Explanation : The probability of success (i.e. exactly one frame in a slot) = 1 / e ~ 0.368. Then probability of a failure (no frames or multiple frames) = 0.632. Thus joint probabilities of the two uplink channels are : success on 1 and success on 2 : 0.135 (2 frames sent) success on 1 and failure on 2 : 0.233 (1 frame sent) failure on 1 and success on 2 : 0.233 (1 frame sent) failure on 1 and success on 2 : 0.399 (0 frames sent) Then expected number of success per slot. E = 0.35 * x + 0.233 * 1 + 0.233 * 1 + 0.399 * 0 = 0.270 + 0.233 + 0.233 = 0.736
Explanation : A bridge operates at the data link layer, giving it access to the physical address of all stations connected to it. Answer is physical addresses.