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INTRODUCTION OF NETWORK HARDWARE

NETWORK HARDWARE

INTRODUCTION OF NETWORK HARDWARE 

    The hardware used to establish a network plays a very important role in network. Various type of 
hardware, where they are used and why a particular type of hardware is used is very important to understand. The main hardware components of a network are hub, switch, bridge and router. The definition and their basic concept is described below 

NIC 
NIC stands for network interface cards. It is a card made of electronic component which works as an interface between the computer and network i.e. it provides connectivity with other resources of the network. The connectivity may be wireless or through cables depends on type of NIC used.each NIC card has a unique physical number known as MAC address.a NIC card attaches and reads MAC address on the packet while transmitting and receiving the packets. 

HUB 
 Hub is a multi port repeater that just repeats what receives at one port to all other ports. It is a central point of a star topology which allows the multiple connections of devices. It works at the physical layer of the OSI model i.e. It only provides a physical connectivity between various devices of a network and passes data to all ports no matter which device it is addressed to. In other words it only forwards the data to all devices. In brief we can say hub only performs forwarding not filtering or routing. This feature adds to congestion in the network. Sometimes a basic hub can be more than a basic hub and provides additional services (managed hubs, switched hubs, and intelligent hubs). 

Managed hub 
A network hub that has intelligence built into firmware. Typically an Ethernet hub, it responds to management queries for statistics and to commands for setting the configuration. Managed Ethernet hubs evolved into managed Ethernet switches. A network device that performs a variety of processing functions, including network management, bridging, routing and switching.(managed hub just starts working like a switch) 

Switching hub 
 Short for port-switching hub, a special type of hub that forwards packets to the appropriate port 
based on the packet's address. Conventional hubs simply rebroadcast every packet to every port. Since 
switching hubs forward each packet only to the required port, they provide much better performance. 
Most switching hubs also support load balancing, so that ports are dynamically reassigned to different
LAN segments based on traffic patterns.

Passive hub 
 A central connecting device in a network that joins wires from several stations in a star configuration. It does not provide any processing or regeneration of signals 

Active hub
 A central connecting device in a network that regenerates signals on the output side to keep the signal strong. Also called a "multiport repeater."

BRIDGE 
Bridge is a intelligent repeater (a repeater is a two port device which generates the same packets which it receives at bit level) with filter which connects two LAN or segments of the same network. It works at data layer – not physical i.e. it uses MAC address to make decisions. It acts as a ’filter’, by determining whether or not to forward a packet on to another segment or LAN .it builds a bridging table and keeps a track of devices on each segment. It filters packets, does not forward them, by examining their MAC address. It forwards packets whose destination address is on a different segment from its own .it divides a network in to multiple collision domains – so reducing the number of collisions. 

SWITCH 
Switch is a multi port bridge. In networks, a device that filters and forwards packets between LAN segments on the basis of MAC address is known as switch. Switches operate at the data link layer (layer 2) and sometimes the network layer (layer 3) of the OSI reference model and therefore support any packet protocol. In other words we can say that switch stores the MAC address of the devices with whom it is connected. It also utilizes bandwidth as per requirement and forwards the data to whom it is required thereby acts as a filter. It provides connectivity between those ports only where connectivity is required and hence maximum utilization of bandwidth is done.

Hub vs. Switch 
Shared versus dedicated channels. A hub shares the total bandwidth among all users, while a switch provides a dedicated line at full bandwidth between every two devices transmitting to each other. A hub only forwards while a switch forwards and filters both.hub is half duplex while switch is full duplex. A hub works on physical layer while a switch works on data link layer. A switch divides network into multiple collision domain while hub cannot divide the network into multiple collision domain and hencecongestion is more in a hubed network than a switched network. 

ROUTER 
Router is a device which connects two or more networks (different types too) and provides appropriate routing information to the each packet for communication .it works on network layer i e it works with the help IP address and network address. A router allows access to resources by selecting the best path. it Changes packet size and format to match the requirements of the destination network. A router has two primary functions – to determine the ‘best path’ and to share details of routes with other routers. 

