The Ethernet Datalink

Introduction

"Ethernet" is the term that is casually applied to a number of very different data link implementations.  You will hear people refer to "Ethernet" and they might be referring to the original DEC, Intel and Xerox implementation of Version 1 or Version 2 Ethernet.  This, in a sense, is the "true" definition of "Ethernet".  When the IEEE built the 802.3 standards in 1984 the term "Ethernet" was broadly applied to them as well.  Today we talk about "Fast Ethernet" and, although this technology bears many similarities to its predecessors, the engineering technology has changed dramatically.

Whatever you call it, this is a Data Link technology - responsible for delivering a frame of bits from one network interface to another - perhaps through a repeater, switch or bridge.

Please select one of the following links :

Frame Formats

The four ways that frames may be structured (contains 3D diagrams and analysis of frames).

Media Access

Taking turns accessing the cable using the rules of Carrier Sense Multiple Access with Collision Detection (CSMA/CD)

Collisions

The results of simultaneous transmissions on the media: Fragments, Runts, CRC Errors

Propagation Delay

The relationship between maximum cable length and minimum frame size is based on the propagation delay of the signal

Frame Corruption

Troubleshooting coaxial Ethernet networks by examining the types of corruption patterns that result from specific events

Interframe Gap

The 9.6 microsecond interframe gap and an understanding of its purpose

Signal Encoding

Manchester Encoding for the electrical Ethernet signal