NETWORK CONNECTIVITY DEVICE

Network Interface Card (NIC) The network interface card is a device installed on system. That is responsible for sending and receiving data on to the network. The network card is responsible for preparing data from the system to be transport on the wire by converting electrical signal.

MAC Address: Each network card has a unique address that is burned into the card by its manufacturer . This unique address is known as a MAC address (Multimedia Access Control), and it used in the header of the packed for the source and destination address is a 48 bit addresses in a hexa-decimal format. The MAC address is made of 12 characters.

00-02-3F-6B-25-13 Manufacturer ID Unique ID

HUB HUBS are one of the most important components of a network. Because HUB act a central point for all network device to connect them.

Passive HUB: The function of a passive HUB is simply to receive data from one port of the Hub and sends it out to the other port. A passive hub contains no power source or electrical components. There is no signal processing and there is no regenerating signal. A passive hub simply attaches the ports internally and enables communication to flow through the network.

Active HUB: A active hub provide the same function as a passive hub with an additional feature. Active hub rebuilt the data before sending it to all of the destination ports on the hub. It is important to remember that UTP cable can be run in maximum of 100 meters with an active hub you can run this type of cable 100 meters on each side of hub an active hub has power source and built in repeaters to boost the signal.

Intelligent HUB: An intelligent hub works like active hub. But some external features have in intelligent hub. Active hub data generate with noise, but intelligent hub data regenerate without noise.

REPEATERS

SIGNAL GETS WEAKER WITH DISTANCE

On the pitfalls of networking environment is that the electrical signal that is travelling the wire is weakened over distance as a result of outside interface. If two systems are too far from one another, the signal is so weak that by the time it reaches the other side it is unreachable. These is where repeaters comes in. if you are using thin net is limited to 185 meters but if you want to connect two systems together that are 135 meters a part, you would replace a repeater.

The term “repeater” originated with telegraphy and referred to an electromechanical device used to regenerate telegraph signals. Use of the term has continued in telephony and data communications.

In telecommunication, the term repeater has the following standardized meaning:

1. An analog device that amplifies an input signal regardless of its nature (analog or digital).

2. A digital device that amplifies, reshapes, retimes, or performs a combination of any of these functions on a digital input signal for transmissions.

Because repeaters work with the actual physical signal, and do not attempt to interpret the data being transmitted, they operate on the physical layer, the first layer of the OSI model.

Digipeater: a Digipeater is blend meaning “digital repeater”, particularly used in amateur radio. Store and forward digipeaters generally receive a packet radio transmission and then retransmit it on the same frequency, unlike repeaters that receive on one and transmit on another frequency.

BRIDGEA bridge is a network connectivity device that is used to break the network down into multiple network segments. A bridge run at data link layer, and it used to filter traffic by only forwarding traffic to the destination network segment.

00-40-C9-C3-D2-E2

When the bridge received the initial data from workstation, is received the MAC address of workstation reside on the bridging table this way if any send data to workstation. The bridge will have an entry for workstation in the bridging table and the bridge will forward the data only to the network segment and not to the other segment.

►►Advantages of Network Bridge:-1. Self configuring2. Primitive bridges are often inexpensive3. Reduce size of collision domain by micro segmentation in non

switched networks

Segment 1: 00-0D-0F-HU-6L-99

Segment 2: 00-0F-5J-OP-9R-87

4. Transparent to protocols above the MAC layer5. Allows the introduction of management – performance information

and access control6. LANs interconnected are separate and physical constraints such as

number of stations, repeaters and segment length don’t apply.

►►Disadvantages of Network Bridge:-1. Does not limit the scope of broadcasts2. Does not scale to extremely large network3. Buffering introduces store and forward delays – on average traffic

destined for bridge will be related to the number of workstation on the rest of the LAN

4. Bridging of different MAC protocols introduces errors5. Because bridges do more than repeaters by viewing MAC

addresses, the extra processing slower than repeaters.6. Bridges are more expensive than repeaters.

SWITCHES

Switch also known as switching hub. It has become an important part of our networking today, because when working with hub, a hub sends the data to all ports on the hub, if you a large networking structure, this means that you have probably linked a few hubs together and when data is send from one system to another system, all computers see the traffic. This leads to a lot of network performance.

When you use a switch instant of a hub, the switch acts as a filtering device by associating the MAC address of the system connect to the switch with the port on the switch that the system is connected to.

24 port switch

Router

Router are layer-3 devices and are responsible for routing or sending data form one network to another. A router will have multiple network interface with each network interface connecting to a network or a WAN environment. Router Typically are used to connect the Lan to a WAN environment by the router having a network interface and aWAN interface connecting to each type of network. The router then pass data from one side of the router to the outher.

Router are a great way to filter network traffic as well, because they act as a broadcust domain. Traffic will not cross the router unless it is actually destined for a system on a remote network. Most router administrators do not allow broadcust to pass through the router.

Routers operate in two different planes :

Control Plane – in which the router learns the outgoing interface that is most appropriate for forwarding specific packets to specific destination.

Forwarding Plane-which is responsible for the actual process of sending a packet received on a logical interface to an outbound logical interface.

Brouters

A number of network environments use multiple networks protocols on the network to support different network applications or services. If you need route a data for one protocol but need the bridging funcionally for another protocol instead of buying both a bridge and a router, you can purchase a brouter. A brouter is the combination of router and bridge and it makes the decision whether it needs to bridge the data or route the data according to the protocol being used. If the protocol is non-routable protocol such as NetBEUI the data will be bridged. If the protocol is TCP/IP or IPX/SPX the routing features of brouter will be used.

GATEWAY

The other type of devices that are found in networking environments. A getway is responsible for translating information from one format to another and can run at any layer of OSI model. Depending on what information the getway translates, a typical use of a gateway is to ensure that systems in one environment can access information in another environment. For example : you want to make sure that your pc environment can access information on the company’s mainframe. When the packet reaches the gateway, the gateway strips the packet down and repackages. It so that it is understood on the other side of the gateway.

FIREWALLS

Firewall are a networking components responsible for protecting the network from outside intruders. The firewall is designed to block specific types of traffic whill allowing certain information to pass through. For example : i have a firewall that blocks any data that tries to reach my network from the internet unless it is HTTP traffic through the firewall. Because, i would like to my costomer to be able to view my website. The firewall administrator selectivelly chooses which traffic can and cannot pass through the firewall.

.....................................................................................................................................

..........................................................................................................