In this section, we divide connecting devices into five different categories based on the layer in which they operate in a network. | Chapter 15 Connecting LANs, Backbone Networks, and Virtual LANs Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15. 15-1 CONNECTING DEVICES In this section, we divide connecting devices into five different categories based on the layer in which they operate in a network. Passive Hubs Active Hubs Bridges Two-Layer Switches Routers Three-Layer Switches Gateways Topics discussed in this section: 15. Figure Five categories of connecting devices 15. Figure A repeater connecting two segments of a LAN 15. A repeater connects segments of a LAN. Note 15. A repeater forwards every frame; it has no filtering capability. Note 15. A repeater is a regenerator, not an amplifier. Note 15. Figure Function of a repeater 15. Figure A hierarchy of hubs 15. A bridge has a table used in filtering decisions. Note 15. Figure A bridge connecting two LANs 15. A bridge does not change the physical (MAC) addresses in a frame. Note 15. Figure A learning bridge and the process of learning 15. Figure Loop problem in a learning bridge 15. Figure A system of connected LANs and its graph representation 15. Figure Finding the shortest paths and the spanning tree in a system of bridges 15. Figure Forwarding and blocking ports after using spanning tree algorithm 15. Figure Routers connecting independent LANs and WANs 15. 15-2 BACKBONE NETWORKS A backbone network allows several LANs to be connected. In a backbone network, no station is directly connected to the backbone; the stations are part of a LAN, and the backbone connects the LANs. Bus Backbone Star Backbone Connecting Remote LANs Topics discussed in this section: 15. In a bus backbone, the topology of the backbone is a bus. Note 15. Figure Bus backbone 15. In a star backbone, the topology of the backbone is a star; the backbone is just one switch. Note 15. Figure Star backbone 15. Figure Connecting remote LANs with bridges 15. A point-to-point link acts as a LAN in a remote backbone connected by remote bridges. Note 15. 15-3 VIRTUAL LANs We can roughly define a virtual local area network (VLAN) as a local area network configured by software, not by physical wiring. Membership Configuration Communication between Switches IEEE Standard Advantages Topics discussed in this section: 15. Figure A switch connecting three LANs 15. Figure A switch using VLAN software 15. Figure Two switches in a backbone using VLAN software 15. VLANs create broadcast domains. Note 15. | Chapter 15 Connecting LANs, Backbone Networks, and Virtual LANs Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 15. 15-1 CONNECTING DEVICES In this section, we divide connecting devices into five different categories based on the layer in which they operate in a network. Passive Hubs Active Hubs Bridges Two-Layer Switches Routers Three-Layer Switches Gateways Topics discussed in this section: 15. Figure Five categories of connecting devices 15. Figure A repeater connecting two segments of a LAN 15. A repeater connects segments of a LAN. Note 15. A repeater forwards every frame; it has no filtering capability. Note 15. A repeater is a regenerator, not an amplifier. Note 15. Figure Function of a repeater 15. Figure A hierarchy of hubs 15. A bridge has a table used in filtering decisions. Note 15. Figure A bridge connecting two LANs 15. A bridge does not change the .
