Network Topology And Devices

NETWORK

A Computer Network, or simply a Network, is a collection of computers and other hardware interconnected by communication channels that allow sharing of resources and information. A network is a group of devices connected to each other.

Networks may be classified into a wide variety of characteristics, such as the medium used to transport the data, communications protocol used, scale, topology, benefit, and organizational scope.

NETWORK CLASSIFICATION

A local area network (LAN) is a computer network that interconnects computers in a limited area such as a home, school, computer laboratory, or office building using network media.

A metropolitan area network (MAN) are high speed networks that connects LAN’s in a metropolitan area. Managed by a consortium of users or a single network provider.

A Wide Area Network (WAN) is a network that covers a broad area i.e. any telecommunications network  that links across metropolitan, regional, or national boundaries.

NETWORK TOPOLOGY

Network topology is the arrangement of the various elements (links, nodes, etc.) of a computer or a biological network. Essentially it is the topological structure of a network and may be depicted physically or logically. Topologies are either: Physical Logical

TYPES OF PHYSICAL TOPOLOGY

Point to Point

Bus Star Ring Mesh Tree Hybrid

POINT TO POINT

Point-to-Point topology is a point-to-point communication channel that appears to the user to be permanently associated with the two endpoints. A tin can telephone is the best example.

BUS

All computers and devices are connected to single cable or BUS. It consists of a main run of cable with a terminator at each end. It is popular on LANs as they are inexpensive and easy to install.

STARIn local area networks with a star topology, each network host is connected to a central hub with a point-to-point connection. In Star topology every node is connected to central node called hub or switch.

RING

A network topology that is set up in a circular fashion in which data travels around the ring in one direction and each device on the right acts as a repeater to keep the signal strong as it travels. Each device incorporates a receiver for the incoming signal and a transmitter to send the data on to the next device in the ring.

MESH

In mesh topology each computer is connected to each other by separate cables. There is a point tom point connection between each node.This type of topology is generally used in military area.

TREE

The type of network topology in which a central 'root' node (the top level of the hierarchy) is connected to one or more other nodes that are one level lower in the hierarchy (i.e., the second level) with a point-to-point link between each of the second level nodes and the top level central 'root' node

HYBRID

Hybrid networks use a combination of any two or more topologies in such a way that the resulting network does not exhibit one of the standard topologies.

ADVANTAGES AND DISADVANTAGES OF THE 4 MOST COMMONLY USED NETWORK TOPOLOGIES

BUS TOPOLOGY

Advantages Easy to connect a computer or peripheral to a linear bus. Requires less cables than any other topologies. Doesn’t requires any specialized network equipment.

Disadvantages Difficult to trouble shoot. Network disruption when more computers are added to

it. A break in the cable will prevent all systems from

accessing the network.

RING TOPOLOGY

Advantages Cable faults are easily located making trouble

shooting easier Ring networks are moderately easily to install.

Disadvantages Expansion to the network can cause network

disruption A single break in the cable can disrupt the entire

network

MESH TOPOLOGY

Advantages Provides redundant path between the devices Network can be expanded without any

inconvenience to current user.

Disadvantages Requires more cables than any other toplology Complicated implementations

STAR TOPOLOGY

ADVANTAGES

DISADVANTAGES

Easy to install and wire. Security can be implemented in the hub/switch. Easy to detect faults and remove parts.

Requires more cable length. If the hub or concentrator fails nodes attached

are disabled More expansive due to he cost of concentrators

associated with it.

NETWORKING DEVICES

Networking devices typically refers to hardware that facilitates the use of a computer network. Computer networking devices are units that mediate data in a computer network. Some of the networking devices are: Gateway Router Switch Bridge Hub Repeater Multiplexer Modem

GATEWAY

A device sitting at a network node for interfacing with another network that uses different protocols.

ROUTER

 A specialized network device that determines the next network point to which it can forward a data packet towards the destination of the packet.

SWITCH

A device that allocates traffic from one network segment to certain lines (intended destinations) which connect the segment to another network segment.

BRIDGE

A device that connects multiple network segments along the data link layer.

HUB

A device  connects multiple Ethernet segments together making them act as a single segment. When using a hub, every attached device shares the same broadcast domain and the same collision domain. Therefore, only one computer connected to the hub is able to transmit at a time.

REPEATER

A device to amplify or regenerate digital signals received while sending them from one part of a network into another.

MULTIPLEXER

A device that combines several electrical signals into a single signal.

MODEM

A device that modulates an analog "carrier" signal (such as sound), to encode digital information, and that also demodulates such a carrier signal to decode the transmitted information, as a computer communicating with another computer over the telephone network.

BROUTER

Brouters are a combination of router and bridge. A Brouter transmits two types of traffic at the exact same time: bridged traffic and routed traffic.

NETWORK INTERFACE CARD

Network Interface Card, or NIC is a hardware card installed in a computer so it can communicate on a network. The network adapter provides one or more ports for the network cable to connect to, and it transmits and receives data onto the network cable.

Network Card

Wireless LAN Card

TRANSCEIVERS

Transceiver short for transmitter-receiver, a device that both transmits and receives analog or digital signals. The term is used most frequently to describe the component in local-area networks that actually applies signals onto the network wire and detects signals passing through the wire. For many LANs, the transceiver is built into the network interface card.

FIREWALL

Firewall is a piece of hardware and/or software which functions in a networked environment to prevent some communications forbidden by the security policy, analogous to the function of firewalls in building construction.

PROXIES

A proxy device acts as a firewall by responding to input packets (connection requests, for example) in the manner of an application, whilst blocking other packets.

A proxy server acts as an intermediary for requests from clients seeking resources from other servers. A client connects to the proxy server, requesting some service, such as a file, connection, web page, or other resource available from a different server and the proxy server evaluates the request as a way to simplify and control their complexity

NETWORKING CABLES

Networking cables are used to connect one network device to other network devices or to connect two or more computers to share a printer, scanner etc. Different types of network cables like Coaxial cable, Optical fibre cable etc.

Coaxial cable

Ethernet

Optical fibre cable