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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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