Basic objective of this lecture is to describe on Hubs and Switches according to Router. Hubs indicates only one transmission at a time. Transmission from a station received by central hub and re transmitted on all outgoing lines. Layer 2 Switches are: Flat address space, Broadcast storm and only one path between any 2 devices. Routers connect to several networks, including backbone networks of inter-connected routers. These networks may be of different (data link) types like; Ethernet, Token Ring, FDDI etc.