How does the token passing work on a token bus?

Answer 1

This answer assumes you are asking about a token ring network. I don't know about any other 'token bus topology'. You can think of this as a group of people (say 10 people) standing in a circle. An (one) envelope is being passed from one person to the next. There is not a "From" or "To" address on the envelope. So it comes in on the left hand (received) and is passed out by the right hand to the next (transmitted) person, ad infinitum. A token ring is a serial topology - a message has to passed from one station to the next. The message is seen at a station. and if the addressing in the message block matches it's addrress, the information within the message is removed and retained by that station, and the rest of the package (token) is transmitted on to the next station. Of course there is no info in there for this next station, so it just re-transmits on, and this package is passed around, and around, and around. If a station has someting to transmit out, i.e. a browser request or a file request to a network drive, etc, it waits until the empty token get around to it, captures the token to put in the addressing and message blocks, then transmits. The appropriate gateway will capture it for a browser request, or a server will intercept it for a file request. Again - notice this is a serial topology, one station after the next. But it is quick - either 4 or 16 Mbps. Since it is serial, there should never be a colision, and it should be very reliable, very fast. Unfortunately, the connectors for the cables at the wall stand out pretty proud, and are prone to getting bumped, knocked, kicked out of the wall connection. They are designed to not break the ring if this happens, but of course, that station is off line (same as removing the enet cable connector from the wall).

Answer 2

The data is bounced from one end of the bus line to the other and back instead of following a loop continuously. ^_^ JunkCollector ^_^