Business Data Communications amp Networking Outline Components Architectures Switched Backbone Networks Routed Backbone Networks Virtual LANs VLANs Best Practices Implications for Management ID: 1039003
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1. Chapter 8Backbone NetworksBusiness Data Communications & Networking
2. OutlineComponentsArchitecturesSwitched Backbone NetworksRouted Backbone NetworksVirtual LANs (VLANs)Best PracticesImplications for Management
3. Backbone NetworksHigh-speed network that connects other networks together (LANs, WANs)Distribution layer BNs connect access LANsCore layer BNs connect different buildings
4. Backbone Network ComponentsNetwork cables (often fiber for higher data rates)SwitchesLayer-2 switches are “transparent” devices that do not change messages, only read and forward them (see Ch. 7)Managed switches have configuration options and management featurese.g., spanning tree protocol (STP) or SNMPVLAN switches or layer-3 switches are a devices combine the features of Layer-2 switches and routers, primarily for virtual LANs
5. Backbone Network ComponentsRoutersNetwork layer devices that connect different networksTCP/IP gatewaysNot “transparent” devicesMessages are passed up to the network layer including stripping off data link layer framesRouters respond to ARP (and other messages)Read IP addresses and determine best routeRouting requires more processing than switches
6. Backbone Network LayersSeparate from the layers of the Internet or OSI models, sections of backbone networks are referred to as three different hierarchical layersAccess layer - How users access network (LAN, WLAN)Distribution layer - BN that connects access layer to core layer (within building)Core layer - Connects BNs between buildings and to WAN/Internet
7. Backbone Network ArchitecturesThree major types of BNs are based on the devices usedSwitched backbonesRouted backbonesVirtual LANsIn practice, it is most common to use a combination of these architectures
8. Switched Backbone NetworksMost common type of BN used in the distribution layerUses layer-2 switchesSwitches come in different form factorsDesktopRack-mountedChassisStar topologyPhysical location of devicesMore common to locate centrally in main distribution facility (MDF) or other wiring closets
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10. Switched Backbone NetworksPatch PanelsChassis Switch(4 - 100Base-T ports)Switches(24 port, 100Base-T)Patch CablesBackbone Connection (1000 Base-F)
11. Switched Backbone Networks
12. Switched Backbone Networks
13. Routed Backbone NetworksSometimes called subnetted backbones or hierarchical backbonesTypically used at core layer, but sometimes at distribution layerAdvantagesLAN segmentationDisadvantagesTend to be slowerMore expensiveHarder to manage
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15. Virtual LANs (VLANs)Routers segment networks based on physical location (i.e., the cables connected to it)Devices in different physical locations may need to access to the same LAN resourcesVLANs perform flexible LAN segmentation so that it can based on logical instead of physical designVLANs are enabled by high-speed layer-3 switchesMuch more complex to manage and typically only used in large networks
16. Virtual LANs (VLANs)
17. Virtual LANs (VLANs)Each VLAN identified by VLAN ID which is mapped to traditional IP subnetEach device assigned into a VLAN based on the physical portVLANs are transparentRequire router or Layer-3 switch
18. Virtual LANs (VLANs)Simple single-switch exampleLayer-3 Switch PortsVLAN 10VLAN 2012345678
19. Virtual LANs (VLANs)Multiswitch VLANsL3-switches communicate using inter-switch protocols that support VLANsVLAN trunks are circuits that connect two VLAN switchesVLAN tag inserted into Ethernet frame (e.g., 802.1Q) or encapsulates frame (e.g. ISL)Destination Address(6 bytes)CRC(4 bytes)Preamble & Delimiter(8 bytes)Source Address(6 bytes)Type(2 bytes)Data(46-1500 bytes)802.1Q Header(2 bytes)
20. Virtual LANs (VLANs)
21. Virtual LANs (VLANs)AdvantagesMore flexible subnettingBetter managed traffic flow which may lead to faster performanceTraffic prioritizationCan include quality of service information in tagDisadvantagesComplexMay increase management when VLAN memberships changeLayer 3 switches are more costly than L2
22. Best PracticesArchitectureSwitched has best cost to performance ratio at the distribution layerMost organizations use routed at the core layerVLANs are becoming more widely used, especially for organizations needing the flexibilityTechnologiesGigabit Ethernet for distribution layerGigabit Ethernet or faster for core layerRedundant devices and connections
23. Best Practices
24. Improving Backbone PerformanceDevicesCircuitsDemand
25. Implications for ManagementCost and necessity of upgrading BNs will grow as demand increasesVLAN backbones provide flexibility and are becoming increasingly popularAs with LANs, Ethernet is now the predominant protocol in BNs