Inte
1-58705-001-3
C H A P T E R 7
Chapter Goals
• Understand the required and optional MAC frame formats, their purposes, and their compatibility
requirements.
• List the various Ethernet physical layers, signaling procedures, and link media
requirements/limitations.
• Describe the trade-offs associated with implementing or upgrading Ethernet LANs—choosing data
rates, operational modes, and network equipment.
Ethernet Technologies
Background
The term Ethernet refers to the family of local-area network (LAN) products covered by the IEEE 802.3
standard that defines what is commonly known as the CSMA/CD protocol. Three data rates are currently
defined for operation over optical fiber and twisted-pair cables:
• 10 Mbps—10Base-T Ethernet
• 100 Mbps—Fast Ethernet
• 1000 Mbps—Gigabit Ethernet
10-Gigabit Ethernet is under development and will likely be published as the IEEE 802.3ae supplement
to the IEEE 802.3 base standard in late 2001 or early 2002.
Other technologies and protocols have been touted as likely replacements, but the market has spoken.
Ethernet has survived as the major LAN technology (it is currently used for approximately 85 percent of
the world’s LAN-connected PCs and workstations) because its protocol has the following
characteristics:
•
Is easy to understand, implement, manage, and maintain
• Allows low-cost network implementations
• Provides extensive topological flexibility for network installation
• Guarantees successful interconnection and operation of standards-compliant products, regardless of
manufacturer
7-1
rnetworking Technologies Handbook
Chapter 7
Ethernet Technologies
Ethernet—A Brief History
Ethernet—A Brief History
The original Ethernet was developed as an experimental coaxial cable network in the 1970s by Xerox
Corporation to operate with a data rate of 3 Mbps using a carrier sense multiple access collision detect
(CSMA/CD) protocol for LANs with sporadic but occasionally heavy traffic requirements. Success with
that project attracted early attention and led to th