BROUTER 
A device which works both as bridge and router is called brouter.

GATEWAY 
Simple router that links two networks is called gateway. This device acts like an entry /exit point of the network. It converts one protocol or format to another. A network gateway converts packets from one protocol to another. An application gateway converts commands and/or data from one format to another. An e-mail gateway converts messages from one mail format to another. 

WAP 
 In computer networking, a wireless access point (WAP or AP) is a device that connects wireless communication devices together to form a wireless network. The WAP usually connects to a wired network, and can relay data between wireless devices and wired devices. Several WAPs can link together to form a larger network that allows "roaming". (in contrast, a network where the client devices manage themselves - without the need for any access points - becomes an ad-hoc network.) WAPs have IP addresses for configuration.

WIRELESS ROUTER 
     A network device that combines a wireless access point (base station), a wired LAN switch and a router with connections to a cable or DSL service. Wireless routers provide a convenient way to connect a small number of wired and any number of wireless computers to the internet. 

    How a wireless network works*( for advance users only) 

    A wireless local area network (WLAN) is the linking of 2 or more computers with network interface cards (NICs) through a technology based on radio waves. All devices that can connect to a wireless network are known as stations. Stations can be access points (APS), or clients. 

    Access points are base stations for the wireless network. They receive and transmit information 
for the clients to communicate with. 

    The set of all stations that communicate with each other is referred to as the basic service set 
(BSS). Every BSS has an identification known as a BSSID, also known as the MAC address, which is a unique identifier that is associated with every NIC. 

    For any client to join a WLAN it should know the SSID of the WLAN; therefore, the access points typically broadcast their SSID to let the clients know that an AP is in range. 

    Data streams, known as packets, are sent between the access point, and it’s clients. You need no physical access to the network or its wires to pick up these packets, just the right tools. It is with the transmission of these packets that pose the largest security threat to any wireless network. 

THE SETUP
To setup a wireless LAN following devices are required. 
1. Two or more Wireless access point(WAP) as per requirement 
2. A 15/20 db antenna for wider coverage 
3. Weatherproof box to protect WAP and providing electric connection 
4. Wireless Adapter for client to connect PC with WAP

    Now with the help of all these hardware we will see step by step method to establish a WLAN.
 1. First of all we will have to configure each WAP. To accomplish this task first of all connect WAP with the help of an Ethernet cable to a laptop. 

2. Give power connection to WAP. 

3. Now open the internet explorer browser and in the address bar type the default IP of the WAP. The default IP Address is provided in the manual. Here for example we assume it as 192.168.0.50. Now set laptop IP as 192.168.0.51 so that connectivity takes place. Following screen will appear in the browser 

4. Now provide the appropriate password as provided by the company in the manual. 

5. After providing the correct user name and password the next screen will appear which is as follows.

6. Now run the wizard which is self explanatory.

7. Now set the new password → next → give a SSID name (a SSID can be any name) →set encryption 
as WEP→ Finish and restart to changes take place. 

8. Now again open the window using same procedure and open the Wireless →Home page

9. Now here set the Mode as WDS with AP to work the WAP both as a repeater and Access point. Generally there are three modes in setup and they are WDS(only repeater/Bridge),WDS with AP(for both function as bridge and Access point) and AP (to work as AP alone without connection with any other access point) 

10. Now set up the rest configuration as per diagram provided above and than in WDS dialogue box provide the MAC address of all other access point with whom we want to connect this Access point.(MAC address is provided on the label provided with the access point).all other access point whose MAC address will be provided will receive packets from this access point.(maximum number of access point MAC address that can be provided here depends on no of channels available in the access point).here we will also provide the shared key that all PC /Laptop will use to connect with this access point. Close the dialogue box and restart. 

