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

1、1Structured Backbone Design of CNs Habib Youssef, Ph.D.saDepartment of Computer Engineering King Fahd University of Petroleum & MineralsDhahran, Saudi A.saComputer Networks2Outline1. Enterprise Backbone Basics2. Structured Cabling3. Types of Backbones4. Backbon

2、e Examples 5. The Network Development Life Cycle (NDLC)3Enterprise Backbone BasicslModern organizations havelLarge networkslComplex communication requirementslAccess to mainframe datalInternetworking of several LANslConnectivity to a WAN (the Internet)lTransmission of data and non-data4Backbone Basi

3、cs (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 Backbone solution provide a powerful and efficient networking solution to company-wide comm

4、unication needs.5Backbone Basics (Cont.)lKey Factors in assessing network topologies:lPerformancelHighest network availability.lLowest latency.lMost appropriate connectivity for users.lScalabilitylAbility to expand the network in terms of end-points and aggregate bandwidth without affecting existing

5、 users.6Backbone 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 solutions offer Flexibility Scalability Troubleshooting & Manageability Performance7Structur

6、ed 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 should follow a cabling plan:lSelection of cable typeslCable layout topology8Structured Cab

7、ling 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 Standards are similar.9Structured Cabling (Cont.)lIt is a generic wiring scheme with the follow

8、ing 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 to encompass distribution to all work areas within the building (relocation wouldnt need r

9、ewiring).10Structured 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 Distribution Cable.lTypically, first level of distribution consists of Backbone cables.lBa

10、ckbone cable(s) run from ER to Telecom Closets (Wiring Closets) on each floor.11Structured Cabling (Cont.) Wiring Closet contains cross-connect equipment for interconnecting cable on a single floor to the Backbone. Cable distributed on a single floor is called Horizontal Cabling, and connects the Ba

11、ckbone to Wall Outlets that service individual telephone and data equipment.12Structured Cabling (Cont.)lBased on the use of a hierarchical star-wired cable layout.ExternalCableTelecom.ClosetEquipmentRoomBackboneHorizontalCableWorkArea13Structured Cabling TerminologyBackboneA facility between teleco

12、mmunications 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 cross-connect14Terminology (Cont.)Cross-ConnectA facility enabling the termination of ca

13、ble 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/Campus distributor in ISO 11801)15Terminology (Cont.)Telecommunications Closet:An enclos

14、ed 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 interact with the telecom terminal eqpt16Terminology (Cont.)Main Cross-ConnectA cross-connec

15、t 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)17Terminology (Cont.)Horizontal Cross-Connect:A cross-connect of horizontal cabling to other cabling, e.g.

16、 horizontal, backbone, or equipment (no ISO name)Telecommunications OutletA connecting device in the work area on which horizontal cable terminates18Media RecommendedTelecomm.OutletHorizontalCross-connectMainCrossconnectIntermediateCross-connectTelecomm.OutletHorizontalCross-connectACBDD19Cable Dist

17、anceslUTP (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 90m90m20Cable Distances (Cont.)l62.5 microns FiberlMC-HC HC-ICMC-ICTO -HClA BC Dl 2000m500m 1500m90mlSingle-Mode FiberlA BC Dl3000m500m 2500m90

18、m21Unstructured Backbone - MainframeTerminalsMainframe.Cluttered and noisycable risers.22Unstructured Backbone - LANEach station must be physically connected by a thick coax tapped to the LAN coax, running by all stations.23Structured BackbonelBy using a MUX or similar device, a backbone can be stru

19、ctured.lA single fiber pair replaces mounds of coax cable, andlfloor-to-floor traffic is systematically organized.lWith Structure comes enhancedlnetwork controllreliability, andlefficiency.24Structured Backbone (Cont.)lStructured backbone = structured, hierarchical physical star wiring scheme.Mainfr

20、ameMUXMUXMUX25Structured 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 signals to / from users distributed throughout the enterprise.lEarly backbones were mainly mux

21、es.26Structured 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 anlintelligent cabling Hub.lThe Backbone portion:lFacilitating floor-to-floor or buildi

22、ng-to-buildinglconnectivity.27Structured Backbone (Cont.) The Wide Area Network linkHorizontalaccessBackboneWANInterface28When are Backbones needed?lCompanies utilizing Backbone techno-logy have typically one or more of the following communication needs:lMultiple data protocols and signals.lHeavy ne

23、twork 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.29When are Backbones needed? (Cont.) Need to support varying media and device types. A high degr

