NETWORK TOPOLOGY

PRESENTED BY:- KARAN SINGH

REE032A05 11503083

Introduction to computer network Types of network Introduction to network topology Physical and Logical Topology Types of Topology Advantages and Disadvantages Applications Communication Schemes

Outline:-

Computer Network:-

A computer network is a group of computer systems and other computing hardware devices that are linked together through communication channels to facilitate communication and resource-sharing among a wide range of users. Networks are commonly categorized based on their characteristics.The first computer network designed was the ‘Advanced Research Projects Agency Network (ARPANET)’ by the United States Department of Defense.ARPANET took advantage of the new idea of sending information in small units called packets that could be routed on different paths and reconstructed at their destination.

Local Area Networks (LAN) Personal Area Networks (PAN) Home Area Networks (HAN) Wide Area Networks (WAN) Campus Networks Metropolitan Area Networks

(MAN) Enterprise Private Networks Internetworks Backbone Networks (BBN) Global Area Networks (GAN) The Internet

Types of network:-

Local Area Network (LAN)A Local Area Network (LAN) is a network that is restricted to smaller physical areas e.g. a local office, school, or house. Approximately all current LANs whether wired or wireless are based on Ethernet. Metropolitan Area Network (MAN)A Metropolitan Area Network (MAN) is a network that connects two or more computers, communicating devices or networks in a single network that has geographic area larger than that covered by even a large ‘Local Area Network’ but smaller than the region covered by a ‘Wide Area Network’. MANs are mostly built for cities or towns to provide a high data connection and usually owned by a single large organization. Wide Area Network (WAN)Wide Area Network is a computer network that covers relatively larger geographical area such as a state, province or country.

Network Topology refers to layout of a network and how different nodes in a network are connected to each other and how they communicate. Network Topology is the arrangement of the various elements (links, nodes, etc.) of a computer network. Essentially, it is the topological structure of a network and may be depicted physically or logically.

Network Topology:-

Physical topology is the placement of the various components of a network, including device location and cable installation.while logical topology illustrates how data flows within a network, regardless of its physical design. The actual layout of a network and its media is its Physical Topology.The way in which the data access the medium and transmits packets is the Logical Topology.

Physical and Logical Topology

Bus Topology Ring Topology Star Topology Tree Topology Mesh Topology Hybrid Topology

Types of Topology:-

We will discuss only…

In Bus Topology, all devices are connected sequentially to the same backbone or Transmission line.A signal from the source travels in both directions to all machine connected on the bus cable until it finds the intended recipient. If the machine address does not match the intended address for the data, the machine ignores the data. Alternatively, if the data matches the machine address, the data is accepted.

On the ends of the common cable or bus, a device called a terminator is utilized to absorb signals (electrical energy) and stop the reflections.Terminator is a piece of hardware which prevents signals bouncing back and forth (echoes).

Bus Topology:-

Bus Topology is further divided into two types:1. Linear Bus 2. Distributed Bus.

Linear Bus- All of the nodes of the network are connected to a common transmission medium which has exactly two endpoints.

Distributed Bus- All of the nodes of the network are connected to a common transmission medium which has more than two endpoints.

Most computer motherboard. Ethernet and Local Talk

networks use a linear bus topology

Applications:-

Advantages Inexpensive to install Easy to add stations Use less cable than other

topologies Works well for small networks

Bus Topology

Disadvantages No longer recommended Backbone breaks, whole

network down Limited no of devices can be

attached Difficult to isolate problems Sharing same cable slows

response rates

In Ring Topology, all network devices are connected sequentially to a backbone forming a physical ring.Here the data flow is unidirectional, so when a device sends data, it must travel through each device on the ring until it reaches its destination. In a ring topology, there is no server computer present; all nodes work as a server and repeat the signal.

Ring Topology:-

Ring topologies are found in some office buildings or school campuses.

Token Ring LAN. Token ring local area network (LAN) technology is a communications protocol for local area networks.

Applications:-

Advantages Data packets travel at great

speed No collisions Easier to fault find No terminators required

Ring Topology:-Disadvantages

Requires more cable than a bus

Failure of one computer can impact the rest of the network.

Not as common as the bus – less devices available

Communication schemes are those methods used by various types of local area networks for transferring data from one point to another. Another common term applied to this function is channel access method.

Communication Schemes:-

The term is used especially in networks to describe the situation where two or more nodes attempt to transmit a message across the same wire at the same time.

The contention channel access method involves multiple devices sharing a common transmission media.

This system breaks down when two computers attempt to transmit at the same time. This is a case of collision. To avoid collision, carrier sensing mechanism is used.

Contention:-

Token passing is a channel access method where a signal called a token is passed between nodes that authorizes the node to communicate.

Token passing uses a token, or series of bits, to grant a device permission to transmit over the network. Whichever device has the token can put data into the network. When its transmission is complete, the device passes the token along to the next device in the topology.

Token Passing:-

In a master/slave scenario, the master queries each slave device in turn as to whether it has any data to transmit. If the slave answers yes then the device is permitted to transmit its data. If the slave answers no then the master moves on and polls the next slave device. The process is repeated continuously.

Polling:-