Wide area network - SpeedyLook encyclopedia

Classification of the networks

The inter-connected systems and networks are subdivided in lans (LAN for Local Area Network ), networks known as metropolitan (MAN for Metropolitan Area Network ) and wide area networks (WAN for Wide Area Network ). This classification is primarily based on a concept of distance physical.

One speaks about LAN when the distances concerned are about a few tens of meters, more the long distance not being able to exceed the hundred meters. It is mainly the case when the systems are in the same building. Technology employed is almost exclusively the connection Ethernet on cables of twisted pairs ( twisted even English ).

When the distance exceeds the hundred meters until reaching a few kilometers, one speaks about MAN and the technique used is generally the use of fiberoptics. One currently attends the emergence of a technique of connection via waves radios (Wi-Fi) both for topologies MAN topologies LAN.

When the distance is beyond a few kilometers, technology used becomes more complex and one generally uses the services of a “operator” ( carrier in English) who undertakes the routing of the data via infrastructures that it manages. There is then business with a WAN.

Technologies used in WAN

Rented line

The point-to-point Liaison is a connection between the network of the customer and that of the conveyer who is generally made via rented lines ( leased lines , in English). At the end of each line, one places a Routeur connected on a side to the Lan of the customer and other with the infrastructure of the operator.

Commutated circuit

Connections of the type ISDN (English ISDN) have the disadvantage of being invoiced with the communication.

These 2 types of connection can use the protocols SLIPWAY (obsolete), HDLC (little used) or PPP (more running).

Packet switching

Of type ATM, they allow a flow guaranteed by FAI. This type of connection can use the protocols like:

X.25 (obsolete)
Frame Relay (in process of advanced obsolescence)
ATM (still used, in process of obsolescence)
MPLS
PBT/PBB-TE: Ethernet as a technology of transport with engineering of traffic

Known operators

The operators (English carriers) most known are France Telecom (Equant), Deutsche Telekom (DT), BT, Telefonica, COLT Telecom and well of others still.

Alternatives

Now that Internet provides a fast network WAN, the need to have its own wide area network is less crucial. It is possible to use in the place a virtual private Network (VPN), using the Chiffrement and other techniques to give the impression which the organization lays out of its own private network whereas it uses the shared infrastructure of Internet. This solution however confers a quality of service less, or at least identical to that of the connection Internet which in general has a lower availability ratio.

See too

ATM
Relay of screens
X.25
Gigabit Ethernet
PBT/PBB-TE

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