Table of Content

Network Physical Topologies

Simple Physical Topologies

Bus Topology Ring Topology Star Topology

Hybrid Physical Topologies Star-wired Ring Topology Star-wired Bus Topology

Network Physical Topologies

After completing this section, students should be able to describe various network topologies, and their attributes.

A topology is the physical layout of the nodes on a network. All networks have a topology, however there exist many different types of topologies. Topologies can be separated into two categories: simple topologies, and hybrid topologies. All of the hybrid topologies are created by mering different simple topologies together.

A network topoloy

Image taken from SmartDraw

Simple Physical Topologies

Simple topologies are the simplest building blocks of any networks. These topologies can be used to create hybrid topologies.

Bus Topology

Bus Topology (Taken from Firewall.cx)

The bus topology is created by connecting all of the network nodes to a single network cable. All nodes on the cable passively listen to the communication on the cable. In this manner, a node on the network broadcast the information that he wants to transfer to an other node. Each of the nodes verify if this information is destined to them.

Since all nodes have access to the information being transferred, this topology is not very secure. An further disadvantage of this topology is its need to share share the available bandwidth between all of its nodes, making this topology ill suited for networks with a large amount of nodes. The biggest advantage of using this topology however is its cheap cost to install.

Ring Topology

Ring Topology (Taken from Firewall.cx)

Ring topology connects all of the nodes with two of their neighbours, forming a closed loop. In this topology each of the nodes listen for data from one of their neighbour, and either keep the data or retransmit the information to the next node. In this manner a token is pasted from one node to the next until it is kept by the destination node, which submits an acknowledgement token to its neighbour for the originator's benefit.

For example, from the diagram, if node 1 wants to send send data node 3 it would perform the following steps:

1. Wait to receive an available token.
2. Add the destination ID (node 3) and the data to the token.
3. Send the token to the next node on the network.
4. The next node (node 2) would verify if the destination node for the token is it self. Since it is destined for node 3, node 2 would replicate the token to the next node.
5. The next node (node 3) would verify if the destination node for the token is it self. Since this is the destination, node 3 would read the information, and send an acknowledgement token for node 1 to the next node (node 4).
6. The next node (node 4) would verify if the destination node for the token is it self. Since it is destined for node 1, node 4 would replicate the token to the next node.
7. The next node (node 1) would verify if the destination node for the token is it self. Since this is the destination, node 1 would know that the data had been properly delivered.
8. Node 1 would then release an empty token to the next node, this would allow an other node on the network to send data by repeating step 1.

Star Topology

Star Topology (Taken from Firewall.cx)

All nodes in a star topology are connected to a central device. The central device is most often a hub or a switch, which

By isolating each of the nodes, star topology are more fault-tolerant than bus and ring topologies. However, this topology does require more cabling then the other topologies, and they are typically harder to configure. This topology is also the most scalable of the topologies presented here.

Hybrid Physical Topologies

Hybrid topologies are the networks which are created by connecting more then one simple topology network together. That is, hybrid topologies are always made up of two or more physical topologies.

Star-wired Ring Topology

Hybrid-Star Topology (Taken from Firewall.cx)

The star ring topology consist of two or more star topology network which are interconnected with each other with a token ring topology network. In these network, the central device in each of the star networks acts as a node in the ring system.

Star-wired Bus Topology

Hybrid-Star Topology (Taken from Firewall.cx)

The star bus topology consist of two or more star topology network which are interconnected with each other with a bus topology network. In these network, the central device in each of the star networks acts as a node in the bus system.