LAN topologies: Network topology is a physical schematic that demonstrates interconnection of the many users. There are four fundamental topologies as under:

(i) Direct Connection or one to all topology

(ii) Star topology

(iii) Ring topology

Direct connection or one to one topology:In the one to all topology, there is a path between every node and every other node. Number of paths required is defined by equation  P  =  (n²-n)/2,  where  n  is  number  of  nodes  and  P,  total number  of  paths.  Hence number  of  paths  increases  significantly  as  the  number  of nodes  increases.  Every node  should be  physically  able  to  connect  to  paths  to  every other  node  so  a  very  large  connector  and associated interface  support circuitry is needed at every node. Adding a new node requires major rewiring and affects the software which manages communications for the system.