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Gigabit Ethernet (also know as Fast Ethernet
or Fast LAN) is Ethernet that provides speeds of 1000 Mbps—one billion
bits per second. It uses the same Ethernet frame format and media
access control technology as all other 802.3 Ethernet technologies. It
also uses the same 802.3 full-duplex Ethernet technology and 802.3 flow
control.
Like its Ethernet and Fast Ethernet
precursors, Gigabit Ethernet is a physical (PHY) and media access
control (MAC) layer technology, specifying the Layer 2 data link layer
of the OSI protocol model. It complements upper-layer protocols TCP and
IP, which specify the Layer 4 transport and Layer 3 network portions
and enable reliable communication services between applications.
These are some reasons to deploy Gigabit
Ethernet for greater bandwidth at the backbone:
- Gigabit Ethernet delivers the scalable
performance of Ethernet technology. Ethernet is clearly the most widely
understood LAN technology. With more than 85% of all installed network
connections running Ethernet at the end of 1997, Gigabit clearly offers
a good combination of price, simplicity, scalability and management
ease of use.
- Gigabit Ethernet Leverages Ethernet
Equipment Costs The goal of the IEEE 802.3z Task Force, which developed
the Gigabit Ethernet standard, was to specify connections that
delivered 10 times the performance of Fast Ethernet at very affordable
prices. Because Gigabit Ethernet leverages existing Ethernet
technologies, it also leverages Ethernet’s fiercely competitive
industry cost curve.
The Gigabit Ethernet Standard
The 1000BASE-X (IEEE 802.3z) Gigabit
Ethernet standard was ratified in June 1998, after more than two years
of intense effort within the IEEE 802.3 Ethernet committee. The key
objective of the 802.3z Gigabit Ethernet Task Force was to develop a
Gigabit Ethernet standard that encompassed the following:
- Allowed half- and full-duplex operation
at speeds of 1000 Mbps.
- Used the 802.3 Ethernet frame formats.
- Used the CSMA/CD access method with
support for one repeater per collision domain.
- Addressed backward compatibility with
10BASE-T and 100BASE-T technologies.
Because the fundamental features of the
802.3z specification have been stable during the last stages of the
standardization process, network vendors have been able to build and
deliver quality, mature products to the marketplace for many months. In
addition, numerous interoperability demonstrations have been sponsored
by the Gigabit Ethernet Alliance and other independent organizations,
giving customers confidence in using Gigabit Ethernet products in their
production networks.
This article is excerpted from “Gigabit Ethernet Comes of Age” by Bruce Tolley
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