RANCK@VTVM1.BITNET.UUCP (03/02/87)
As Geoff points out there may be no way to tell when your modem is doing error correction, although some have lights that indicate error correction activity. Then there is the question of error correction at the various levels in the process. If your software does error correction and your modem does error correction and the network does error correction, each layer adding a few more bytes, you end up with more bytes of error detection/correction than data, and of course more bytes means more chance of error. In some cases, though I can't think of any, the error correcting protocols might interfere with each other. I suppose the answer is to maintain a high degree of cynicism because the world is imperfect and error correcting protocols are too. Bill Ranck
dpz@paul.UUCP (03/09/87)
> From: RANCK@VTVM1.BITNET ("Wm. L. Ranck") > As Geoff points out there may be no way to tell when your > modem is doing error correction, although some have lights that indicate > error correction activity. Activity... argh - my Racal-Vadic 2400PA's idea of activity is flashing a light when it is exchanging error correction code, not when it is actually correcting errors. Big help - to me that is just as good as having a light on all of the time signalling enabled error correction, and if you have this modem rack mounted, it is all but ignored in daily use. To have it flash when a correction actually takes place would be more helpful, but then again, staring at my modem, waiting for it to flash a correction, isn't very high on ways that I like to spend my time. Some kind of internal log of actual error correction inside of the modem would be nice. This way you could check after a file transfer what happened inside that little black box. What might even be better is for the modem level xfer protocol (terminal/file xfer program in the case of a micro) to get together with the modem and relay error messages up higher. Ad {nauseam, infinitum}. > Then there is the question of error correction at the various levels > in the process. If your software does error correction and your modem > does error correction and the network does error correction, each layer > adding a few more bytes, you end up with more bytes of error > detection/correction than data, and of course more bytes means more chance > of error. In some cases, though I can't think of any, the error correcting > protocols might interfere with each other. Strength (stench?) in numbers! :-) This is, of course, a trade-off that we make for ensuring the 'rightness' of our data. The problem with all of this is that each is independant, so you can use an error correcting modem without an error correcting network (OK, without a network, period), and you can use an error correcting network with a non-error-correcting modem. *sigh* What I need is a nice toggle switch to turn the correcting on or off for each layer, and leave it on only for those layers that actually provide the 'best' correction algorithms. dpz -- David P. Zimmerman "When I'm having fun, the world doesn't exist." Arpa: dpz@rutgers.edu Uucp: ...{harvard | seismo | pyramid}!rutgers!dpz