B227 Lecture Overheads - Topic 4: Introduction

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The Medium Access Sublayer

Topic Outline:

The Channel Allocation Problem

Multiple Access Protocols

IEEE Standard 802 for LANs

Bridges

High Speed LANs

Satellite Networks

The medium access sublayer is also called the Medium Access Control (MAC) sublayer. It is especially important in LANs, which is why we discuss it extensively in this topic.

Broadcast vs Point-to-Point Networks

In previous topic, we assume point-to-point networks

We discussed how to set-up a reliable and efficient communication between two adjacent machines. This means it must be going from one machine to one other machine (ie. point-to-point).

DLL should also cater for reliable and efficient transmissions in a broadcast network.

Note that in a broadcast network, we can still only have one sender and one receiver. It's just that we stop worrying about addressing to the particular receiver, and just send the frames to everyone. The DLL on the proper receiver will accept it. The rest will discard the frame.

Since these services forms such a major part of the DLL, we put them into a sublayer by itself.

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