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Alime.232 net.lan utzoo!decvax!harpo!floyd!vax135!lime!martin Fri Apr 23 09:26:58 1982 Comments on CSMA vs token passing

From: lime!houxe!houxi!ihnss!mhtsa!mhuxt!eagle!karn

typical coaxial cable is .67c, not .3c, although it can be higher with different impedances and dielectrics.

Token passing has MORE problems in long-propagation-time environments, not fewer. Just passing the token around the network can waste a lot of time if there are many nodes in the network.

I don't think anyone can argue that one protocol is inherently better than others; most have their strengths and weaknesses. CSMA works better when there are a large number of nodes, each with relatively little traffic (e.g., terminals); token passing works better when the traffic builds up (e.g., computer-to-computer file transfers).

For internal BTL applications, however, you almost have to admit that ANYTHING is better than the absurd practice of using 212 modems and voice PBXs for data communications. This makes about as much sense as IBM trying to switch voice with one of their front-end terminal processors. Its getting to the point where I don't CARE what is used to replace the Dimensions; I'd just like to see it soon!

Phil Karn MH 3C-339 x6646

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