From: CRDGW2::CRDGW2::MRGATE::"SMTP::DECWRL.DEC.COM::SIMPACT!JEH" 19-SEP-1989 17:49 To: MRGATE::"ARISIA::EVERHART" Subj: changes to recommended trailblazer setups Message-Id: <8909190208.AA07005@decwrl.dec.com> Received: from decwrl.dec.com by DRYCAS.CLUB.CC.CMU.EDU; Tue, 19 Sep 89 17:18 EDT Received: by decwrl.dec.com; id AA07005; Mon, 18 Sep 89 19:08:45 -0700 Received: by simpact.com (DECUS UUCP w/Smail); Mon, 18 Sep 89 19:00:19 PDT Date: Mon, 18 Sep 89 19:00:19 PDT From: Jamie Hanrahan Subject: changes to recommended trailblazer setups To: vmsnet@DRYCAS.CLUB.CC.CMU.EDU Some recent experiments with the Telebit Trailblazer lead me to conclude that the setup instructions given in Appendix A of the DECUS uucp System Manager's Guide are non-optimal. First, under some combinations of long-distance access systems, local PBX's, etc., plus the fact that we have configured the modem to answer with the PEP-mode tones last, the default dial timeout of about 45 seconds is right on the hairy edge. I've changed my dial script and my modem setup to use 90 seconds instead, and calls to one neighbor (which formerly almost never went through) are now working fine. To change the dial script, add the line ctime 90000 somewhere -- anywhere before the "dial" command is fine. To change the modem, see the next section. Second: The tb has a built-in data compression feature. This can be a win in some applications, and in the modem setup instructions we provided, we enabled it. However, the bulk of the traffic we are trying to move is news, and news is ALREADY compressed via modified Lempel-Ziv. So there's no point in asking the modem to try compressing it further. Indeed, in a test I just ran, I sent a large compressed file to the same neihbor twice, once with the modem's compression enabled and once without. Throughput was around 1000 bytes/sec and 1300 bytes/sec, respectively. So, unless most of your trailblazer traffic is something other than news, you should probably disable compression. To change the modem setups, connect to the modem with a serial port (as directed in Appendix A), and after getting an "OK" from the modem, send it AT S7=90 S110=0 &W the spaces aren't necessary but don't hurt. S7=90 sets the wait-for-carrier time to 90 seconds, S110=0 disables compression, and &W writes the result to the EEPROM. A subsequent AT&N will display the EEPROM parameters, allowing you to confirm things. --- Jamie Hanrahan, Simpact Associates, San Diego CA Chair, VMSnet [DECUS uucp] and Internals Working Groups, DECUS VAX Systems SIG Internet: jeh@simpact.com, or if that fails, jeh@crash.cts.com Uucp: ...{crash,scubed,decwrl}!simpact!jeh