Token rings Token rings were developed by IBM in early 1980s Token: a bit sequence Token circulates around the ring Busy token: 01111111 Free token :01111110 Token Ring When a node wants to transmit Wait for free token Remove token from ring(replace with busy token) Transmit message When done transmitting, replace free token on ring Nodes must buffer 1 bit of data so that a free token can be changed to a busy token Token ring is basically a polling system Token does the polling Slide 10Token rings • Token rings were developed by IBM in early 1980’s • Token: a bit sequence – Token circulates around the ring Busy token: 01111111 Free token: 01111110 • When a node wants to transmit – Wait for free token – Remove token from ring (replace with busy token) – Transmit message – When done transmitting, replace free token on ring – Nodes must buffer 1 bit of data so that a free token can be changed to a busy token • Token ring is basically a polling system Token does the polling Token Ring Eytan Modiano Slide 10