中樞神經(jīng)系統(tǒng)結(jié)構(gòu)設(shè)計(jì),骨干ppt課件

1、1Outline1. Enterprise Backbone Basics2. Structured Cabling3. Types of Backbones4. Backbone Examples 5. The Network Development Life Cycle (NDLC)2Enterprise Backbone BasicslModern organizations havelLarge networkslComplex communication requirementslAccess to mainframe datalInternetworking of several

2、LANslConnectivity to a WAN (the Internet)lTransmission of data and non-data3Backbone Basics (Cont.)lComplex requirements mandated the structuring of enterprise-wide information distribution.lSuch structuring is effectively achieved through a system called Backbone.lStructured wiring combined with Ba

3、ckbone solution provide a powerful and efficient networking solution to company-wide communication needs.4Backbone Basics (Cont.)lKey Factors in assessing network topologies:lPerformancelHighest network availability.lLowest latency.lMost appropriate connectivity for users.lScalabilitylAbility to exp

4、and the network in terms of end-points and aggregate bandwidth without affecting existing users.5Backbone Basics (Cont.) Cost of administration: The inherent ease of moves, adds, and changes, plus the capability to efficiently diagnose, remedy, or prevent network outages. Structured Backbone solutio

5、ns offer Flexibility Scalability Troubleshooting & Manageability Performance6Structured CablinglCabling plan should be easy to:limplement, andlaccommodates future growth.lTwo standards have been issued that specify cabling types and layout for structured commercial buildings wiring.lA network sh

6、ould follow a cabling plan:lSelection of cable typeslCable layout topology7Structured Cabling StandardslEIA/TIA-568: Issued jointly by the Electronic Industries Association and the Telecommunications Industry Assoc.lISO 11801: Issued by the International Organization for Standardization.lBoth Standa

7、rds are similar.8Structured Cabling (Cont.)lIt is a generic wiring scheme with the following characteristics:lWiring within a commercial building.lCabling to support all forms of information transfer.lCable selection and layout is independent of vendor and end-user equipment.lCable layout designed t

8、o encompass distribution to all work areas within the building (relocation wouldnt need rewiring).9Structured Cabling (Cont.)lBased on the use of a hierarchical star-wired cable layout.lExternal cables terminate at Equipment Room (ER).lPatch panel and cross-connect hardware connect ER to Internal Di

9、stribution Cable.lTypically, first level of distribution consists of Backbone cables.lBackbone cable(s) run from ER to Telecom Closets (Wiring Closets) on each floor.10Structured Cabling (Cont.) Wiring Closet contains cross-connect equipment for interconnecting cable on a single floor to the Backbon

10、e. Cable distributed on a single floor is called Horizontal Cabling, and connects the Backbone to Wall Outlets that service individual telephone and data equipment.11Structured Cabling (Cont.)lBased on the use of a hierarchical star-wired cable layout.ExternalCableTelecom.ClosetEquipmentRoomBackbone

11、HorizontalCableWorkArea12Structured Cabling TerminologyBackboneA facility between telecommunications closets or floor distribution terminals, the entrance facilities, and the equipment rooms within or between buildingsHorizontal CablingThe wiring/cabling between the telecomoutlet and the horizontal

12、cross-connect13Terminology (Cont.)Cross-ConnectA facility enabling the termination of cable elements & their interconnection, and/or cross-connection, primarily by means of a patch cord or jumperEquipment RoomA centralized space for telecom equipt that serves the occupants of the building (Bldg/

13、Campus distributor in ISO 11801)14Terminology (Cont.)Telecommunications Closet:An enclosed space for housing telecom eqpt, cable terminations, and cross-connect cabling; the location for cross-connection between the backbone and horizontal facilitiesWork AreaA building space where the occupants inte

14、ract with the telecom terminal eqpt15Terminology (Cont.)Main Cross-ConnectA cross-connect between 1st and 2nd level backbone cables, entrance cables, and equipment cables (no ISO name)Intermediate Cross-ConnectA cross-connect between 1st and 2nd level backbone cabling (no ISO name)16Terminology (Con

15、t.)Horizontal Cross-Connect:A cross-connect of horizontal cabling to other cabling, e.g. horizontal, backbone, or equipment (no ISO name)Telecommunications OutletA connecting device in the work area on which horizontal cable terminates17Media RecommendedTelecomm.OutletHorizontalCross-connectMainCros

