1. Network Topology • Network topology is the layout pattern of interconnections of various elements of a computer network. • Four Main Topologies • Point-to-point • Bus • Star • Tree

2. Point-to-Point Topology • This is the simplest topology and it is a permanent link between two endpoints. • Two subcategories: • permanent topology, this is a point-to-point communication channel that appears, to the user, to be permanently associated with the two endpoints. • switched topology, this uses circuit-switching technologies, a point-to-point circuit can be set up dynamically, and dropped when no longer needed.

3. Bus Topology • each node is connected to a single cable. • Two subcategories: • linear bus, this network topology in which all of the nods of the network are connected to a common transmission medium, which has two end point. • is distributed bus topology is a topology in which all nodes in the network are connected to a common transmission medium which has more than endpoints that are made by adding branches to the main section.

4. Star Topology • each network host is connected to a central hub. In contrast to the bus topology, the star topology connects each node to the hub with a point-to-point connection.

5. Tree Topology • This topology has a central root node that is connected to one or more other nodes that are one level lower in the network. It has a point-to-point link between the second and top level central nodes. A the same time, the second level nodes that are connected to the top will also have nodes connected to it that is one level lower.