Introduction
Circuit switching was first traditionally offered by the telephone system, in which the low or high capacity for any type conversation is saved on each and every switch with the help of a trunk line among the two subscribers. Although anyone face any type of difficulty to get a dial tone during any natural disaster days or on any occasion, but once the circuit is setup the user will not face any kind of difficulty while he is talking.
Circuit switching is one of the best methods for voice, in any type of conversation when one of the two persons is talking more as compared to other one; the capacity of full duplex is being used. As compared to this full duplex the data traffic is bursty, with high speed burst or short speed burst.
There are two types of circuits provided by PSTN:
- Dial up circuits
- Leased line circuits
Main body
Dial up circuits is one of the important circuit based on modem data transmission although it is slow. Where as leased line circuits which are also termed as private line circuits are the permanent circuits which are always on, and has a speed of 56 kbps. Its number of voice calls are several due to multiplexing.
Analogue to digital conversion is only possible due to the process of multiplexing. Multiplexing comprises of different types, frequency division multiplexing (FDM) is the one which is used for analog to digital conversion.
Analog to digital conversion of two steps:
- Bandpass Filtering
- Sampling
In Bandpass filtering first the analog voice signal is transferred from the subscriber to the filter at end office switch in the form of analog electrical signal.
While in the process of sampling the intensity of the signal is measured by the codec.
Another most important conversion is digital to analog conversion (DAC). In this conversion the digital signal arriving from the PSTN core is transferred first to BAC at end office switch and then these analogs signals are generated to the subscribers. The sound of these signals is very smooth because of the high sampling rate.
In both the above mentioned processes the end office switch plays a very important role, it is also known as class 5 switch because a 5 class switch hierarchy is used by the telephone network and these switches are at the lowest level in the hierarchy.
1G system generally termed as first generation system which is most popular and recognized in cellular systems was introduced in 1980’s. The first generation cellular system is consider as one of the best well recognized and an authentic cellular system which was used world wide in past few years. One of the best reason that why most of the people use this cellular system was that this cellular system gives best result and apart from this it also provides analog voice signaling system.
Apart from the analog voice signaling the first generation cellular system which is also termed as 1G was recommended as the best phone because it provides the best quality in providing analog voice signaling.
On the other hand, there is a second generation cellular system which is now consider as the best cellular technology system which most of the people use today. One of the best use of the second generation 2G cellular system is that it uses digital transmission. Now there is no problem of wires, you can carry your cellular phone anywhere you want and you can, you can easily communicate with anyone you want.
Digital transmission is now consider as one of the best service in any cellular system as with the help of it one can move easily along with his cellular phone and can easily communicate with the help of digital transmission.
GSM generally termed as GLOBAL SYSTEM FOR MOBILE COMMUNICATION is now used in the entire world. Moreover the 2G cellular system also works on the principles of GSM. The 1G cellular system has no option of GSM and it does not contain any modern facility of GSM and this is the main reason that why 2G is the popular as compare to 1G cellular system. Because of the use of the GSM in 2G cellular system now it is easy to communicate. This widespread promotion allows the roaming with all the cell phone which contains the facility of GSM. Because of the unavailability of GSM in 1G cellular system, the system does not allow the facility of roaming.
There is the availability of GSM in 1G cellular system but of low KHz. As in 2G cellular system GSM uses 200 KHz whereas in 1G cellular system GSM use only 30 KHz.
Now the latest and advanced technology in the cellular system is 3G cellular system. In third generation cellular the most authentic system is termed as CDMA CODE DIVISION MULTIPLE ACCESS. It was decided that not to terminate the use of GSM and along with this they introduced one of the latest technology termed as CDMA, so that was carrier can select that which technology should he use.
Each generation cellular system is different from one another as 2G allows 200 KHz on the other hand 3G allows 1.25 MHz. these different type of cellular systems are used in order to provide better and better facilities to the users. So that they can decide that which system is best and what they should use.
All the cellular systems are working at their best, some helps a lot in the operation of wireless system, whereas some hurts in different ways. Now the most popular cellular system is G cellular system which is now being used all over the world and it is providing better and better results so that the users can work and can get to know whatever they want to know without facing any kind of problems.
VOIP which is termed as VOICE OVER IP is one of the new technology introduced in telephone service system. VOIP is the well recognized cellular system with the help of which now it is easy to communicate without suing any over circuit switched networks. VOIP is the best ever used transmission of the telephone service signals over IP internets.
IP technology is another name of VOIP.
Now as this is a modern technology world, media is growing and making various types of advancements VOIP is the most popular technology as it with the help of media gateways connect the ordinary telephones to the IP telephone with the help of the public switched telephone network. Instead of making simple connections the media gateway also helps in converting the signals between IP telephone system and the PSTN. (name , year)
VOIP is making advancements day by day as first VOIP was just termed as voice over IP but now due to the latest advancements now VOIP is also termed as video over IP. Now it is very easy and simple to communicate with one another with the help of camera. Just attach a camera to any multimedia pc you can communicate with one another by hearing and along with this people can see each other. This kind of communication is one of the best known type communications. Video VOIP also allows the user to download video files or programs. VOIP is also the best service for making calls between different sites. As making international calls is very much expensive so VOIP provides the better service to make calls via internet.