11. Same steps require to be repeated in each WAP and the set up is ready to be installed. 

12. Now install all the access point at suitable distance where they have line of sight connectivity. 

13. Note that in first access point we require to provide internet connection through Ethernet cable so that all clients can access the internet. 

14. We can also change IP address as per our network suitability. 

15. Now once all access points are installed at suitable distance check in the PC where Wi-Fi network 
is available or not.


16. If available the laptop with Wi Fi enable will automatically indicate with the message that “there is 
a wireless network available” click “connect”. 

17. If it is WEP enabled it will prompt for Network key provide the same as set up in WAP and it will 
connect through the WAP.


    While we go through Wi-Fi setup process we frequently encounter certain terms like WEP, 
Shared Key, WAP, WDS etc understanding of which is must for a in depth understanding of Wi-Fi. Some of them are explained below: 
1. Wireless encryption
 The majority of home and small business networks are encrypted using the two most popular 
methods: 

WEP 
Wired equivalent privacy - WEP aims to provide security by encrypting data over radio waves so that it is protected as it is transmitted from one end point to another. However, it has been found that WEP is not as secure as once believed. WEP is used at the two lowest layers of the OSI model - the data link and physical layers; it therefore does not offer end-to-end security. It comes in 3 different keylengths: 64, 128, and 256 bits, known as WEP 64, WEP 128, and WEP 256 respectively. WEP provides a casual level of security but is more compatible with older devices; therefore, it is still used quite extensively. WEP also comes in WEP2 and WEP+, which are not as common and still as vulnerable as the standard WEP encryption. 

WPA 
Wi-Fi protected access - comes in WPA and WPA2, and was created to resolve several issues found in WEP. Both provide us with good security; however, they are not compatible with older devices and therefore not used as widely. WPA was designed to distribute different keys to each client; however, it is still widely used in a (not as secure) pre-shared key (PSK) mode, in which every client has the same 
passphrase. To fully utilize WPA, a user would need an 802.1x authentication server, which small businesses and typical home users simply cannot afford. WPA utilizes a 48 bit initialization vector (IV), twice the size of WEP, which combined with other WEP fixes, allows substantially greater security over WEP. 

2. WDS 
Wireless Distribution System (WDS) allows you to make a completely wireless infrastructure. Normally, the access points must be connected with a wire (LAN). These access points create cells allowing a wireless connection. The WDS feature allows the access points to be wirelessly connected. This feature is normally used in large, open areas where pulling a wire is restricted or not cost effective and in residential circumstances. 
    If the structure utilizing an access point is too large to cover using one AP, a second AP would be used as a wireless repeater. The WDS has forwarding functionality for extending the range of an AP. By setting up an extended service set (ESS) between access points. Stations can intersect with any AP of this ESS and move between the coverage of both APs while the higher layer network connection remains intact. 

Note: The WDS feature is not completely specified in IEEE or Wi-fi standards. Therefore interoperability between 802.11 products of different vendors is not guaranteed.

VAROIUS CONNECTORS LIKE RJ-45 AND BNC 

Registered jack-45
Registered jack-45 is a telephone connector that holds up to eight wires. Rj-45 plugs and sockets are used in Ethernet and token ring type 3 devices. 

Bayonet nut coupling 
     A commonly used plug and socket for audio, video and networking applications that provides a tight connection. Using a mount somewhat similar to the way a bayonet (knife) is mounted onto the end of a 
rifle, BNCs are used to connect a variety of different coaxial cable types. After the plug is inserted, it is 
turned, causing pins in the socket to be pinched into a locking groove on the plug. 

        There are numerous definitions of the BNC acronym, including bayonet neill-concelman (after its 
inventors), barrel nut connector, bayonet nipple connector, bayonet navy connector, baby n connector, 
British naval connector and British national connector.

    BNC’s differ from many connectors because of their snap-lock architecture, which keeps the plug firmly in its socket.




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