Lecture 14: Multiaccess Networks

Ethernet/802.3

Ethernet (also known as IEEE 802.3 and ISO 88023) is the dominant LAN technology at present. Ethernet defines a Medium Access Control (MAC) technology for operation over various types of cabling in a bus architecture.

Until recently^[1], the predominant form of Ethernet used so-called thin wire coaxial^[2] cabling. A typical installation might have looked like:

Whilst this is no longer the most common hardware used for Ethernet/802.3, it exemplifies the shared medium idea that it is based on. Note the use of "T-connectors" on each computer, and the "Terminators" at each end of the network.

^[1] OK it's not so recent. Basically this cabling technology was no longer being installed by about the mid-1990s.
^[2] Historical note: this was also called "cheapernet" or "10Base2". Exercise: cheaper than what?

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