hw5 - duplex transmission, which supports multiple...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
Zhou, HuanXian HW5 ID: 0225418 EE136 Instructors: Kang Xi 1. A disadvantage of the CSMA/CD is the capacity wasted due to contention. Suppose that time is divided into discrete slots, with each of N stations attempting to transmit with probability p during each slot. What fractions of slots are wasted due to multiple simultaneous transmission attempts? The fraction of slots wasted due to multiple transmission attempts is equal to the probability of 2 or more transmission attempts in a slot Pr[2 or more attempts] = 1 – Pr[no attempts] – Pr[1 attempt] = 1 – (1 – p) N – Np(1 – p) N–1 2. In today's typical Ethernet, the stations are connected to an Ethernet switch using twisted pairs. In this case, do we still need CSMA/CD to control the medium access? Explain why. No, because the Ethernet switch uses the switching technology, it is a fully
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: duplex transmission, which supports multiple simultaneous transmissions; therefore, there is no need of CSMA/CD. 3. Station A, B and C are interconnected through an Ethernet switch. At a certain moment, A and B start sending packets to C simultaneously. Do you think this will cause a transmission collision at station C? Do we need CSMA/CD to handle this? If not, what is the solution? It would not cause a transmission collision at station C, because a switch supports multiple transmissions. Therefore we dont need CSMA/CD to handle it. The following is the solution for this transmission: Switches have internal memory to buffer incoming packets, When two or more packets contend for the same destination output, only one packet is delivered at a time, other packets are delayed in the memory....
View Full Document

This note was uploaded on 11/02/2010 for the course EE 136 taught by Professor Kang xi during the Spring '10 term at NYU Poly.

Ask a homework question - tutors are online