Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!husc6!cmcl2!phri!roy From: roy@phri.UUCP (Roy Smith) Newsgroups: comp.protocols.appletalk,comp.protocols.tcp-ip Subject: Using Kinetics boxes an an etherbridge Message-ID: <3057@phri.UUCP> Date: Sun, 6-Dec-87 22:50:13 EST Article-I.D.: phri.3057 Posted: Sun Dec 6 22:50:13 1987 Date-Received: Sat, 12-Dec-87 04:27:00 EST Organization: Public Health Research Institute, NYC, NY Lines: 84 Xref: mnetor comp.protocols.appletalk:294 comp.protocols.tcp-ip:1925 A couple of weeks ago, I asked what people thought about my idea of rolling my own bargain-basement etherbridge by putting two Kinetics KFPS-2's back-to-back on opposite ends of a LADC (4-wire leased) circuit, with Farallon PhoneNet drivers. Thanks to the following people for responding: husc6!sob (Scott Bradner) ucscc.UCSC.EDU!haynes (Jim Haynes) bu-it.bu.edu!ccjap (John Papadopoulos) bu-cs!bu-it.bu.edu!kwe (???) reed!goetz (Norman Goetz) I said that the PhoneNet could drive up to 4000 feet of twisted-pair cable, and that I hoped that our 2000-foot line-of-sight circuit would be withing that limit as-the-cable-snakes. Several people pointed out that phone lines run radially from the CO, with an LADC circuit consisting of two pairs (one from here to the CO, the other from there to the CO) patched together, and thus my 4000-foot hope was unrealistic. Perhaps, but I suspect that the people who suggested that have never been to Manhattan. CO's are every few blocks around here. I'm still hoping I'll make the 4000-foot limit, but I'm not holding my breath. Anyway, with much random editing, some of the more interesting comments. ---------------- From: allegra!likewise!uunet!ucscc.UCSC.EDU!haynes (Jim Haynes) Well, a guy here has been trying it for months and it still hasn't worked. I guess he doesn't have 'appropriate software' to download. The problem, as I understand it, is that the Kinetics software isn't prepared to cope with having two Kinetics boxes on the same Appletalk line. ---------------- From: cmcl2!harvard!husc6!bu-cs!bu-it.bu.edu!kwe It's crazy enough that it just might work! It's a novel idea. I like your inventiveness. I'm not sure you want to risk the investment on the Kboxes, since I would guess that the Appletalk link will not work. If you have the need for the Kboxes anyway, I would recommend trying the set-up you suggest. You can run anything you want on a LADC, but the telco will only guarantee (and it's a weak guarantee) service up to 9600 baud. 19.2k is usually worth a try, 38k is very iffy, and 56k is not going to cut it. 230k is way out there. You can get a good idea of how long your circuit is by knowing where your Central Office is physically located. If it's two miles away, you have a four mile LADC (20k ft). All local circuits originate in a CO, that's the definition of a CO. There is no patching on the pole. Chances are slim you will get a 4k ft circuit. But I like the idea anyway. ---------------- From: cmcl2!rutgers!mimsy.umd.edu!uunet!tektronix!reed!goetz (Norman Goetz) I think the Farralon hardware would work fine this way. [...] Unfortunately I don't think this will work. The hardware connections are fine but the Kinetics boxes are neither routers nor half-repeaters which is the role you are asking them to play. I've heard it described that the K-boxes are not true IP gateways but more remote front ends for devices on AppleTalk. Have you looked into twisted-pair Ethernet as a link? ---------------- In addition, I had a conversation with Bill Russell (russell@nyu.edu) who pointed out that even if the LADC could support AppleTalk over whatever length the circuit turns out to be, and if the boxes could be taught to be proper level-2 IP bridges, there is the problem of speed. We were talking about Ungermann-Bass etherbridges, which would cost about $16k for a pair, running 56 kbps over the LADC. Why so much, I asked, when it's obvious you can put together a reasonable stab at the same end result for about a quarter the price, and at five times the serial line speed? Bill's answer was that the limiting factor was not line speed, but CPU cycles. The U-B bridge can pass hundreds of packets per second. A kbox, with a poor little 6809 (?) processor in it, couldn't hope to keep up with a fraction of that traffic, not to mention the minimal amount of ram available (i.e. minimal routing tables, minimal packet buffering, etc). -- Roy Smith, {allegra,cmcl2,philabs}!phri!roy System Administrator, Public Health Research Institute 455 First Avenue, New York, NY 10016