Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!brl-adm!brl-sem!ron From: ron@brl-sem.ARPA (Ron Natalie) Newsgroups: comp.dcom.lans Subject: Re: Tradeoff between LAN repeaters and routing gateways? Message-ID: <567@brl-sem.ARPA> Date: Wed, 7-Jan-87 21:07:48 EST Article-I.D.: brl-sem.567 Posted: Wed Jan 7 21:07:48 1987 Date-Received: Thu, 8-Jan-87 00:46:34 EST References: <476@savax.UUCP> Organization: Electronic Brain Research Lab Lines: 62 In article <476@savax.UUCP>, dove@savax.UUCP (webster dove) writes: > > We are just beginning to setup a TCP/IP network here. We have several > facilities separated by 5-20 miles, and most facilities have several > distinct ethernet cables. > > I am looking for explanations of the tradeoffs between using filtering > repeaters to convey traffic between wires and between facilities (e.g. > VITALINK) and using TCP routers for the same purpose (e.g. PROTEON). > First, your terminology is off. The VITALINK TRANSLAN is not a repeater. A repeater passes through the ethernet signal between two points. The translan actually receives the packet into it's memory and then retransmits it on the other cable. The community is not overly sure what to call this but the word "bridge" in lower case seems to be gaining popularity. The Proteon is not a TCP router, it is an IP router. BRIDGE: VitaLink TransLan, DEC LANBridge ADVANTAGES- - Will pass data without regard to protocol. - Maintains your ethernet address space so every host is direcly accessable to every other host. - Broadcast messages are received everywhere. DISADVANTAGES- - Problems on one ethernet cable such as transceiver jabbering will be propagated to other segments. - Broadcast messages are receieved everywhere. - All segments of the cable will receieve a large percentage of the total traffic, hence you will run into the maximum throughput limits faster. ROUTER: Proteon, CISCO, Bridge, among others ADVANTAGES: - Isolates the cable segments from each other for better performance and fault tolerance. - Multiple routes can be provided in the system to provide for increased performance and redundancy. - Can interface to things other than Ethernet. DISADVANTAGES: - Some level of IP routing must be done (generally handled automatically though). - Must be designed to handle each protocol that they will route (multi-protocol routers have been built, or just use a different router for each protocol). ================================== Frankly, the performance and fault tolerance problems are enough to scare anyone into routers. There is an ethernet spread through eight states by satellite and TRANSLAN boxes and while it is amusing, I'm sure that any of the parties can tell you it is no way to run a network. -Ron