In telecommunication, token passing is a channel access method where a signal called a token is passed between nodes that authorizes the node to communicate. The most well-known examples are token ring and ARCNET.
Token passing schemes provide round-robin scheduling, and if the packets are equally sized, the scheduling is max-min fair. The advantage over contention based channel access is that collisions are eliminated, and that the channel bandwidth can be fully utilized without idle time when demand is heavy. The disadvantage is that even when demand is light, a station wishing to transmit must wait for the token, increasing latency.
Some types of token passing schemes do not need to explicitly send a token between systems because the process of "passing the token" is implicit. An example is the channel access method used during "Contention Free Time Slots" in the ITU-T G.hn standard for high-speed local area networking using existing home wires (power lines, phone lines and coaxial cable).
Famous quotes containing the words token and/or passing:
““With the gracious consent of the audience, you will be made to don the red tophat”Ma token phrase that the courts had evolved, whose true meaning was known to every schoolboy.”
—Vladimir Nabokov (1899–1977)
“It’s a particular Observation I have always made, That of all Mortals, a Critick is the silliest; for by inuring himself to examine all Things, whether they are of Consequence or not, he never looks upon any Thing but with a Design of passing Sentence upon it; by which Means, he is never a Companion, but always a Censor.”
—Richard Steele (1672–1729)