WIXLIB

AgendaIntroductions to ISPDesign Fundamentals Rational Behind ISP Network Design Point of Presence Topologies Adding Services to the Architecture Impact of Services on the NetworkPresentation ID1 1999, Cisco Systems, Inc.Presentation ID 1999, Cisco Systems, Inc.www.cisco .com2The Free On-line Dictionaryof ComputingRational Behind ISPNetwork DesignArchitecture: Design; the waycomponents fit together;it may also be used for anycomplex system, e.g. “softwarearchitecture”, “networkarchitecture”Layers upon Layers upon Layersupon Layers .Presentation ID 1999, Cisco Systems, Inc.www.cisco .com3Presentation IDNetwork Design andArchitecture 1999, Cisco Systems, Inc.www.cisco .comFerguson’s Law ofEngineering“ can be critical can contribute to the successof the network can contribute to the failureof the networkNo amount of magicknobs will save asloppilydesigned networkPaul Ferguson—Consulting Engineer,Cisco SystemsPresentation ID 1999, Cisco Systems, Inc.www.cisco .com45Presentation IDCopyright 1998, Cisco Systems, Inc. All rights reserved. Printed in USA.Presentation ID.scr 1999, Cisco Systems, Inc.www.cisco .com”61

What Is a Well-DesignedNetwork?One Must Acknowledge that One that takes into considerationsome main factorsPresentation ID3 One3Topological/protocol hierarchy3Redundancy3Addressing aggregation (IGP and BGP)3Scaling3Policy implementation www.cisco .com 1999, Cisco Systems, Inc. Two different worlds existworld revolves around privateorganizational networks and anotherconcerns the global Internet Growth in the Internet is faster thanany other technology introduced tothe public-at-large7Presentation IDwww.cisco .com 1999, Cisco Systems, Inc.8Scaling is the #1 Problem onthe InternetTechnology AdoptionRadio“TVIf you’re not scared yet,you don’t understand ternetAirplane”CellPhoneMike O’Dell—Chief Scientist,UUnetSource: Forbes Magazine July 7th— 1997Presentation ID 1999, Cisco Systems, Inc.www.cisco .com9Presentation IDwww.cisco .com 1999, Cisco Systems, Inc.Core Influences to ISP Design10Modular DesignOrganize the Networkinto separate andrepeatable modules Modular Design Functional Design3 Backbone Tiered/Hierarchical DesignOther ISPsISP Services(DNS, Mail, News,FTP, WWW)Hosted ServicesBackbone linkto another PoPBackbone linkto another PoPNetworkCoreConsumer3 POP Multiple Levels of Redundancy3 Hosting Routing Protocol Hierarchy3 ISP Build for IP Forwarding First - thenadd servicesPresentation ID 1999, Cisco Systems, Inc.www.cisco .comConsumer CableDIAL AccessServicesServicesand xDSL AccessNx64customeraggregation layerNxT1/E1 customeraggregation layerNetworkOperationsCentreChannelised T1/E1 circuitsNx64 leased line circuit deliveryChannelised T3/E3 circuitsT1/E1 leased line circuit delivery3 Support/NOC11Presentation IDCopyright 1998, Cisco Systems, Inc. All rights reserved. Printed in USA.Presentation ID.scr 1999, Cisco Systems, Inc.www.cisco .com122

