has evolved to meet the increasing demands of packet-switched
networks. Now see what Gigabit Ethernet has to offer. by Mahesh
its inception, Ethernet has been a popular networking protocol.
High-speed data, voice and video transactions on a single
network are becoming the choice of enterprises. They are looking
for cost-effective solutions that will provide greater speed
and more bandwidth. A favorable option is to move to Gigabit
What is Gigabit Ethernet?
Gigabit Ethernet is an expansion of the popular 10 Mbps (10BASE-T)
Ethernet and 100 Mbps (100BASE-T) Fast Ethernet standards
for network connectivity. It builds on top of the Ethernet
protocol, and increases speed tenfold over Fast Ethernet to
1000 Mbps, or one gigabit per second (Gbps). This protocol
was introduced by the 10 GEA (Gigabit Ethernet Alliance) in
June 1998, mainly for use in high-speed local area network
backbones and server connectivity.
The main purpose of Gigabit Ethernet is to build on the existing
installed base of Ethernet and Fast Ethernet. The idea is
to facilitate a high-speed network without forcing customers
to throw away existing networking equipment. The earlier Ethernet
specification mainly defined frame format and support for
CSMA/CD (Carrier Sense Multiple Access/Collision Detection)
protocol, flow control, full duplex and management objects,
as defined by the IEEE 802.3 standard. Gigabit Ethernet conforms
to all these specifications.
Why is Gigabit Ethernet necessary?
The main circumstances that are driving enterprises or organizations
to move to Gigabit Ethernet is the increase in Internet and
Intranet traffic. Some of the factors that are contributing
to this explosive growth are:
A rapid increase in the number of network connections
Deployment of bandwidth-intensive applications such as high-quality
video and voice
Rise in Web hosting and application hosting traffic
Increase in the connection speed of each end-station architecture
Gigabit Ethernet makes use of a combination of proven protocol
technologies like the original IEEE 802.3 Ethernet specification
and the ANSI X3T11 Fiber Channel standard. Leveraging these
two technologies helped in taking advantage of the existing
high-speed physical interface technology of Fiber Channel
while maintaining the IEEE 802.3 Ethernet frame format, backward
compatibility for installed media, and use of full- or half-duplex
To support the ever increasing bandwidth needs, Gigabit Ethernet
also incorporates enhancements that enable fast optical fiber
connections at the physical layer of the network. It also
provides a tenfold increase in MAC (Media Access Control)
layer data rates to support video and voice, complex imaging
and other data-intensive applications.
What media will support Gigabit Ethernet?
Gigabit Ethernet standards call for media support for multimode
fiber-optic cable, single-mode fiber-optic cable, and a special
balanced shielded 150-ohm copper cable.
1000BaseSX (short-wave laser) and 1000BaseLX (long-wave laser)
laser standards are supported over multimode fiber. Two types
of multimode fiber are available: 62.5 and 50 micron-diameter
fibers. Long-wave lasers will be used for single-mode fiber,
mainly because this fiber is optimized for long-wave laser
transmission. There is no support for short-wave laser over
In case of shorter cable runs of 25 meters or less, Gigabit
Ethernet will allow transmission over a special balanced shielded
copper 150-ohm cable. This is a new type of shielded cable
and should not be confused with unshielded twisted pair (UTP).
There are two main differences between Gigabit Ethernet and
previous versions of Ethernet. First is the inclusion of a
long-haul (40+ km) optical transceiver or physical medium
dependent (PMD) interface for single-mode fiber that can be
used with either the LAN physical layer (PHY) or wide area
network (WAN PHY) for building metropolitan area networks
(MANs). The second is the WAN PHY option, which allows 10-Gigabit
Ethernet to be transparently transported across existing SONET
(synchronous optical network) OC-192c or SDH (synchronous
digital hierarchy) VC-4-64c infrastructures.
What after Gigabit Ethernet?
The 10-Gigabit Ethernet standard extends the 802.3 protocols
to an operating speed of 10 Gbps and also expands the Ethernet
application space to include WAN links. This new standard
will provide for a significant increase in bandwidth while
maintaining maximum compatibility with the installed base
of 802.3 interfaces.
Similar to 1000BASE-X and 1000BASE-T Ethernet model,
10-Gigabit Ethernet continues the natural progression of Ethernet
in distance and speed. Since it is a full-duplex only and
fiber-only technology, it does not need the carrier-sensing
multiple-access with CSMA/CD protocol that defines slower,
half-duplex Ethernet technologies. Overall 10-Gigabit Ethernet
remains true to the original Ethernet model.
While Gigabit Ethernet is currently being deployed over tens
in private networks,
10-Gigabit Ethernet will be mainly used by network administrators
as a cornerstone for network architectures that encompass
LANs, MANs and WANs using Ethernet as the end-to-end, Layer
2 transport method.
As with Gigabit Ethernet, the 10-Gigabit
standard supports both single-mode and multi-mode fiber mediums.
But in 10-Gigabit Ethernet, the distance for single-mode fiber
has been expanded from the 5km that Gigabit Ethernet supports
to 40km in 10-Gigabit Ethernet.
Lets take a look at some of the areas were 10-Gigabit Ethernet
can be put into use:
Higher performance in LANs: Traditionally, Ethernet
technology has been deployed for high performance LAN environments.
Now with 10-Gigabit Ethernet, the LAN can reach farther and
support bandwidth starved applications.
With 10 Gigabit backbones installed, enterprises will be able
to provide Gigabit Ethernet service to workstations and, eventually,
to the desktop in order to support hungry applications such
as high-end graphics, streaming video, medical imaging, and
centralized applications. This technology will also provide
lower network latency due to the speed of the link and over-provisioning
bandwidth to compensate for the bursting nature of data in
Increased velocity in MANs and SANs: Deployment of
Gigabit Ethernet as a backbone technology for fiber metropolitan
networks has already been seen. Now with 10-Gigabit Ethernet
interfaces, optical transceivers and single-mode fiber, service
providers will be able to build links reaching 40 km or more.
Additionally, 10-Gigabit Ethernet, can now offer superior
data carrying capacity at similar latencies to many other
storage networking technologies including 1 or 2 Gigabit Fiber
Channel, ATM OC-3, OC-12 & OC-192,Ultra 60 and HIPPI (High
Performance Parallel Interface). Applications like remote
backup, disaster recovery and storage on demand can be easily
extended to 10-Gigabit Ethernet.
WANs: Using 10-Gigabit Ethernet, network service providers
and ISPs will be able to create high-speed links at a very
low cost, between co-located, carrier-class switches and routers
and optical equipment that is directly attached to the SONET/SDH
cloud. Along with 10-Gigabit Ethernet, the WAN PHY will also
allow the construction of WANs that connect geographically
scattered LANs between campuses or POPs (points of presence)
over existing SONET/SDH/TDM networks.
support for Gigabit Ethernet
10 Base T
Ethernet 100 Base T
Ethernet 1000 Base x
2 km (fd)
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