Comparision of WAN Technologies

Comparison of WAN Technologies 
Introduction:Difference between SDH and SONET:
The advances technologies such as ISDN, FrameSDH is the synchronous digital hierarchy that is
Relay, ATM and SDH/SONET are being integrateduse every where apart from in the USA, Canada
for the data and voice traffic being transmittedand Japan. SONET (Synchronous optical network)
over the internet. In olden days the telephoneis the American counterpart of SDH. Designs of
lines used carried voice traffic in the form ofthis transmission technology in America begin as
analog and were know as Plain Old Telephonefar back as 1985. The SONET basic bit rate is
System (POTS), but at present the telephones51.48 Mbit/s and is named STS-1 (synchronous
and the computers use digital technology for thetransport signal). If the bit rate is transmit above
voice and data traffic. Devices like modems arean optical cable system, the signal is named as
being used to convert analog into digital and viceOC-1 (optical container)
versa. As more and more peoples are using 
internet the data and voice traffic is beingSONET Signal
transmitted over the same line. In my report I willBit Rates
focus on some of the modern technologies forSDH Signals
voice and data traffic and the devices that areSTS-1
being used for the purpose in the Wide Area51.84 Mbit/s
Network. At present the most emergingSTM-0
technology being used in the Wan is VOIP. ItSTS-3
transmits voice over the internet using the155.52 Mbit/s
packets. The users can transmit audio and videoSTM-1
over a data network. The analog signal isSTS-12
converted into digital using the modem. The622.08 Mbit/s
modem converts analog signals into small digitalSTM-4
packets to be transmitted over the network. AtSTS-48
the receiver end the data is demodulated and the2488.32 Mbit/s
file is converted into an AVG file. This procedureSTM-16
is being used in VOIP, Video conferencing andSTS-192
streaming of audio and video clips on the internet.9953.28 Mbit/s
With this the WAN technologies are emerging andSTM-64
many WAN devices are being used. 
 Table: Levels in Hierarchy
WIDE AREA NETWORKS: 
Several Local Area Network connected is knowPublic Data Network:
as Wide Area Network. This helps in transmittingThe people around the world use public network
data to longer distances using a single network.to send and receive data which is also know as
Better example for this would be differentinternet. If a user is making a call using the
branches of a company around the world areinternet then its priority will be high because the
interconnected using the Wide Area Network. Theuser is using an expensive technology. If its
branches use LAN in the branch and WANsecurity and reliability is ignored then more and
between different branches which helps themore private networks will be formed by
business to grow at a faster pace and withdifferent companies which will lead to congestion
security.of the network The common carrier subscriptions
 which own telecom services are known as public
WAN DEVICES:networks. It supports the transmission of voice
The various WAN devices available in the markettraffic over the internet using the modems
are being manufactured on the lines of reliabilitythrough the telephone sockets and gain
and security of the network. Some of them areautomated access to users around the world. In
 this there is no wastage of bandwidth as the calls
Router:are being made over the internet and this will be
In the network a router helps to connect one ora reliable and suitable for small companies
more than one computers. Normally for home 
users they are helpful in taking a single broadbandATM:
connection and spreadingATM is the short form for Asynchronous
 Transfer Mode. Circuit switching usually requires
 that packets are placed into position in recurring
Figure: Routerit to other computers. Backbone offrames, i.e. synchronous, in time, in step according
an internet is usually by industrial routers whichto use and/or network clocks. Asynchronous
are used in the telecom industry. Each router hastransmission allow cells to be placed anywhere in
a table configured to make connections which leadthe data stream. ATM at present has speeds of
to a group of IP addresses. The routing table also155Mbps (OC-3 ports), 622Mbps (OC-12 ports), 1.2
have the rules to handle different types of traffic.Gbps and 2.5 Gbps. Since the cells are rigid in
Switch:length (53 octets, or bytes) quite than variable
A switch is every so often called a 'intelligent hub',such as an Ethernet frame, they can be switch in
and at the present that they are no longerhardware to a certain extent than software and
considerably more costly than the hubs they havethese accounts for the high speeds that can be
roughly replaced them completely. A switchattain than Ethernet, Token Ring and FDDI.
works alike as a hub, with the aim of to connectATM is very lithe and allow the transmission of a
devices to let them to work as a single segment.variety of media type such as voice, video, data
However, it does not repeatedly transmit trafficfiles etc. all demanding the network in changed
to each and every port. Whenever a frame ofways, video, for example can be extremely
data enters into the switch, it save the physicalsubject to a sudden slowdown in network routine
address (MAC address) and the port it comeas altering speed video is very disturbing. ATM
from in its MAC address table. Then it checks theallows committed circuits with certain bandwidths
target MAC address in the table, and if itand differing needs to be set up at the same
recognises it sends the frame to the suitable port.time ( Quality of Service (QoS) can be locate up
If the address is not the table, or address is aand is certain at connection stage by means of
broadcast address (intended for every machineparameter such as delay, delay jitter and error
on the local network), then it do the equivalent asrate base on the function and the position of the
a hub and transmits the frame throughout everynetwork at the moment of connection. Two
port apart from the originating port.priority for traffic are defined; High priority and
Hub:Low priority. Low priority traffic force is leftover
A hub is a tool for connecting various Ethernetif around are switch congestion trouble. Particularly
devices (usually PCs) to outline a single segment -voice and video traffics include to be transferred
a part of a network that is unconnected fromby means of previous methods such as MPLS
other parts of the network. It has several portsover ATM and IP over ATM, where QoS maintain
throughout which devices are joined, and while itadvantages of the ATM are subjugated in
receives data it send it out over through everyexacting (Cemal Kocak, et.al, 2007). There is no
port apart from the one it come in through.joint media or conflict based protocols in ATM,
Initially Ethernet networks use coaxial cables. Eacheach machine has 155Mbps all to itself. In ATM
computer was fixed with a transceiver, which isyou be able to multiplex 'cell streams' so as to
connected straight into a long part of coaxial cablemay be for totally different application, the
- a bus. This means that the traffic flowing on thestructure works in 'connection oriented' form
network is visible to every one on the network.thereby guarantee cell sequencing for those cells
Modem:in a exacting connection.
