Statistics have shown that there are over 10 million broadband connections in the UK. In December 2005, it was recorded that 9.792 million broadband connections were subscribed to in the UK and within three months leading to that December the broadband rate was recorded at 70,000 per week. There are several subscription methods to broadband services, we have:.
Direct Subscription Line (DSL):
DSL is majorly used to bring broadband services to homes and transmit voice, data, video and 3D effects over ordinary copper phone lines. It has a high speed internet connection and there is no delay at all as it is always online like LAN connections.
DSL is subcategorized into:
- i. HDSL (High Bit-Rate Digital Subscriber Line): It transmits data between a corporate server, the telephone company and the customer. It is one of the earliest versions of DSL.
- ii. IDSL is a system in which data is transmitted at 128 Kbps on a regular copper telephone line from a user to a destination using digital transmission.
- iii. Symmetric Digital Subscriber Line (SDSL): it runs over just one pair of copper wires.
- iv. Asymmetric Digital Subscribers Line is most popularly used for home subscribers. Its internet speed is high but it has a slower upload rate.
WIDE AREA NETWORK (WAN)
Wide Area Network is a network that has a large global coverage and is basically used to link other Local Area Networks (LANs).It is safe to say that WAN is a primary network board and it is operated with its own technology. WAN comprises of:
CPE: This has a subscriber premises called Customer Premises Equipment (CPE). Here the subscriber to CPE may purchase or lease the CPE from its service provider. The CPE is then connected to the service provider’s central office with a local loop (i.e. connecting with a copper cable)
DTE/DCE: Data is usually connected to the local loop by means of Data Circuit Terminating Equipment (DTE) or Data Communications Equipment (DCE). The DTE/DCE links the data to the WAN cloud.
The Local Loop enables operators’ direct access to their own equipment to offer broadband and other services which allow them connect to homes and businesses. Local Loop can carry data exceeding the 3.4 kHz upper limit. Wide Area Network (WAN) hardware includes routers, switches and modems amongst other accessories. The major hardware components below are explained in detail below:
Routers This electronic device links the LANs to the WAN and disseminates messages between both networks. It sends across signals using IP Addresses and operates in Layer 3. IP Addresses appear in decimal form (e.g. 184.108.40.206) for easy understanding but the language of computers isusually in binary form. There are four numbers that separate an IP Address which is known as Octets. Octets are in two forms i.e. Network and Host. The purpose of each of the Octets is to assign IP addresses to each network. These Octets are in three major classes A, B and C. Each class consist of eight bits and when put together they total up to 32bits. The Class “A” IP determines the network and the rest of the classes are hosts to the network. Multiple networks can be created within Classes A, B and C by sub-netting. The Local Area Network (LAN) uses the subnet mask and so it is important to subnet IP addresses in order to forward messages to other LANs. A subnet mask of class C appears in this format 255.255.255.0
Switch: The switch directs the data to a specific location. It operates in Layer 2 and sends across signals using MAC addresses to the accurate location.
Modem: It is also known as modulator/demodulator and can link several computers together using telephone lines. Modems can transmit and receive signals digitally and by analogue. Modems are operated in Layer 1
Wide Area Network (WAN) uses OSI model in Layer 1 and Layer 2. Layer 1 operates the electrical and mechanical connections while Layer 2 directs the encapsulated data to its destination. IP addresses sent across are usually encapsulated (i.e. wrapped up data). Signals can also be sent across by Packet and Circuit Switching. Preference is given to packet switching over circuit switching because it is cost efficient even though circuit switching is considered to be more modern and effective.
Circuit Switching: Terms associated with Circuit Switching include: Frame Relay: it transmits data at low cost between Local Area Networks (LANs). An example of a network that uses Frame relay is ISDN (Integrated Services Digital Network) which is used to transmit voice, data and video networks across a telephone Basic Rate Interference (Small businesses utilize this for internet connectivity); and Primary Rate Interface (PRI). It transmits voice and data between two locations.
Packet Switching It dissects messages in smaller bits and the messages are sent over the internet. With packet switching several messages can be sent through the same network and at the same period. An example of a packet switching network is Asynchronous Transfer Mode(ATM) and Packet Switching Data Network (PSDN). ATMbreaks data in specific sizes. PSDN is a data communication network and it doesn’t transmit signals like regular telephones.
Routing means transmitting data between several networks. This is usually done by routing protocol. Routing protocol determines how message is passed between the networks and is in various forms:
Routing Information Protocol (RIP):
It’s a protocol that was commonly used for internal networks and it communicates and adapts changes to bridge the distance between the network routers. It is known to experience crashing issues.
Distance Vector (a.k.a Bellman-ford Algorithm):
is known to pass information to its neighbours about its routing table. Cisco Company invented a Distance Vector known as IGRP to measure and compare routes. Messages are passed between routers at periodic intervals.