Tiered/Hierarchical NetworkDesignFunctional Design Flat - MeshedTopologies havenot scaled.how hard people have tried in the past) Each router/switch in a network has awell-defined set of functions. ISP Networks are a systems approachto design.www.cisco .com 1999, Cisco Systems, Inc.CoreOtherRegions Hierarchy is usedin network designsto scale thenetwork. The various boxes each with afunction interact with each other.Presentation IDOtherRegionsOtherRegions One Box cannot do everything! (no materDistributionLayerAccess Layer13Presentation IDMultiple Levels of Redundancywww.cisco .com 1999, Cisco Systems, Inc.14Multiple Levels of Redundancy Objectives - Triple Layered POPRedundancyBackbone3Lower-level failures are better3Lower-level failures may triggerhigher-level failures3L2: Two of everything at3L3: IGP and BGP provideredundancy and load balancing3L4: TCP re-transmissionsrecovers during the fail-over3As little user visibility of a fault as possible3Minimize the impact of any fault in any part of thenetwork.3Network needs to handle L2, L3, L4, and RouterfailureBackboneBorderPeerNetworksIntra-POP InterconnectPOP ssPresentation IDwww.cisco .com 1999, Cisco Systems, Inc.15Presentation ID 1999, Cisco Systems, Inc.Hierarchy of RoutingProtocols“BGP4Beware Block Diagram/ SlidewareDesign Gurus! They have gottenpeople and networks into trouble- including CiscoBGP4and OSPF/ISISPresentation ID 1999, Cisco Systems, Inc.”Static/BGP4BGP4LocalIXPwww.cisco .com16WarningOther ISPsFDDIwww.cisco .comCustomers17Presentation IDCopyright 1998, Cisco Systems, Inc. All rights reserved. Printed in USA.Presentation ID.scr 1999, Cisco Systems, Inc.www.cisco .com183

PoP DesignNeighboringPOPCore BackboneRoutersNeighboringPOPCore 1Core 2External BGP PeeringPoint of PresenceTopologiesPOPInterconnectMediumSW 1Access 1Access 2SW 2NAS 1NAS 2Dedicated AccessISP/IXPPresentation IDWorkshopswww.cisco.com 1999, Cisco Systems, Inc.19Presentation IDEarly Internet POPArchitecture - NSP3 Backbonetrunks3 Backbonetrunksat 155 Mb/smediainterconnectwithin POP:interconnectwithin POP:FDDIATM OC33 AdvancedOC3 backboneInternet routerT3 backboneInternet routerwww.cisco .com21Presentation IDInternet POP Architecture ‘97/’98 Internetwww.cisco .com 1999, Cisco Systems, Inc.22Internet POP Architecture ‘99/’01Backbone3 BackboneXXSwitched FDDI/Fast Ethernet3 Conventional 1999, Cisco Systems, Inc.155 Mb/sPOS/ATM3 SwitchedFDDI, Ethernet, SwitchedEthernetPresentation IDInternetBackbonePacket over SONET OC3ATM OC345 Mb/sHSSI3 Shared20Internet POP Architecture ‘96/’97InternetBackboneat 45 Mb/sPSTN/ISDNwww.cisco .com 1999, Cisco Systems, Inc.Backbonetrunks at622 Mb/s SRP Rings - High Speedof SDH combined with fastfailover and redundancy622 Mb/sPOS/ATMPacket over SONET OC12ATM OC12622 Mb/s ATM1 Gb/s Ethernet3 Switchedinterconnectwithin POP:ATM at OC3 AND OC12Ethernet ChannelGigabit Ethernet (early ’98)POSIP (late ‘98)3 HighDuplex Fast E, 155/622 Mb/s ATM, or1 Gb/s Ethernet3 Reducedport counts3 ReducedcomplexityOC12 backboneInternet router7xxx7xxx3 Proactive self healing3 GigabitGSRGSRbandwidth7xxx7xxx7xxxleased line aggregationPresentation ID 1999, Cisco Systems, Inc.www.cisco .com23Presentation IDCopyright 1998, Cisco Systems, Inc. All rights reserved. Printed in USA.Presentation ID.scr 1999, Cisco Systems, Inc.www.cisco .com244

