full duplex.  They (in a similar vain to the t2500) have
a high speed channel in one direction and a low speed reverse channel 
(switching the directions as necessary).  

This is a really bad scenario for packetized protocols that require
acknowledgment packets (unless the modem "spoofs" the protocol, like what
the Telebits do to UUCP).

Your best bet would be to get a v.32 modem (if you require the HST 14.4 
compatibility for other purposes, use an HST dual-standard).

Full duplex 9600 baud modems (i.e. v.32) should get around 800 bytes/sec
throughput on clear lines.


-- 
Conor P. Cahill            (703)430-9247        Virtual Technologies, Inc.,
uunet!virtech!cpcahil                           46030 Manekin Plaza, Suite 160
                                                Sterling, VA 22170