16、sconnectIntermediateCross-connectTelecomm.OutletHorizontalCross-connectACBDD18Cable DistanceslUTP (Voice Transmission) lMC-HC HC-ICMC-ICTO-HClA BC Dl 800m500m 300m90mlCat 3 or 5 UTP (up-to 16 or 100 MHz), land STP (up-to 300 MHz)lA BC Dl 90m90m 90m90m19Cable Distances (Cont.)l62.5 microns FiberlMC-H

17、C HC-ICMC-ICTO -HClA BC Dl 2000m500m 1500m90mlSingle-Mode FiberlA BC Dl3000m500m 2500m90m20Unstructured Backbone - MainframeTerminalsMainframe.Cluttered and noisycable risers.21Unstructured Backbone - LANEach station must be physically connected by a thick coax tapped to the LAN coax, running by all

18、 stations.22Structured BackbonelBy using a MUX or similar device, a backbone can be structured.lA single fiber pair replaces mounds of coax cable, andlfloor-to-floor traffic is systematically organized.lWith Structure comes enhancedlnetwork controllreliability, andlefficiency.23Structured Backbone (

19、Cont.)lStructured backbone = structured, hierarchical physical star wiring scheme.MainframeMUXMUXMUX24Structured Backbone(Cont.)lThe first information backbone emerged in the mid 1980s.lAn enterprise backbone is an aggregate data path (a central communication highway) for the transport of all signal

20、s to / from users distributed throughout the enterprise.lEarly backbones were mainly muxes.25Structured Backbone(Cont.)lThe enterprise network is usually comprised of three main parts:lThe horizontal access portion:lConnecting individual workstations to wiringlclosets and most often accomplished via

21、 anlintelligent cabling Hub.lThe Backbone portion:lFacilitating floor-to-floor or building-to-buildinglconnectivity.26Structured Backbone (Cont.) The Wide Area Network linkHorizontalaccessBackboneWANInterface27When are Backbones needed?lCompanies utilizing Backbone techno-logy have typically one or

22、more of the following communication needs:lMultiple data protocols and signals.lHeavy network traffic to be supported simultaneously.lMultiple workgroups, networks, and facilities that need to be internetworked.lMission critical applications where high reliability and security are mandatory.28When a

23、re Backbones needed? (Cont.) Need to support varying media and device types. A high degree of upgradeability, so that existing equipment can be preserved and higher performance hardware and software solutions can be implemented seamlessly. A high degree of network moves, adds, and changes, requiring

24、 that the enterprise network be highly manageable.29Types of (private) BackbonesThree broad categories:(1) Multiplexers-based.(2) LAN Backbones.FDDI, Ethernet, Token Ring, etc(3) Collapsed Backbones.High-speed Router, ATM. 30Public BackbonesPublic telephone/data network31Backbone TopologieslStarlCol

25、lapsed BackbonelPBX systemlSwitch-based networks32Backbone Topologies (Cont.)lRing. lEx: FDDI.33Backbone Topologies (Cont.)lHierarchical/Inverse Tree.lHigher power at higher levels.34Backbone Topologies (Cont.)lMesh.lMultiple data paths between peer stations.lTopology relies on the use of Routers.35

26、Backbone Benefits+ Makes complex distributed computing environment easier to manage.+ Allows Organizations to easily upgrade the system.+ Creates an integrated communication path capable of accommodating the enterprises data transfer requirements safely and cost effectively.36Fiber OpticslMany of th

27、e Backbone advantages are enabled by the implementation of fiber.lAdvantages of fiber:l+ Ability to combine data, voice & video signals over a single fiber pair.l+ Very large bandwidth: (allows large number of users, is cost effective and space-conservative).l+ Increased data security & reli

28、ability.37Application / BandwidthlHigh capacity Backbone is a must to support increasing need for bandwidth.l ApplicationBandwidthl Digital audio1.4 Mbpsl Compressed video (JPEG)2 - 10 Mbpsl Document Reprographics20 -100 Mbpsl Compressed broadcast-quality TV20 -100 Mbpsl High-definition full motion

29、video1 - 2 Gbpsl Chest X-Ray4 - 40 Mbpsl Remote query burst1 Mbps38Multiplexer-Based BackboneslThe first Backbones were Mux-based.lDesigned for and continued to be used predominantly in the mainframe environment.lSuitable for situations when a mixture of LAN and host-to-terminal traffic needs to be

30、supported via a common Backbone.lA Mux is a device that simultaneously transmits several messages or signals across a single channel or data path.39Multiplexer-Based BackboneslTwo primary types of Backbone Muxes in use today:lTime Division Mux (TDM).lStatistical or Stat Mux.40Time Division MuxeslA T

31、DM combines signals onto a high speed link, and then sends those signals sequentially at fixed time intervals.lEach user interface is allocated a time slot within which its data is transmitted.lData is usually sent one char at a timelCombined signal rates 100 Mbps.41Time Division MuxesEthernetToken

