Topologies

Networks can be arranged into well-defined structures, known as topologies, that display certain characteristics.

Point to point

Point to point network topology

Point to point networks directly connect two hosts together.

Bus

Bus network topology

Bus networks connect all hosts using T-taps off of a single wire serving as a backbone. All devices receive all messages as a series of +/- 5 volt pulses.

When multiple devices attempt to transmit concurrently, the network interfaces on the hosts identify the 10 volts on the wire and wait a random amount of time before attempting to retransmit, backing off to avoid collisions.

Ring

Ring network topology

In a ring network all of the hosts are connected to a single cable ring. A single token is passed sequentially between all hosts, giving them an opportunity to both read and write data while they hold it.

This model was popular with IBM networks, with a MAU serving as a central hub between all hosts.

Star

Star network topology

This topology is the basis of smaller Ethernet networks, where all hosts are connected to a central hub or switch via point to point connections.

Tree

Tree network topology

Tree networks are comprised of a series of star networks arranged into a hierarchical structure, connected to a linear bus backbone/

Mesh

Mesh network topology

In a mesh network all devices are directly connected, much like a multi-host point to point network. The types of links between hosts vary:

  • Simplex links can only transmit one-way
  • Duplex links are two-way.