pjg@unrvax.UUCP (Paul Graham) (08/02/85)
[] I've been following the discussion (or former discussion) of Enet on broadband networks but, unless I missed something, it seems nobody has a definite answer. We'd like to run our (as yet uninstalled) Enet on our installed broadband (Sytek). Ideally we'd like an Enet to broadband (Etherband) transceiver that costs about what an ordinary Enet transceiver does. Failing that we'd like a nice, moderate cost, high speed gateway box that will (mostly) transparently handle remote addresses. I've spoken with VitaLink and a $25k box (after you buy full-duplex channel capability, I think) that gives me four 56Kbaud lines is not what I'm looking for. The Bridge GS6 (i think) inter-net box is both cheaper and faster (I'm confused by this since the salepeople make them sound equivalent) but if we could we'd like to get to at least 6Mbits (since that's how big our broadband channels are) and wouldn't mind 10 unless of course cost increases exponentially with speed. Sorry if I missed the answer to this already, but if you have some data/pointers/good advice please send me some mail. Naturally if I'm flooded with inquiries and receive some good stuff I'll summarize here. -- Thanks for your time. Paul Graham 702/784-6007 ucbvax!decvax!seismo!unr70!unrvax!pjg unr70!unvax!pjg@seismo.CSS.GOV
hedrick@topaz.ARPA (Chuck Hedrick) (08/03/85)
A number of questions recently have to do with connecting LAN's in different locations to each other. We have been looking into this ourselves, so let me share what we have seen so far. I'm sure there are more products out there, so we'd like to hear from others who have been looking. (In particular, I have omitted Ungermann-Bass because I don't happen to know what they are doing at the moment.) If distances aren't too long, the simplest approach is to have two Ethernets meet at an Ethernet/Ethernet gateway. With the fiber remote repeater, this technique can be used with buildings up to 1 km apart. Bridge Communications. They have something that will connect two (NB: only 2) adjacent Ethernets running XNS. It is rated at 370 packets per sec or 1 Mbit, whichever is lower. We expect to see a TCP version of this within 6 mo or so. Proteon. They are offering an LSI-11 based gateway. This is probably going to handle 200 packets per sec or so. This leaves many people feeling a bit unsatisfied, though there seems to be reasonable evidence that no one actually needs more speed than this in practice. This gateway supports Ethernet, Arpanet (BBN 1822), and Proteon's own token ring network, and possibly other things as well. Sometime this fall they will have a 68000-based gateway that is similar, but has a higher throughput. These gateways handle TCP/IP and CHAOS. I'm not sure what else (but I know that it does not handle DECnet). Proteon's networks appear to be commerical versions of MIT's technology. I suspect that it is possible to get the code directly from MIT if you do not want commerical support. Stanford gateway. Stanford has been using 68000-based gateways for some time. It appears to be possible for Universities, at least, to get information on how to build one of these. They can handle up to 5 network interfaces per gateway. They use off the shelf boards, with software and a ROM from Stanford. Unfortunately, the Ethernet interface is a 3Com multibus board, which is no longer made. They claim up to 500 packets per second. It supports TCP/IP, PUP, and XNS. They also have a method for handling twisted pair at 1.5Mbits, though it involves modifying some hardware. For longer distances, there are several solutions, including conventional phone lines (9600 to 56Kb) and T1. Bridge: They have XNS support for lines up to 56Kb. I do not recall the status of their T1 support, but I know something is either planned or done. These products will all be appearing for TCP/IP within the next months. Vitalink: I don't much about this, but it supports at least phone lines, and possibly also other media. It uses Bridge hardware and some DEC algorithms. It is protocol- independent. Broadband. These are gateways between Ethernet and an Ethernet-like channel running on Broadband. You would use the broad-band as a "backbone", connecting your buildings. Individual machines would normally be connected to an Ethernet. The Ethernet in each building is then gatewayed to the broadband. Bridge: They have a broadband product that puts something like 2 Mbits (maybe 1 or 1.5) on one 6-Mbit broadband channel, with gateways between this and Ethernet. I believe the gateways understand XNS, and they are about to have TCP/IP versions. Applitek: They have a broadband product that puts 10 Mbits on a 6 MHz channel. It is protocol-independent. Although some people have said that it is in production, it appears to be in final debugging and testing now. Tools for system administration are still being implemented. Although you can have several broadband channels on one cable, there is no coordination among them. (I.e. depending upon your configuration, you may end up will all of your packets going on both channels.) Although it seems like it will be a few months before all of the problems are worked out, many people like this product because it makes the best use of the bandwidth of the broadband cable. Bridge uses the same channel, but gets much less throughput on it. DEC uses 3 channels to get the same throughput. DEC: They have something that works just like an Ethernet, but runs on broadband cable. This means that you don't have to use it as a gateway. You can connect hosts to it directly. The interface looks just like an Ethernet transceiver, so existing Ethernet host implementions will normally work with it. Of course if you have lots of hosts at a given site, you may want to put them on an Ethernet and then use an Ethernet to Ethernet gateway to connect that Ethernet to the broadband. Note however that they take three 6 MHz broadband channels to get 10Mbits of throughput. And currently only one particular set of channels is supported. 3M: We know of this only indirectly. Apparently it is a few Mbits on a single 6MHz channel, and has gateways to Ethernet using TCP/IP. I don't think it is actually in production use yet. Fiber. This is similar to the broadband networks, but uses optical fiber. Fibercom. They have something that work like an Ethernet, with the same 10Mbit bandwidth. But it uses fiber instead of Ethernet cable. You would use it like the DEC broadband Ethernet. I.e. you could hook machines to it directly, or hook your machines to an Ethernet and use an Ethernet to Ethernet gateway between the Ethernet and the fiber. Proprietary networks. These are networks that normally work over more than one medium. Proteon. They have two networks, one around the same speed as Ethernet and another something like 60Mbits. They use token ring technology, and run on twinax or optical fiber. They do not have interfaces which are compatible with Ethernet. However there are Proteon interfaces for a great variety of machines, and most of the major buses. As long as your machine has a device driver, it would be used much like Ethernet. Like Ethernet, you can run several protocols (TCP/IP, DECnet, CHAOS, etc.) on it at the same time. You could also connect your machines to Ethernet and use gateways between Ethernet and Pronet. Proteon will supply these gateways.