32、RingMainframeEthernetToken RingMainframeMTEMTEMTEMTE.Aggregate pathwayMuxingDe-Muxing42TDM Strengths+ Dedicated bandwidth partitions= Guaranteed throughput & no loss.+ Versatile & scaleable.+ Low cost compared to Stat. TDM.+ Proven Reliable data transport.43TDM Weaknesses- Bandwidth of idle

33、sources is lost.- Minimal internetworking capability. 44Statistical TDMlBased on the premise that stations rarely need to transmit data constantly at full available speed.lAttempts to move as much data as possible across the common channel.lCombined bandwidth of all sources exceeds the available ban

34、dwidth.lAllocates time slots on-demand, constantly evaluating traffic needing to be sent (based on priority). 45Stat-Mux (Cont.)lIn case demand exceeds capacity, lower-priority traffic is off-loaded into a buffer and delayed for retransmission during a non-peak period l=More complex front-end manage

35、ment.lGreater degree of intelligence.lGreater computer power.46Stat-Mux Strengths+ Supports more data than available bandwidth= better bandwidth utilization.+ Critical data can be given higher priority.47Stat-Mux Weaknesses- Requires more management and more expensive to operate.- Low priority data

36、can suffer excessive delays.- Data may get lost. (No guaranteed bandwidth)48Emerging Backbone TechnologieslThree of the most promising Backbone technologies are:lAsynchronous Transfer Mode (ATM).lSynchronous Optical Network (SONET).lFibre Channel.49ATMlTodays collapsed Backbones are based on Router

37、technology.lTomorrows collapsed Backbones will be based on switching technology.lATM is predicted to be at the core of the switching technology.lATM is hailed as the first solution that will erase the barriers between LANs and WANs.50ATM (Cont.)ATMATMServerWANInterfaceRouterBackbone51ATM Benefits+ C

38、ombines best features of Muxes and LAN Backbones.+ ATM rides on top of a highly scaleable physical layer protocol such as Fiber channel and SONET.+ Short & fixed-length cells = Relatively low cost hardware implementation.+ Can accommodate both real-time and non-real-time data.52ATM Benefits (Con

39、t.)+ Provides high throughput.+ ATM is not protocol-dependent. Any packet format can be mapped into ATM cells and transported.= It is an ideal data transfer system for changing LAN environments.53How ATM Works?lData Units: Fixed-length cells of size 53 bytes each (5 Header + 48 payload).lOperates at

40、 the equivalent of MAC sublayer. Operates above physical layer which could be SONET, Fibre channel,.lConnection-oriented.lUniversal transfer mode for all B-ISDN services.lLayered architecture. 54ATM Layered ArchitectureHigher LayersUser Services & applicationsATM Adaptation LayerATM LayerPhysica

41、l MediumDependent LayerFragmentation andde-fragmentation of framesCell header insertion/removalCell relaying & multiplexingConnection establishmentTransmission & receipt of bitsSynchronization55How ATM Works?Data packetAALATMPhysical Layer56How ATM Works (Cont.)?Physical LayerATMEntire proce

42、ss is reversedOverheadEnvelopeCell57Examples of ATM SwitcheslFORE SystemslASX-200BX (2.5 Gbps backplane)lASX-1000 (10 Gbps backplane)lCISCO SystemslNWAYS 8260 (5 Gbps backplane)lBay NetworkslCentillian-100: campus ATM switchl(3.2 Gbps backplane)58Examples of ATM Switches (Cont.)lIBM lNWAYS 8260 (5 G

43、bps backplane)lMADGE NetworkslCollage 740: Campus ATM switchl(5 Gbps backplane)lALCATELl1100 LSS Series 550A59Synchronous Optical NetworkSONET is ANSI & ITU Standard.First standard optical interface.Used in the public network and is being adopted as a private Backbone solution.American SONET Sta

44、ndard:Rates start at OC-1:51.84 MbpsScaling up to OC-48: 2.48 Gbps60SONET (Cont.)lEuropean SDH:lInitial Rate: SDH-1 = OC-3: 155.52 MbpslSONET provides a transport payload envelope and framing format. Any type of data is transparently transmitted with low delays.lSONET is currently defined for use wi

45、th single mode fiber.61Fibre ChannellANSI X3T9.3 Standard.lDeveloped as high speed interface for linking mainframes and their peripherals.lBetter suited as a private Backbone becauselless overheadllowest implementationlmulti-mode fiber62Fibre Channel (Cont.)Is also highly expandableInitial Rate: 100

