Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!tut.cis.ohio-state.edu!usenet.ins.cwru.edu!cwjcc!neoucom!wtm From: wtm@neoucom.UUCP (Bill Mayhew) Newsgroups: comp.dcom.modems Subject: Re: should i expect MNP4 to be faster than non-MNP? Summary: What about MNP packet size? Message-ID: <1876@neoucom.UUCP> Date: 17 Jan 90 12:09:01 GMT References: Distribution: comp Organization: Northeastern Ohio Universities College of Medicine Lines: 33 I use an AT&T CEO 2224 MNP modem (level 4) in my office to tallk to a Trailblazer Plus on our vax and a TB Plus on my 3B1 at home. It has been discussed here that the TB Plus 4.0 firmware is not fully MNP 4 compliant, so this could affect my results. I have noticed that when I cat a file to the screen of the terminal in my office that characters arrive at what seems to be a normal 2400 baud rate, followed by about a 1 second pause, then a steady issue of characters follows at 2400 baud or perhaps slightly faster. The effect is not limited to the CEO 2224 modem. I also see the pause behavior when using the software based MNP that is available for use with Softklone's Mirror III package that I use on my protable computer. There are no explanations of MNP levels, etc in the Trailblazer or the Softklone manuals and only a few small teases in the AT&T manual. One of the things that can be set in the AT&T manual is an S register to select MNP packet size, though in pactice setting different size packets hasn't been either beneficial or damaging for me; the pause always seems to be the same, and seemingly is not some soft of flow control mechanism -- it only happens once at the beginning of catting a file. I don't see the behavior when I disable MNP, so the pause is some sort of MNP artifact. In both cases, the trailblazer is talking to the host at 19200 with flow control on that end, and the CEO 2224 is talking to the terminal at 4800. On the portable, the only choice of modem interface is 2400 due to a limitation of the modem. Bill