24、ee 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 that the enterprise network be highly manageable.30Types of (private) BackbonesThree br

25、oad categories:(1) Multiplexers-based.(2) LAN Backbones.FDDI, Ethernet, Token Ring, etc(3) Collapsed Backbones.High-speed Router, ATM. 31Public BackbonesPublic telephone/data network32Backbone TopologieslStarlCollapsed BackbonelPBX systemlSwitch-based networks33Backbone Topologies (Cont.)lRing. lEx:

26、 FDDI.34Backbone Topologies (Cont.)lHierarchical/Inverse Tree.lHigher power at higher levels.35Backbone Topologies (Cont.)lMesh.lMultiple data paths between peer stations.lTopology relies on the use of Routers.36Backbone Benefits+ Makes complex distributed computing environment easier to manage.+ Al

27、lows Organizations to easily upgrade the system.+ Creates an integrated communication path capable of accommodating the enterprises data transfer requirements safely and cost effectively.37Fiber OpticslMany of the Backbone advantages are enabled by the implementation of fiber.lAdvantages of fiber:l+

28、 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 & reliability.38Application / BandwidthlHigh capacity Backbone is a must to support increasing

29、 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 video1 - 2 Gbpsl Chest X-Ray4 - 40 Mbpsl Remote query burst1 Mbps39Multiplexer-Based Bac

30、kboneslThe 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 supported via a common Backbone.lA Mux is a device that simultaneously transmits several

31、 messages or signals across a single channel or data path.40Multiplexer-Based BackboneslTwo primary types of Backbone Muxes in use today:lTime Division Mux (TDM).lStatistical or Stat Mux.41Time Division MuxeslA TDM combines signals onto a high speed link, and then sends those signals sequentially at

32、 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.42Time Division MuxesEthernetToken RingMainframeEthernetToken RingMainframeMTEMTEMTEMTE.Aggregate pathwayMuxingDe-Muxing43T

33、DM Strengths+ Dedicated bandwidth partitions= Guaranteed throughput & no loss.+ Versatile & scaleable.+ Low cost compared to Stat. TDM.+ Proven Reliable data transport.44TDM Weaknesses- Bandwidth of idle sources is lost.- Minimal internetworking capability. 45Statistical TDMlBased on the pre

34、mise 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 bandwidth.lAllocates time slots on-demand, constantly evaluating traffic needing to be sent

35、 (based on priority). 46Stat-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 management.lGreater degree of intelligence.lGreater computer power.47Stat-Mux Strengths+ Suppo

36、rts more data than available bandwidth= better bandwidth utilization.+ Critical data can be given higher priority.48Stat-Mux Weaknesses- Requires more management and more expensive to operate.- Low priority data can suffer excessive delays.- Data may get lost. (No guaranteed bandwidth)49Emerging Bac

37、kbone TechnologieslThree of the most promising Backbone technologies are:lAsynchronous Transfer Mode (ATM).lSynchronous Optical Network (SONET).lFibre Channel.50ATMlTodays collapsed Backbones are based on Router technology.lTomorrows collapsed Backbones will be based on switching technology.lATM is

38、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.51ATM (Cont.)ATMATMServerWANInterfaceRouterBackbone52ATM Benefits+ Combines best features of Muxes and LAN Backbones.+ ATM rides on top of a highly scaleabl

39、e 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.53ATM Benefits (Cont.)+ Provides high throughput.+ ATM is not protocol-dependent. Any packet format can be

40、mapped into ATM cells and transported.= It is an ideal data transfer system for changing LAN environments.54How ATM Works?lData Units: Fixed-length cells of size 53 bytes each (5 Header + 48 payload).lOperates at the equivalent of MAC sublayer. Operates above physical layer which could be SONET, Fib

41、re channel,.lConnection-oriented.lUniversal transfer mode for all B-ISDN services.lLayered architecture. 55ATM Layered ArchitectureHigher LayersUser Services & applicationsATM Adaptation LayerATM LayerPhysical MediumDependent LayerFragmentation andde-fragmentation of framesCell header insertion/

42、removalCell relaying & multiplexingConnection establishmentTransmission & receipt of bitsSynchronization56How ATM Works?Data packetAALATMPhysical Layer57How ATM Works (Cont.)?Physical LayerATMEntire process is reversedOverheadEnvelopeCell58Examples of ATM SwitcheslFORE SystemslASX-200BX (2.5

