Network Topology

                                   Network topologies

The topology of a network is the logical structure of the connections
in a network. Here are three topologies you might encounter.

Star topology

When we talked about designing and wiring networks, we assumed that
we were working with an Ethernet switch or hub in the middle. The
topology or shape of this network is called a star. A star is called that
because all the network clients talk to the hub or switch in the middle.
 

 

 

 

 

 

 

 

Bus Topology

Another topology is the bus. An Ethernet network using coax uses a
bus topology. All the network nodes are connected to a shared cable,
so there is no central device. Each node on the network deals with
all the traffic.

 

Token Ring Topology

A third topology is the ring. Token Ring is the most widely used ring
technology. It was designed by IBM and is a proprietary technology,
so it wasn’t as widely adopted as Ethernet. Token Ring uses a “token”
packet that is sent from client to client. The client holding the token is
allowed to send network traffic.

Mesh Topology

 A mesh network uses a network topology in which each node (called a mesh node) relays data for the network. All nodes cooperate in the distribution of data in the network.

Designers of mesh networks can employ a flooding technique or a routing technique. When using a routing technique, the message is propagated along a path, by hopping from node to node until the destination is reached. To ensure all its paths' availability, a routing network must allow for continuous connections and reconfiguration around broken or blocked paths, using self-healing algorithms. Self-healing capability enables a routing-based network to operate when one node breaks down or when a connection becomes unreliable. As a result, the network is typically quite reliable, as there is often more than one path between a source and a destination in the network. Although mostly used in wireless situations, this concept can also apply to wired networks and to software interaction.

A mesh network whose nodes are all connected to each other is a fully connected network. Fully connected wired networks have the advantages of security and reliability: problems in a cable affect only the two nodes attached to it. However, in such networks, the number of cables, and therefore the cost, goes up rapidly as the number of nodes increases.