What Are Network Topologies?

Updated March 15, 2017 / Posted May 05, 2011

By Vangie Beal

Network Topology refers to layout of a network. How different nodes in a network are connected to each

other and how they communicate is determined by the network's topology.

Network Topology refers to the layout of a network and how different nodes in a network are

connected to each other and how they communicate. Topologies are either physical (the physical layout of

devices on a network) or logical (the way that the signals act on the network media, or the way that the data

passes through the network from one device to the next). This Webopedia Study Guide describes five of the most
common network topologies.

Network Topology Checklist

Key Terms to Know

Mesh Topology

Star Topology

Bus Topology

Ring Topology

Tree Topology

Getting Started: Key Terms to Know

The following definitions will help you to better understand network topology:
 Network
 Topology
 Node
 Physical Topology
 Logical Topology
1. Mesh Topology
Mesh Topology: In a mesh network, devices are connected with many redundant interconnections between

network nodes. In a true mesh topology every node has a connection to every other node in the network. There

are two types of mesh topologies:

 Full mesh topology: occurs when every node has a circuit connecting it to every other

node in a network. Full mesh is very expensive to implement but yields the greatest amount of redundancy, so in

the event that one of those nodes fails, network traffic can be directed to any of the other nodes. Full mesh is

usually reserved for backbone networks.

Partial mesh topology: is less expensive to implement and yields less redundancy than full mesh topology. With

partial mesh, some nodes are organized in a full mesh scheme but others are only connected to one or two in the

network. Partial mesh topology is commonly found in peripheral networks connected to a full meshed backbone.
2. Star Topology
Star Topology: In a star network devices are connected to a central computer, called a hub. Nodes communicate

across the network by passing data through the hub.

Main Advantage: In a star network, one malfunctioning node doesn't affect the rest of the network.

Main Disadvantage: If the central computer fails, the entire network becomes unusable.
3. Bus Topology
Bus Topology: In networking a bus is the central cable -- the main wire -- that connects all devices on a local-area

network (LAN). It is also called the backbone. This is often used to describe the main network connections

composing the Internet. Bus networks are relatively inexpensive and easy to install for small

networks. Ethernetsystems use a bus topology.

Main Advantage: It's easy to connect a computer or device and typically it requires less cable than a star

topology.
Main Disadvantage: The entire network shuts down if there is a break in the main wire and it can be difficult to

identify the problem if the network shuts down.

4. Ring Topology
Ring Topology: A local-area network (LAN) whose topology is a ring. That is, all of the nodes are connected in a

closed loop. Messages travel around the ring, with each node reading those messages addressed to it.
Main Advantage: One main advantage to a ring network is that it can span larger distances than other types of

networks, such as bus networks, because each node regenerates messages as they pass through it.

5. Tree Topology
Tree Topology: This is a "hybrid" topology that combines characteristics of linear bus and star topologies. In a

tree network, groups of star-configured networks are connected to a linear bus backbone cable.

Main Advantage: A Tree topology is a good choice for large computer networks as the tree topology "divides"

the whole network into parts that are more easily manageable.
Main Disadvantage: The entire network depends on a central hub and a failure of the central hub can cripple the

whole network.

https://www.webopedia.com/quick_ref/topologies.asp

Types of Network Topology

Network Topology is the schematic description of a network arrangement, connecting
various nodes(sender and receiver) through lines of connection.

BUS Topology
Bus topology is a network type in which every computer and network device is
connected to single cable. When it has exactly two endpoints, then it is called Linear
Bus topology.
Features of Bus Topology

1. It transmits data only in one direction.

2. Every device is connected to a single cable

Advantages of Bus Topology

1. It is cost effective.
2. Cable required is least compared to other network topology.
3. Used in small networks.
4. It is easy to understand.
5. Easy to expand joining two cables together.

Disadvantages of Bus Topology

1. Cables fails then whole network fails.

2. If network traffic is heavy or nodes are more the performance of the network
decreases.
3. Cable has a limited length.
4. It is slower than the ring topology.