The short form for modulator and demodulator isFrame Relay:
Modem. It converts digital frequencies of theIt is developed by the values or technology base
computer in to analog to make it transmit overon ISDN (Piliouras, 2005). The communication is
the telephone or cable lines. At the receiver endamong end users by following the interface of
the modem successfully demodulates the analogpublic network and private network (Taylor,
into digital and gives it to the computer to carry2000). It handles high traffic on internet at high
out appropriate functions.speeds and on the whole handles data networking
 issue at high speed by functioning on following
Figure: Modemprinciples:
 Solution for errors like congestion occurs,
 discarding frames and means to improve errors
 at end user method. It works on applications of
WAN FACILITIES:data and is based on packet switching (Smith,
ISDN:1996). The data is distributed into frames of
The replacement for old age analog technology isvariable length similar as in packet switching, which
the ISDN. It was implemented to create a moreis sent to target through frame relay networks.
reliable and faster transport mechanism. It isThe difference between frame relay and packet
cheaper than a leased line and it takes seconds toswitching is that frame relay is second layer
install it. The standard ISDN, Broadband ISDN isprotocol of OSI where as packet switching is third
the version most people are aware of which islayer protocol but frame relay is quite
the ATM.straightforward compared to packet switching
The end equipment protocol is defined by the ITUlinking locations all the way through access circuit
I and the switch/network protocol is defined byto networks (Green, 2000). Carrier information
the ITU Q series.rate (CIR) is the element which is used to charge
Structure of ISDNand it guarantees the transporting the carrier
The protocol model for ISDN is represented in thethrough, Access Circuit cost is classify by LEC and
following diagram:port speed which is a manifold of 64 Kbps.
  
 CONCLUSIONS:
Figure: Structure of ISDNThe idea of information backdrop, issue
 concerning technology, in force scenarios and
SONET/SDH:advance to protocols management for WAN
With the beginning of PCM tools in the 1960s,technologies and a lot of unresolved promotion
communications networks are steadilyand technological questions concerning coexist of
transformed to digital technology above the nextconventional communications of voice. The WAN
few years (Werner, Fundamentals and SONETtechnology should further develop earlier than the
testing). To deal with the stipulate for ever highconsiderable possible acceptance and also
bit rates, a multiplex hierarchy called thecustomer service and billing methods. Additional
plesiochronous digital hierarchy (PDH) evolve. Thedetermine execution of WAN and efficient
bit rates begin with the fundamental multiplex ratestructure of billing method for calls using VOIP
of 3 Mbit/s with additional stages of 8, 34 andsystem and also sophisticated procedures.
140 Mbit/s. The 1980s see a start in the growthAdvancement or adoption of WAN technologies
of the synchronous digital hierarchy (SDH), withwill in the end resolve services, price efficiency
the purpose to eliminate the disadvantage inbuilt inand Quality of Service. The trouble for session
PDH. SDH bring the subsequent advantages totimeout, issue of reliability and solution of feeble
network provider.slow link have to be resolve. The mixing of data
1. High transmission ratesprotection system is necessary for errors
Transmission rates of up and about 10 Gbit/s cancorrection and dependable to run the arbitrary
be achieve in current SDH systems.data or voice traffic over the internet internet.
1. Simplified add and drop function 
When compared to the old PDH system, it is a lotReferences:
easier to take out and insert low-bit rate channelsCathrine Paquet, 2001, "Building Cisco Remote
on or after or into the high-speed bit streams inAccess Networks" Cisco Press CompTia, Que
SDH.Publishing.
1. ReliabilityCemal Kocak, et.al, MPLS over ATM and IP over
Modern SDH networks consist of variousATM methods for multimedia applications,
repeated back-up and repair mechanism to dealComputer Standards & Interfaces 31 (2009),
with system faults.pp 153–160, 2007.
1. Future platform for advanced services. 
At present, SDH is the suitable platform for theDennis & Fitzgerald, 2005, "Business Data
advanced services ranging from ISDN, POTSCommunications Networking", John Wiley &
through to data communications (LAN, WAN).Sons.
1. Interconnectivity 
SDH makes it easy to install or set up newGupta C P, 2006, "Data Communications and
gateways in between various network providersComputer Networks", India, Prentice Hall of India.
and SONET systems. 
 Huggins D, Ferguson B, 2002, "Designing a
 Windows Server 2003 Active Directory and
 Network Infrastructure", Que Publishing.
Figure: SDH Layer Model  Accessed 5th May 2009.