46、 MbpsScales up to: 1.6 GbpsHas a transport payload envelope63LAN BackboneslUnlike Muxes which are capable of transmitting an array of data, host-to-host, voice and video signals, LAN Backbones are dedicated exclusively for LAN communication.lActually, any legacy LAN such as Ethernet or Token Ring ca

47、n be called a backbonelLANs constitute the primary datapaths.64LAN Backbones (Cont.)lIn the broader context of Backbones, the key LAN standard that has far-reaching Backbone-based applications is the Fiber Distributed Data Interface (FDDI).lFDDI is (still?) the dominant LAN Backbone in use. It provi

48、des standards-based connectivity for legacy LANs (Ethernet & Token Ring).65LAN Backbones (Cont.)Token RingEthernetToken RingEthernetEthernetToken RingAll of the protocols areconverted to the FDDI transport protocolData is Bridged/Routed from the high-speed Backbone to destination LAN66LAN Backbo

49、nes (Cont.)lFDDI complements existing LANs by providing a high-speed path upon which all LAN protocols can be transported.lTypical FDDI applications:lBackbone connectivity between LANs in a building or campus.lLAN for high-end graphics & CAD/CAM workstationslConnection device for host-to-host or

50、 Backbone-to-Backbone applications.67FDDI Strengths+ FDDI is tailor-made and very effective as a high-speed LAN for workstation traffic and as a Backbone for LANs.+ Provides a framework for inter-networking between various LAN protocols.68FDDI Strengths (Cont.)+ Compared to legacy LANs, FDDI provide

51、s greater data capacity and performance, transmitting at 100 Mbps.+ Can accommodate large networks of up to 500 Backbone nodes.69FDDI Strengths (Cont.)+ Because of its dual-ring architecture, FDDI offers a high degree of network availability/reliability.+ Using Token passing, traffic is dealt with o

52、n a deterministic basis. + Provides long distance communication (Ring perimeter can be 100 Km with a distance of up to 2Km between Stations)70FDDI Weaknesses- Can accommodate LAN traffic only. Not capable for transporting real-time signals (voice, host-to-terminal, etc.)- Non scaleable (fixed at 100

53、 Mbps). - High implementation cost (Processor intensive).71How FDDI Works?lIt is a token passing fiber ring with a data rate of 100 Mbps.lRing can be as large as 100 Km with a distance of 2 Km between stations.lMost prevalent standard is multi-mode fiber. However, some manufacturers are producing mu

54、lti-mode to single-mode FDDI adapter.72How FDDI Works? (Cont.)Others proposed amendments to the standard to support FDDI on twisted pair (CDDI).Routers are used to convert competing LAN protocols to FDDI and back.73How FDDI Works? (Cont.)lDual-counter rotating rings:lPrimary link for carrying data.l

55、Secondary link for failure recovery.lIn the event of a node or cable failure, the data on the primary link wraps on to the secondary link, making a U-turn, thus maintaining ring integrity.74How FDDI Works? (Cont.)FDDIFDDIFDDIXX75FDDI SpecificationlANSI Standard.lRing as large as 100 Km with a distan

56、ce of 2 Km between stations.l62.5 m core / 125 m cladding.l1300 nano-meter LED transmitterlTwo types of FDDI networking devices:lClass A devices have dual attachment.lClass B are typically workstations.76FDDI SpecificationlClass A DeviceslTo exploit counter-rotating rings. The failure wrapping featu

57、re is implemented through Class A devices.lCan be any networking device, but are usually Bridges, Routers, Concentrators, Servers, or other devices comprising the network Backbone.77Class A Devices (Cont.) Each dual-attached station constantly receives Handshaking information from its neighbors via

58、the secondary link. If station stops receiving Handshaking information, it wraps data from the primary to the secondary ring so that the disabled node is avoided and ring integrity is maintained.78FDDI Specification (Cont.)lClass B DeviceslThey are single-attached stations. lThey are typically works

59、tations, printers, and other nodes that are attached only indirectly to the primary link.lThey access the ring by plugging into a concentrator that is dual-attached to the ring.lAn FDDI network can operate with up to 500 dual-attached stations.79FDDI Specification (Cont.)AABBBBBBBBBBBClass A80FDDI F

60、ramePreamble (Beginning)Start of FrameFrame ControlDestination Source DataCRCEnd of FrameFrame Status (End)81Collapsed BackbonelBased on todays high-speed Routers.lSometimes called Backbone Routers.lThis scheme collapses vast amounts of enterprise data onto the backplane of a high-throughput Router.lLAN connections are starred back to the central co