Note: 

In early Ethernet, there were no Network Bridges

• Connected computers within limited distances. 
• Originated at Xerox PARC
• All computer connected by a single cable (like cable TV)
• All information available to all computers
• Message contains address of sender and recipient computers
• Correct computer picks up the message
• How do you share the cable to send?
• 3COM developed Network cards for PC machines.
• After Novell Netware, one computer could host files available to others, also printers

Sending a message from A to D:

A checks if line is busy,

A sends message to D but everyone can see the message

D sees a message passing by and grabs it.

After Cisco routers, a message to an outside computer would be allowed to go outside this network.

Typical speeds:

• 2Mb/s - early systems
• 10Mb/s - still in use
• 100Mb/s - most used today
• 1000Mb/s or 1Gb/s - recently available