RING Topology
It is called ring topology because it forms a ring as each computer is connected to
another computer, with the last one connected to the first. Exactly two neighbours for
each device.
Features of Ring Topology

1. A number of repeaters are used for Ring topology with large number of nodes,
because if someone wants to send some data to the last node in the ring topology
with 100 nodes, then the data will have to pass through 99 nodes to reach the 100th
node. Hence to prevent data loss repeaters are used in the network.
2. The transmission is unidirectional, but it can be made bidirectional by having 2
connections between each Network Node, it is called Dual Ring Topology.
3. In Dual Ring Topology, two ring networks are formed, and data flow is in opposite
direction in them. Also, if one ring fails, the second ring can act as a backup, to keep
the network up.
4. Data is transferred in a sequential manner that is bit by bit. Data transmitted, has to
pass through each node of the network, till the destination node.

Advantages of Ring Topology

1. Transmitting network is not affected by high traffic or by adding more nodes, as only
the nodes having tokens can transmit data.
2. Cheap to install and expand
Disadvantages of Ring Topology

1. Troubleshooting is difficult in ring topology.

2. Adding or deleting the computers disturbs the network activity.
3. Failure of one computer disturbs the whole network.

STAR Topology
In this type of topology all the computers are connected to a single hub through a cable.
This hub is the central node and all others nodes are connected to the central node.

Features of Star Topology

1. Every node has its own dedicated connection to the hub.

2. Hub acts as a repeater for data flow.
3. Can be used with twisted pair, Optical Fibre or coaxial cable.

Advantages of Star Topology

1. Fast performance with few nodes and low network traffic.

2. Hub can be upgraded easily.
3. Easy to troubleshoot.
4. Easy to setup and modify.
5. Only that node is affected which has failed, rest of the nodes can work smoothly.

Disadvantages of Star Topology

1. Cost of installation is high.

2. Expensive to use.
3. If the hub fails then the whole network is stopped because all the nodes depend on
the hub.
4. Performance is based on the hub that is it depends on its capacity

MESH Topology
It is a point-to-point connection to other nodes or devices. All the network nodes are
connected to each other. Mesh has n(n-1)/2 physical channels to link n devices.
There are two techniques to transmit data over the Mesh topology, they are :

1. Routing
2. Flooding

MESH Topology: Routing

In routing, the nodes have a routing logic, as per the network requirements. Like routing
logic to direct the data to reach the destination using the shortest distance. Or, routing
logic which has information about the broken links, and it avoids those node etc. We can
even have routing logic, to re-configure the failed nodes.

MESH Topology: Flooding

In flooding, the same data is transmitted to all the network nodes, hence no routing logic
is required. The network is robust, and the its very unlikely to lose the data. But it leads
to unwanted load over the network.
Types of Mesh Topology

1. Partial Mesh Topology : In this topology some of the systems are connected in the
same fashion as mesh topology but some devices are only connected to two or three
devices.
2. Full Mesh Topology : Each and every nodes or devices are connected to each
other.

Features of Mesh Topology

1. Fully connected.
2. Robust.
3. Not flexible.

Advantages of Mesh Topology

1. Each connection can carry its own data load.

2. It is robust.
3. Fault is diagnosed easily.
4. Provides security and privacy.
Disadvantages of Mesh Topology

1. Installation and configuration is difficult.

2. Cabling cost is more.
3. Bulk wiring is required.

TREE Topology
It has a root node and all other nodes are connected to it forming a hierarchy. It is also
called hierarchical topology. It should at least have three levels to the hierarchy.

Features of Tree Topology

1. Ideal if workstations are located in groups.

2. Used in Wide Area Network.

Advantages of Tree Topology

1. Extension of bus and star topologies.

2. Expansion of nodes is possible and easy.
3. Easily managed and maintained.
4. Error detection is easily done.

Disadvantages of Tree Topology

1. Heavily cabled.
2. Costly.
3. If more nodes are added maintenance is difficult.
4. Central hub fails, network fails.

HYBRID Topology
It is two different types of topologies which is a mixture of two or more topologies. For
example if in an office in one department ring topology is used and in another star
topology is used, connecting these topologies will result in Hybrid Topology (ring
topology and star topology).
Features of Hybrid Topology

1. It is a combination of two or topologies

2. Inherits the advantages and disadvantages of the topologies included

Advantages of Hybrid Topology

1. Reliable as Error detecting and trouble shooting is easy.

2. Effective.
3. Scalable as size can be increased easily.
4. Flexible.

Disadvantages of Hybrid Topology

1. Complex in design.
2. Costly.

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