43、 Gbps backplane)lASX-1000 (10 Gbps backplane)lCISCO SystemslNWAYS 8260 (5 Gbps backplane)lBay NetworkslCentillian-100: campus ATM switchl(3.2 Gbps backplane)59Examples of ATM Switches (Cont.)lIBM lNWAYS 8260 (5 Gbps backplane)lMADGE NetworkslCollage 740: Campus ATM switchl(5 Gbps backplane)lALCATELl

44、1100 LSS Series 550A60Synchronous 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 Standard:Rates start at OC-1:51.84 MbpsScaling up to OC-48: 2.48 Gbps61SONET (Cont.)lEurope

45、an 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 with single mode fiber.62Fibre ChannellANSI X3T9.3 Standard.lDeveloped as high speed inter

46、face for linking mainframes and their peripherals.lBetter suited as a private Backbone becauselless overheadllowest implementationlmulti-mode fiber63Fibre Channel (Cont.)Is also highly expandableInitial Rate: 100 MbpsScales up to: 1.6 GbpsHas a transport payload envelope64LAN BackboneslUnlike Muxes

47、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 can be called a backbonelLANs constitute the primary datapaths.65LAN Backbones (Cont.)lIn

48、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 provides standards-based connectivity for legacy LANs (Ethernet & Token Ring).66LAN Backb

49、ones (Cont.)Token RingEthernetToken RingEthernetEthernetToken RingAll of the protocols areconverted to the FDDI transport protocolData is Bridged/Routed from the high-speed Backbone to destination LAN67LAN Backbones (Cont.)lFDDI complements existing LANs by providing a high-speed path upon which all

50、 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 Backbone-to-Backbone applications.68FDDI Strengths+ FDDI is tailor-made and very effect

51、ive as a high-speed LAN for workstation traffic and as a Backbone for LANs.+ Provides a framework for inter-networking between various LAN protocols.69FDDI Strengths (Cont.)+ Compared to legacy LANs, FDDI provides greater data capacity and performance, transmitting at 100 Mbps.+ Can accommodate larg

52、e networks of up to 500 Backbone nodes.70FDDI Strengths (Cont.)+ Because of its dual-ring architecture, FDDI offers a high degree of network availability/reliability.+ Using Token passing, traffic is dealt with on a deterministic basis. + Provides long distance communication (Ring perimeter can be 1

53、00 Km with a distance of up to 2Km between Stations)71FDDI Weaknesses- Can accommodate LAN traffic only. Not capable for transporting real-time signals (voice, host-to-terminal, etc.)- Non scaleable (fixed at 100 Mbps). - High implementation cost (Processor intensive).72How FDDI Works?lIt is a token

54、 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 multi-mode to single-mode FDDI adapter.73How FDDI Works? (Cont.)Others proposed amendments

55、 to the standard to support FDDI on twisted pair (CDDI).Routers are used to convert competing LAN protocols to FDDI and back.74How FDDI Works? (Cont.)lDual-counter rotating rings:lPrimary link for carrying data.lSecondary link for failure recovery.lIn the event of a node or cable failure, the data o

56、n the primary link wraps on to the secondary link, making a U-turn, thus maintaining ring integrity.75How FDDI Works? (Cont.)FDDIFDDIFDDIXX76FDDI SpecificationlANSI Standard.lRing as large as 100 Km with a distance of 2 Km between stations.l62.5 m core / 125 m cladding.l1300 nano-meter LED transmitt

57、erlTwo types of FDDI networking devices:lClass A devices have dual attachment.lClass B are typically workstations.77FDDI SpecificationlClass A DeviceslTo exploit counter-rotating rings. The failure wrapping feature is implemented through Class A devices.lCan be any networking device, but are usually

58、 Bridges, Routers, Concentrators, Servers, or other devices comprising the network Backbone.78Class A Devices (Cont.) Each dual-attached station constantly receives Handshaking information from its neighbors via the secondary link. If station stops receiving Handshaking information, it wraps data fr

59、om the primary to the secondary ring so that the disabled node is avoided and ring integrity is maintained.79FDDI Specification (Cont.)lClass B DeviceslThey are single-attached stations. lThey are typically workstations, printers, and other nodes that are attached only indirectly to the primary link

60、.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.80FDDI Specification (Cont.)AABBBBBBBBBBBClass A81FDDI FramePreamble (Beginning)Start of FrameFrame ControlDestination Source DataCRCEnd of FrameFrame Status (End)82Collapsed BackbonelBased on to