Network - chap 2

Networking

Chapter 2 - Network Topologies

There are two types of network topology. They are,

·         Physical Topology

·         Logical Topology

Physical Topology

The physical topology is the actual layout of the network transmission media .the physical topology defines the way the network looks.

Logical Topology

The logical topology is the logical pathway a signal follows as it passes among the network nodes

Network history and network topologies

                        In present network is most important to all departments. Many departments can’t work even a single day without network. If we dig in to history of network the important of network began to appear in World War 2 time period. Because there were two teams named axis and allies. In that situation there are many secret massages must not read by opposite team. In that case network is needed to their teams in order to send messages secretly. The Networking began to start with development of ARPANET   (Advanced Research Projects Agency Network) .The technical foundation of the internet call Packet Switching and TCP/IP technology was founded by ARPANET. With the foundation of those technologies network became most powerful and implemented frequently. With all this the importance of network topologies appeared in order to share resources. in the beginning ARPANET was a four PC’s network. They communicated each other and shared resources. After that many topologies began to appear in networking. Some of them are Bus topology, Star topology, Ring topology, Mesh topology. These topologies are using to form a network.

Network topologies in detail

                            

Bus Topology

This network is based on a single network cable. sometimes we call as backbone. All nodes are connected linear way. Bus network can connect any other device at any time, so collisions can  occur, MAC address is using to share files to other computers. Although data frames will flow in both directions along the cable, the device which the data is addressed will read it. The cable must be correctly terminated at each end to prevent from problems. The bus topology, security is less, , backbone cables may be used to connect together a number of smaller network segments. The network transmission will flow in linear way

Advantages

·         Easy to implement

·         Best for small networks

·         Easy to find problems

Disadvantages

·         Cable length is limited

·         If the cable breaks wherever the whole network will breakdown

·         Not secure

Ring Topology

Ring Topology Structure is similar to a ring. In other words the cable is connected each computers like a ring. Token ring concept is also included in ring topology. In the ring topology when a computer share files to another computer a ring call token ring will appear .the first computer can share files to next computer via token ring. When sharing files between them other PC’s cant connect to that token ring.

Advantages

·         A central server is not required

·         Data will not misplaced

·         Less cable needed

Disadvantages

·         Whole network fail if one node breakdown

·         Changes will affect network performance

 Star Topology

In a star topology, each device is connected to central node. It can be hub or switch  .the star topology  Has the ability to limit the impact of a single failure.  so that if a component goes down, it only affects that unit's local reach .And also Facilitates adding or removing individual components from a network, for  some reasons. Star Topology structure is shape of a star.

Advantages

• Easy to install
• No disruptions to the network when connecting or removing devices.
• Easy to detect faults

Disadvantages

• Requires more cable length
• If the hub, switch, or concentrator fails, nodes will be down
• More expensive

Mesh Topology

In a mesh topology, each device is connected to several other devices. Reliability High because there are alternative routes to send files for other computers. The main disadvantage is the number of connections required. Mesh topology is connected to other computer via different routes.

Advantages

·         Although a machine breakdown, the whole network wont breakdown

·         Additional devices not affecting to network

·         Can handle high amount of network traffic

Disadvantages

·         Hard to maintain

·         Maintain is expansive

Comparison between Star and Bus topology

Star Topology:-

·         Information’s Share through a central network connection

·         Maintain is expansive than bus topology

·         Secure than bus topology

Bus topology:-

·         Share in a linear way

·         Maintain is cheaper

·         Not secure