A Bus topology is a network topology in which all nodes connect to the network via a central cable, , called the bus. The bus acts as the shared communication medium that the devices are attached to. Any device that wants to communicate with other device on the network will send its data over the bus which will be send to all attached devices but the intended recipient will only process that packet. Thus bus topology is good and easy to setup for only a small number of devices, as devices and network utilization increases the performance issues and problems arise. If the bus is damaged then the whole network fails making bus topology a less preferred option.

Figure below shows the bus topology architecture



In a Ring topology every device/node is connected to exactly two other nodes one on either side of it in closed loop fashion. All messages travel though the ring either in a clockwise direction or anti-clockwise direction. Ring topology is very rarely used today because they are expensive, difficult to install and manage. A failure in any single connection disrupts the ring topology thus also making ring topology a rare choice for network topologies.

Figure below shows the ring topology architecture



Star topology is the most common topology and is the widely implemented. In a Star Topology every device is connected to a central device such as a switch. Star topology requires more cable as compared to other topologies but it mode robust as a failure in one cable will only disconnect the specific connected computer via that cable to the central device. The messages between systems will always flow via the central device and so if the central device fails the entire network will fail. Star topology is very easy install, manage and troubleshoot making it the most common topology in home and office networks.

Figure below shows the star topology architecture



In a Mesh topology nodes are connected to each other in a redundant fashion with multiple connections. There are two types of mesh topologies, Partial and Full. In a full mesh topology all devices are connected to each other which is very expensive but provides the best redundancy as a failure of a single does not affect the network connectivity. In partial mesh devices partially connect with each other some devices have connectivity with some devices while others have different peers. There are several different paths available in mesh topology and nodes are intelligent devices like routes which can route packets on different algorithms such as Shortest Path First algorithm. The Internet is an example of partial mesh architecture

Figure below shows the mesh (Partial) topology architecture.



Today we covered a basic yet important lesson on network topologies. As we move ahead in Cisco CCNA certification learning we will see more lessons and technologies that require a firm understanding of this lesson. For instance today’s Ethernet LANs are implemented using the star topology architecture while the Wide Area Networks are implemented in mesh fashion using routers.