Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28Slide 29Slide 30VLAN: MembershipVLAN ConfigurationVLAN: Communication between switchesVLAN: Advantages15.1Chapter 15Connecting LANs, Backbone Networks, and Virtual LANsCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.15.215-1 CONNECTING DEVICES15-1 CONNECTING DEVICESIn this section, we divide connecting devices into five In this section, we divide connecting devices into five different categories based on the layer in which they different categories based on the layer in which they operate in a network.operate in a network.Passive HubsActive HubsBridgesTwo-Layer SwitchesRoutersThree-Layer SwitchesGatewaysTopics discussed in this section:Topics discussed in this section:15.3Figure 15.1 Five categories of connecting devices15.4Figure 15.2 A repeater connecting two segments of a LAN15.5A repeater connects segments of a LAN.Note15.6A repeater forwards every frame; it has no filtering capability.Note15.7A repeater is a regenerator, not an amplifier.Note15.8Figure 15.3 Function of a repeater15.9Figure 15.4 A hierarchy of hubs15.10A bridge has a table used in filtering decisions.Note15.11Figure 15.5 A bridge connecting two LANs15.12A bridge does not change the physical (MAC) addresses in a frame.Note15.13Figure 15.6 A learning bridge and the process of learning15.14Figure 15.7 Loop problem in a learning bridge15.15Figure 15.8 A system of connected LANs and its graph representation15.16Figure 15.9 Finding the shortest paths and the spanning tree in a system of bridges15.17Figure 15.10 Forwarding and blocking ports after using spanning tree algorithm15.18Figure 15.11 Routers connecting independent LANs and WANs15.1915-2 BACKBONE NETWORKS15-2 BACKBONE NETWORKSA backbone network allows several LANs to be A backbone network allows several LANs to be connected. In a backbone network, no station is connected. In a backbone network, no station is directly connected to the backbone; the stations are directly connected to the backbone; the stations are part of a LAN, and the backbone connects the LANs. part of a LAN, and the backbone connects the LANs. Bus BackboneStar BackboneConnecting Remote LANsTopics discussed in this section:Topics discussed in this section:15.20In a bus backbone, the topology of the backbone is a bus.Note15.21Figure 15.12 Bus backbone15.22In a star backbone, the topology of the backbone is a star;the backbone is just one switch.Note15.23Figure 15.13 Star backbone15.24Figure 15.14 Connecting remote LANs with bridges15.25A point-to-point link acts as a LAN in a remote backbone connected by remote bridges.Note15.2615-3 VIRTUAL LANs15-3 VIRTUAL LANsWe can roughly define a We can roughly define a virtual local area networkvirtual local area network (VLAN) as a local area network configured by (VLAN) as a local area network configured by software, not by physical wiring.software, not by physical wiring.MembershipConfigurationCommunication between SwitchesIEEE StandardAdvantagesTopics discussed in this section:Topics discussed in this section:15.27Figure 15.15 A switch connecting three LANs15.28Figure 15.16 A switch using VLAN software15.29Figure 15.17 Two switches in a backbone using VLAN software15.30VLANs create broadcast domains.NoteVLAN: MembershipPort NumbersMAC AddressIP AddressMulticast IP AddressCombination15.31VLAN ConfigurationManuallyAutomaticSemiautomatic15.32VLAN: Communication between switchesTable maintenanceFrame taggingTime-Division Multiplexing (TDM)15.33VLAN: AdvantagesCost and time reductionCreating Virtual Work