CSE 123 Lecture Notes - Lecture 25: Ieee 802.3, Master Sergeant, Ieee 802.11
3 Dec 2018
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Even w/ csma there can still be collisions! Requires a minimum frame size ( acquiring the medium ) Ensures sender sticks around and listens long enough to know whether frame succeeded! If it sees a collision, it should let everyone know about it. B must continue sending jam until a detects collision! A high energy signal that is sent to everyone. Wireless is typically half duplex; need an alternative! Worst case: a sends a msg at time t and b sends a msg at t + d - epsilon (just before receiving a"s msg) B knows there is a collision, but not a . a must keep transmitting until it can tell if a collision occurred! B must keep jamming 2*d so a knows there is a collision! Ieee 802. 3 ethernet specifics max value of 2d to be 51. 2 us. Relates to max dist. of 2500m between hosts.
