Wide Area Network (WAN) and technologies

WAN is built using the switches and packets which is able to extend over a large area or distance or many other computer. It is large number autonomous computers that are allocated over a large geographical area. WAN is expanding to a long distance and many other computers. In WAN switches are a small computer with their network interfaces, memory and program which are committed to packet switching function .These packet switch connected to a computer in many ways, such as it connect to the computer and other packet switch, consistently on high speed connections to other packet switches, lower the speed to computer.These packet switches are combined to make WAN .WAN does not need a balance or regular connection i.e each switch is connected through one or more other switch and one or more computers.Thestore-and-forward technology help to deliver the data packets from one computer to another. The switch which has internal memory stores incoming packet and forward the packet to the other switch or computer. If the outgoing connection is busy it hold the packets in a  queue.

The WAN Technologies are:-

ARPANET

ARPANETcontains a research tool on packet switching technologies, which is used to share the resources for the Department  of Defence's contractors.It is based on a packet- switch nodes by using the 56 Kbps leased line across the U.S and western Europe .It is  treated as the development of many algorithms and internet technologies and their latest idea. It was founded by Advance Research Project Agency (APRA)and therefore started in the 1960s. It was organised by the US Defense Department and it named as an ARPANET . The ARPANET network interconnect to a research centers, government location and soon becomes the popular research association of email and other service.

X.25

 X.25 network is used to communicate with each other and used a remote device over a high speed digital links without the leased lines. It uses a protocol layer 1 to 3. X.25 is a connection-oriented packet switched networking protocol from ITU-T  which is also known as a CCITT.  It is used for time sharing and terminal connection. It has low cost as it provides virtual high speed digital network.Thestore-and-forward data packets switching provide the speed matching, excellent flow control and other communication device which is not needed to use in same line speed.

Characteristics of X.25 network are:-

The agenda of transmission control can be changed .Speed can be communicated with each other of a different terminal. On a single physical line multiple logical channel is set.

Integrated Services Digital Network (ISDN) 

ISDN depend upon adapters at both the end of the transmission. ISDN provide a fast speed by using an ISDN adapter in place of moderm.  It is a set of CCITT/ITU standards for digital transmission over a general telephone copper wire and other media. It is adequate to deliver a high data rate of a widespread network to transfer a multimedia data. It is an architecture network, which is used to convey the digital information by using the digital technology to convey information from the various multiple networks to the end user .The information is end-to-end digital. 

Characteristics of Integrated Services Digital Network (ISDN) are:-

ISDN based on ATM standard work as a straight network for the broadband. It offers apoint to point delivery. The network is accessible and interconnected for multimedia.The data rates are different from 64 kbps upto 2 Mbps popularly available it can help to fulfill the needs of transport multimedia and is helpful for the analog modems. It can increase the to transfer  the  information and ended with internet or remote LAN connection, especially for the high media like audio or vedio, graphics, and other application then run on the LAN very easily.

There are two types of ISDN service are:-

  • Narrow band ISDN:-Narrow band ISDN service presents the circuit switched voice, circuit switched data, low and high speed packet. It works on a digital service where the transport speed are 1.544 Mbps or less. It establishes a connection and maintain the data connection  by using out-of-band signaling.
  • Broadband ISDN Service:- The broadband ISDN service can be in the form of a Frame Relay, SMDS or ATM .It can excess 1.544 Mbs. The ISDN  is accessed over one or two  services, named by the CCITT as the Basic Rate Access (BRA) and Primary Rate Access (PRA). The speed range of the broadband service is upto 25 Mbps up to the gigabit range.

Frame Relay

Frame relay creates a long-lasting virtual circuit or a switched virtual circuit.It can support a various user over the same line. Frame relay is a simple form of a packet switch as it expands  up to X.25 packet switch which help to reduce the network delay, protocol overheads, and the equipment cost. In the X.25 switching the error correction is done on end-to-end basis instead of using link to link basis. It is the simplest form of packet switching which offer a high speed of transmission and it is generally used to give direction to the protocols such as IPX or TCP/IP and to carry asynchronous traffic or other voice data. There is not any security of data integrity but the Frame relay switches packets end to end are faster.

Characteristics of Frame Relay are:-

 Frame relay is flexible in length and it is up to 4,096 bytes. It istreatedas theBroadband ISDN service. Frame relay service transport the data and it is connection service which means that each data packet are passing through the network which contain all the information of the address. It provides the speed from 56Kbs up to 25Mbsand the most used speed for the service are 56Kbs and 1.544Mbs. The Frame relay cost is low and effective, it is much faster than X.25 with least network buffering.

Cell Relay

Cell Relay is used to transfer high speed data it uses a transmission technology, which is referred  to as Asynchronous Transfer Mode (ATM). It is also known as cell due to the data transmission unit at a fix length of data.It supports high speed transmission and multiplexing transmision. It correlate the first two layer of OSI model.

Asynchronous Transfer Mode (ATM)

ATM routing is introduced as a self-routing as it provides the high speed, low-delay multiplexing and switching network to control any type of traffic like voice data or video application. It performs on a single technology for voice,video and data. ATM supports the multiple speed ,traffic and quality of service which match to applications. ATM cells marked for the user and a approve a delivery at the other end with a high credibility and low delay. ATM divides the multiplexes and a user traffic into a small fixed length of a unit  which is called cells and it is used to reduce and control  delay routing within the network process by the hardware.

Characteristics of Asynchronous Transfer Mode (ATM)  are:-

The transport speed of ATM is about 155Mbps and 622 Mbps. ATM is flexible service and the application size is of 53 bytes. The variety of applications are running on ATM Network which are allowed by the small cell size and it includes voice, video ,and the data. Other service such as Continuous Bit Rate service such as traffic to flow over a network provided by the small cell size of ATM .whereas the Frame Relay and SMDS cannot guarantee this level of service. 

 


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