Types of LAN Technology
Ethernet
Ethernet is the most popular physical layer LAN
technology in use today. It defines the number of conductors that are required
for a connection, the performance thresholds that can be expected, and provides
the framework for data transmission. A standard Ethernet network can transmit
data at a rate up to 10 Megabits per second (10 Mbps). Other LAN types include
Token Ring, Fast Ethernet, Gigabit Ethernet, 10 Gigabit Ethernet, Fiber Distributed
Data Interface (FDDI), Asynchronous Transfer Mode (ATM) and LocalTalk.
Ethernet is popular because it strikes a good
balance between speed, cost and ease of installation. These benefits, combined
with wide acceptance in the computer marketplace and the ability to support
virtually all popular network protocols, make Ethernet an ideal networking
technology for most computer users today.
The Institute for Electrical and Electronic
Engineers developed an Ethernet standard known as IEEE Standard 802.3. This
standard defines rules for configuring an Ethernet network and also specifies
how the elements in an Ethernet network interact with one another. By adhering
to the IEEE standard, network equipment and network protocols can communicate
efficiently.
Fast Ethernet
The Fast Ethernet standard (IEEE 802.3u) has been
established for Ethernet networks that need higher transmission speeds. This
standard raises the Ethernet speed limit from 10 Mbps to 100 Mbps with only
minimal changes to the existing cable structure. Fast Ethernet provides faster
throughput for video, multimedia, graphics, Internet surfing and stronger error
detection and correction.
There are three types of Fast Ethernet: 100BASE-TX
for use with level 5 UTP cable; 100BASE-FX for use with fiber-optic cable; and
100BASE-T4 which utilizes an extra two wires for use with level 3 UTP cable.
The 100BASE-TX standard has become the most popular due to its close
compatibility with the 10BASE-T Ethernet standard.
Network managers who want to incorporate Fast
Ethernet into an existing configuration are required to make many decisions.
The number of users in each site on the network that need the higher throughput
must be determined; which segments of the backbone need to be reconfigured
specifically for 100BASE-T; plus what hardware is necessary in order to connect
the 100BASE-T segments with existing 10BASE-T segments. Gigabit Ethernet is a
future technology that promises a migration path beyond Fast Ethernet so the
next generation of networks will support even higher data transfer speeds.
Gigabit Ethernet
Gigabit Ethernet was developed to meet the need for
faster communication networks with applications such as multimedia and Voice
over IP (VoIP). Also known as “gigabit-Ethernet-over-copper” or 1000Base-T,
GigE is a version of Ethernet that runs at speeds 10 times faster than
100Base-T. It is defined in the IEEE 802.3 standard and is currently used as an
enterprise backbone. Existing Ethernet LANs with 10 and 100 Mbps cards can feed
into a Gigabit Ethernet backbone to interconnect high performance switches,
routers and servers.
From the data link layer of the OSI model upward,
the look and implementation of Gigabit Ethernet is identical to that of
Ethernet. The most important differences between Gigabit Ethernet and Fast
Ethernet include the additional support of full duplex operation in the MAC
layer and the data rates.
10 Gigabit Ethernet
10 Gigabit Ethernet is the fastest and most recent
of the Ethernet standards. IEEE 802.3ae defines a version of Ethernet with a
nominal rate of 10Gbits/s that makes it 10 times faster than Gigabit Ethernet.
Unlike other Ethernet systems, 10 Gigabit Ethernet
is based entirely on the use of optical fiber connections. This developing
standard is moving away from a LAN design that broadcasts to all nodes, toward
a system which includes some elements of wide area routing. As it is still very
new, which of the standards will gain commercial acceptance has yet to be
determined.
Asynchronous Transfer Mode (ATM)
ATM is a cell-based fast-packet communication
technique that can support data-transfer rates from sub-T1 speeds to 10 Gbps.
ATM achieves its high speeds in part by transmitting data in fixed-size cells
and dispensing with error-correction protocols. It relies on the inherent integrity
of digital lines to ensure data integrity.
ATM can be integrated into an existing network as
needed without having to update the entire network. Its fixed-length cell-relay
operation is the signaling technology of the future and offers more predictable
performance than variable length frames. Networks are extremely versatile and
an ATM network can connect points in a building, or across the country, and
still be treated as a single network.
Power over Ethernet (PoE)
PoE is a solution in which an electrical current is
run to networking hardware over the Ethernet Category 5 cable or higher. This
solution does not require an extra AC power cord at the product location. This
minimizes the amount of cable needed as well as eliminates the difficulties and
cost of installing extra outlets.
LAN Technology Specifications
Name
|
IEEE Standard
|
Data Rate
|
Media Type
|
Maximum Distance
|
Ethernet
|
802.3
|
10 Mbps
|
10Base-T
|
100 meters
|
Fast Ethernet/
100Base-T |
100 Mbps
|
100Base-TX
100Base-FX |
100 meters
2000 meters |
|
Gigabit Ethernet/
GigE |
802.3z
|
1000 Mbps
|
1000Base-T
1000Base-SX 1000Base-LX |
100 meters
275/550 meters 550/5000 meters |
10 Gigabit Ethernet
|
10 Gbps
|
10GBase-SR
10GBase-LX4 10GBase-LR/ER 10GBase-SW/LW/EW |
300 meters
300m MMF/ 10km SMF 10km/40km 300m/10km/40km |
Token Ring
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