Backoff Protocols WHEN TWO (OR MORE) STATIONS NOTICE A COLLISION, THEY HAVE TO BE "POLITE" ABOUT TRYING AGAIN IN A CAREFULLY PLANNED WAY. IF THEY ALL TRY AGAIN AS SOON AS THEY SENSE SILENCE, THEY MAY ALL COLLIDE AGAIN. IF THEY ALL WAIT SOME FIXED TIME BEFORE TRYING AGAIN, THEY WILL STILL COLLIDE AND WASTE EVEN MORE TIME. AS A RESULT, AFTER A COLLISION, EACH STATION MUST RANDOMLY DECIDE HOW LONG TO WAIT BEFORE TRYING AGAIN.

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This page is part of a section of lecture slides related to " Broadcast Networks " within the topic "Multi-machine Networks". Other slides within this section and other sections of slides for the topic "Multi-machine Networks" can be accessed using the links below. Too Many Wires DIRECT CONNECTIONS Switching Techniques The Telephone Network The Telephone Network (cont.) Circuit Switching A Path through the Phone System Phone System Data Services Message Switching Message Switching (cont.) PACKET SWITCHING Comparing Switching Techniques Comparing Switching Techniques (cont.) THE NEED FOR "PROTOCOLS" Broadcast Networks Broadcast Networks "Bus" Networks "Bus" Networks (cont.) A More Familiar "Bus" Network CSMA/CD = Ethernet + Appletalk Collision Detection Backoff Protocols Ethernet Advantages Ring Networks Ring Networks = Simplified Switching Token Rings Token Passing Advantages and Disadvantages of Rings