VOIP helps a lot in saving money as it provides low rates to call from one place to another through internet. Now many companies are using this VOIP service in order to make calls as it is cheap in rates and give better results.
VOIP use best technology. One of the most advanced technologies is termed as speech codes. This speech codes helps in converting analog voice into digital signals.
Signaling in VOIP is one of the best technologies ever used. For the purpose of the transport of voice communication RTP is used.
Since 1970’s people are using different types of telephone modems to communicate with one another. Now in order to communicate with one another computer is the best source ever used. In past few years most of the people use telephone cables to connect the internet and to communicate with one another. The telephone modem is widely used in order to transfer the digital computer signals into analog computer signals.
Modem plays different roles. There are three main steps involved which are:
- Modulate
- Demodulate
- Amplitude modulation
In the step of modulate the telephone modems converts digital computer signals, they convert the digital signals into analog signals.
After this the procedure of demodulation occur in which analog signals are converted into digital signals.
In amplitude modulation the modem conveys analog signals in loud amplitude.
WAN “WIDE ARE NETWORK” is built up by most of the companies to work at their level best. Most of the companies provide lease circuits to the end user companies in order to carry out their internal data.
In other words we can say that WAN add up their own switching system, carry telephone circuits in lease and apart from this it offers networking service in data form.
There are three main purpose that why companies built WAN:
- To provide better remote access to customers who are traveling or working at home.
- To provide a link with two or more sites who are using same corporation.
- To provide better access to the internet.
As compare to WAN, LAN requires high cost and low speed. LAN is used within a particular area but when there is a need to build a network in a wider area WAN is consider as the best area network and this is the reason that why most of the companies use it.
One can build LAN because he is using it within his home but there were very shocking news related to the LAN as it requires a lot of cost, its speed was very much low.
Whereas WAN provides best speed at low cost and with the help of it one can communicate easily where he want.
WAN provides best service, best technology and apart from this it provides best speed.
One can share any type of information from one place to another if the one is using WAN service.
There are two types of topologies:
- Full mesh topology
- Pure hub and spoke topology
The full mesh topology ables the users to use drect connections.This helps when one link fails to connect so that the work can be continue and there will be no problem.
Now as everyone knows that the number of sites are increasing day by day so because of this growth the cost of full mesh topology also increases.It is termed as one of the most expensive topology.
On the other hand the pure hub and spoke topology is also used. In this type of topology all communications and interference is done with the help of one site, no more sites are needed for any kind of communication. Because of the use of one site the cost of pure hub and spoke topoplgy is also less as compared to the full mesh topology. If the line fails there is no alternative method to continue the connection.
As we are aware of the working conditions of the two topologies, the most superior topology is the full mesh topology. As it requires two or more sites to communicate and if one connection fails the connection will be continued with the help of other alternatives but besides all this there is one major disadvantage of this topology which is due to the use of two or more sites for the purpose of communication, that is the cost of this topology is very much high. It requies a lot of cost in order to continue the connection for a lasting period.
VPMs “THE VIRTUAL PRIVATE NETWORKS” is also termed as the most attractive transmission of the internet.
As everyone is aware from this situation that many sites are connected to the internat all day and night. Because of this long term connection the firms have to pay the attractive fees to various ISPs. The fee paid to ISPs is more attractive as compared to the fee which is paid to PSDN vendors.
Everyone knows that internet is a place where your data is not fully secured that is the reason why internet is termed as a non secured environment. VPNs is a network which use internet with additional security in order to transmit data.
The cost of VPNs is very low as compared to other networks. It is fully managed with the coorparation. Along with this there is a remote access VPNs link for the use of remote users.
There is site to site VPNs available for LAN users at different sites. Apart from this there host to host VPNs which is used to link to the host directly.
There is VPNs security technologies available for the VPN users:
- IP security is available for any type of VPN with high form security.
- SSL/TLS is also available for low cost transmission.
Three basic types of VPNs are:
- Remote access
- Host to host VPNs
- Site to site VPNs
IP security is considered as one of the most complicated technology for VPNs technology. It provides security for all the upper protocols.
If IP security is in use then, there is no tension. Your work ,data will be fully secured due to this IP security.
IP security has two modes of operations:
- Transport mode
- Tunnel mode
The transport mode provides full form of security to all the computers, but if you are using windows older than 2000 you should install the windows upgrading system. In contrast in the tunnel mode the connection is only available within two sites only.
The simple VPNs comprises of the following types of security.
- SSL
- TLS
SSL is termed as SECURE SOCKET LAYERS which was introduced by Netscape and was latter taken by IETF and was then renamed as TLS TRANSPORT LAYER SECURITY.
Conclusion
Now it is observed that all the systems which are working via VPNs are fully secured and there will be no harm when you share or use your data.
MAN which is termed as METROPOLITAN AREA NETWORKING includes there suburbs. It is still very new and most of the people are unaware from its working and all functions. But apart from this it is spreading slowly. It is noticed that MAN will be the network with a very high speed but apart from this its cost is very high and most of the people are unable to buy it.