Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!rutgers!netsys!faatcrl!jimb From: jimb@faatcrl.UUCP (Jim Burwell) Newsgroups: comp.mail.uucp Subject: Re: New UUCP Protocol (was: Re: Zmodem added to UUCP) Message-ID: <1035@faatcrl.UUCP> Date: 10 Oct 89 01:12:07 GMT References: <1024@faatcrl.UUCP> <710@lakart.UUCP> <1029@faatcrl.UUCP> <688.252e37c2@simpact.com> <1032@faatcrl.UUCP> <25@van-bc.UUCP> Organization: FAA Technical Center, Atlantic City NJ Lines: 73 sl@van-bc.UUCP (Stuart Lynne) writes: >In article <1032@faatcrl.UUCP> jimb@faatcrl.UUCP (Jim Burwell) writes: >> >>jeh@simpact.com writes: >Perhaps if you're talking to your PEP modem at 9600 bps. But not if you are >using 19.2. At that speed uucp with it's overhead should be able to supply >enough data to completely fill the bandwidth available for data between the >two modems (something like 14kbps before compression). Yep. I know that.. We are running 19.2. But your point is taken. The modem's buffer is full before it can even send it over the PEP link. So as long as no PEP bandwidth is used up by the modems processor negotiating 'g' with the computer, no throughput is lost. However, throughput IS still lost using any other modem than a Telebit at 19.2 Kbps, with 'g' spoofing enabled. There are still a lot of plain 2400 baud modems out there which could be gettting better throughput using a better protocol. Not to mention, a lot of buffered, MNP modems which don't do spoofing! I'd HATE to run UUCP on a USR HST Dual-Standard with MNP! Even though it's most likely a faster modem than Telebit's current PEP modems, 'g' would kill it, unless USR put 'g' spoofing into that one. (BTW, does anyone know which modem is faster? The Telebit T2500, or the USR HST Dual-Standard.. My friends stated Zmodem CPS times of 1600 and up lead me to believe that the DS is faster.. I heard you can only get 1600-1800 on a TB on a "good day" :-) >Remember that what two PEP's do to spoof uucp is to talk "g" packet protocol >between the modem and the computer. But simply assume an error free link >between themselves. Yep. I know this. But does the Telebit have a dedicated processor to do this ? Does the 'g' negotiation and PEP transfer occur asynchronousely ? >Unless they spoof Zmodem you will probably see a slight drop in throughput >as the modem now has to transfer the Zmodem framing as data. They didn't >have to transfer the uucp framing char's. Another good point. I think Zmodem sends 32 bytes of framing data per packet... Am I wrong ? That would give 'g' spoofing an advantage over Zm with that specific modem... [unix stuff deleted] >This means that if the receiving uucico has been swapped to disk and there's >no one there to pull the data out you won't get an overrun. Everything just >sits there until uucico swap's back in and acks the received packets. If you >run a window size greater than 3 or increase the packet size the tty driver >will overrun it's CLIST buffers and dump everything. Then we usually will >see a 10 second wait until the sender resends. Yike.. ! That sounds like a Unix problem to me though. I wonder if you can code uucico to forbid the OS from swapping uucico (or buffers, or whatever a CLIST is :-) ? That's scary! I hope Unix doesn't swap device drivers too! :-). I can see it swapping the program doing the high level protocol, but not the drivers ! Is there anyway to force it not to swap your poor program ? Bye Jim -- +------------------------------------------------+--------------------------+ | James S. Burwell | | | | "UseNet...A text network | | UUCP: | in a binary world" - Me | | ...!{ames!netsys|rutgers}!faatcrl | | | !jimb | "How do you say | | . | 'multitasking' in | | Internet: . | MS-DOSish? Network | | // jimb@faatcrl.UUCP . ** | File Server!" - Me | | // . **** | | | \\ // GEnie: Airwarior: . .** | | | \X/ JIMBURWELL Techrat . | | +------------------------------------------------+--------------------------+