Multiple Hubs can be used to extend the network length For 10BaseT and 100BaseT the maximum length of the connection between an adapter and the hub is 100 meters the maximum length between any two nodes is 200 m = maximum network length Broadcast domain: is that part of the network (set of NIC) where each NIC can 'see' other NICs' traffic broadcast messages. McGraw-Hill The McGraw-Hill Companies, Inc., 2004 Hubs The entire hub forms a single collision domain, and a single Broadcast domain Collision domain: is that part of the network (set of NICs) when two or more nodes transmit at the same time collision will happen. does not do filtering (forward a frame into a specific destination or drop it) just it copy the received frame onto all other links Hub receives a bit from an adapter and sends it to all the other adapters without implementing any access method. McGraw-Hill The McGraw-Hill Companies, Inc., 2004 Hubs Acts on the physical layer Operate on bits rather than frames Also called multiport repeater Used to connect stations adapters in a physical star topology but logically bus Connection to the hub consists of two pairs of twisted pair wire one for transmission and the other for receiving. McGraw-Hill The McGraw-Hill Companies, Inc., 2004 Figure 3 A repeater connecting two segments of a LAN McGraw-Hill The McGraw-Hill Companies, Inc., 2004 Figure 2 Function of a repeater McGraw-Hill The McGraw-Hill Companies, Inc., 2004 Repeaters Repeaters do not implement any access method If any two nodes on any two connected segments transmit at the same time collision will happen segment length 185m - 4 repeaters (5 segments) are used to extend the cable to 925m segment length 500m 4 repeaters (5 segments) are used to extend the cable to 2500m) Ethernet 10Base2- Max. McGraw-Hill The McGraw-Hill Companies, Inc., 2004 Repeaters A physical layer device the acts on bits not on frames or packets Can have two or more interfaces When a bit (0,1) arrives, the repeater receives it and regenerates it, the transmits it onto all other interfaces Used in LAN to connect cable segments and extend the maximum cable length extending the geographical LAN range Ethernet 10base5 Max. McGraw-Hill The McGraw-Hill Companies, Inc., 2004 Figure 1 Five categories of connecting devices McGraw-Hill The McGraw-Hill Companies, Inc., 2004 Internetworking devices Repeaters Hubs Bridges Switches Routers Gateway
McGraw-Hill The McGraw-Hill Companies, Inc., 2004 Connecting LANs and Backbone Networks