Large POPs - add a 3rd layer3Problem: port density!3Solution: buy more routers!3Customer routers connect toaggregation routersPOP Interconnect SummaryInternetBackboneOC48FDDI100MbpsSRP2 x 622Mbpsor 2x2.5GBPacket over SONET OC3OC12ATM OC33Aggregation routers connect tobackbone routers3Scales nicely3X CRs to Y ARs to Z BRs3 .whereOC3Fast/Gig Ethernet100/1000MbpsPOSN x 155X Y Z3 Becareful not tooversubscribe!Presentation ID 1999, Cisco Systems, Inc.www.cisco .com25Presentation IDKey Design Principles333Presentation IDGSRPOSSyslog collector for allnetwork devices75077507Security Auditing Tools(NetSonar) IGP EIGRP, IS-IS,or OSPF3almost always IS-IS or OSPF3IS-IS, single level (usually L2)3OSPF, either single area or BB/POPareasBGP all routers in full mesh3SNMP collector (PC BasedUNIX) 1999, Cisco Systems, Inc.ISP routing Architectures - IP GSRNetflow Devices FlowCollector26POS & ATM for Core Backbone Interconnection forManagement, Security,and Accounting services3www.cisco .com 1999, Cisco Systems, Inc.Management& Accountingmesh accomplished with routereflectors, confederations, actual fullmeshAll routers have all routes, soservices could go anywhereCustomer and Serviceswww.cisco .com27Presentation ID 1999, Cisco Systems, Inc.www.cisco .com28ISP routing Architectures IP MPLS IGP EIGRP, IS-IS,or OSPF BGP only edge routers need full routes3 Adding Services to theArchitecturemust be IS-IS or OSPF to use MPLSTE3full-mesh of edge routers usingaforementioned mechanisms3packets are forwarded via LDPlabels, not IP destination addressCause and EffectWhere to put your services?3Presentation IDcannot hang a cache service off of arouter that doesn’t have full routes! 1999, Cisco Systems, Inc.www.cisco .com291503Presentation ID0925 04F9 c1Copyright 1998, Cisco Systems, Inc. All rights reserved. Printed in USA.Presentation ID.scr 1999, Cisco Systems, Inc.305

Services?How many Services?Ask the Right Questions What is the value of the service?Most network services are applied at the edge!Edge (one-time) services3 TechnicalPer-hop services Voice over IP MPLS packet forwarding MPLS VPNs DiffServ, other QoS CDNs Multicast Services3 Marchitecture What is the cost of the service? VPDNs3 Equipment? Managed services Dial—DSL—cablePresentation IDmerit3 Cost savings 1999, Cisco Systems, Inc.www.cisco .com31Presentation ID3 Trainingpeople to support it?3 Networkbuildouts /topology changes? 1999, Cisco Systems, Inc.www.cisco .com32Who Knows? What will be the impact on existing trafficloads/patterns?Impact of Services onthe Network Can the network deliver the performancethat your customers/applications desire?delay? jitter (delay variation)? Make sure to add capacity as you addservices - bandwidth is a must.1503Presentation ID0925 04F9 c133 1999, Cisco Systems, Inc.Presentation IDDeployment of New Services 1999, Cisco Systems, Inc.www.cisco .com34Deploying New Services Is more of a business decision Don’t feed the hype fire The technical aspect is to ensurecontinued network performance—scalability and stability Look before you leap! Don’t deploy new technologies andservices just for the sake of it; havevalid business and technical reasons Try to keep services within your AS3 end2end3 lessPresentation IDcontrollikelihood of failure/flaps 1999, Cisco Systems, Inc.www.cisco .com35Presentation IDCopyright 1998, Cisco Systems, Inc. All rights reserved. Printed in USA.Presentation ID.scr 1999, Cisco Systems, Inc.www.cisco .com366

Deploying New ServicesDeploying New ServicesServiceTerminateHere Usually a Service requires a TCP/UDPtermination (I.e. TCP’s three wayhandshake)MultiplePOP ServicesAccess Termination should happen out sideof the primary flow pathISDNPOTSLease LineCablexDSL Otherwise, the network is thendesigned around the single service.Primary Packet FlowCPECPEPresentation ID 1999, Cisco Systems, Inc.www.cisco .comLeased CoreInterconnect37Presentation IDPOPPOP 1999, Cisco Systems, Inc.CORECOREwww.cisco .com38Design Objectives for the ISP Transparent Redirection of a IP flowbased on source, destination, and/orport number.TransparentRedirection of a Flowin the POP Transparent Integration - norebuilding the POP to add thisservice.Factors that went into thedesign of WCCPPresentation ID 1999, Cisco Systems, Inc.www.cisco .com Failed open - if the service fails, itshould not effect the core IP servicenor any other services.39Presentation IDDesign Objectives for the ISPCPECPEPresentation ID 1999, Cisco Systems, Inc.POPPOPwww.cisco .comWCCPServiceClustersAccessISDNPOTSLease LineCablexDSLPrimary Packet FlowInterconnect40 Work with the multi-level L2/L3 redundancyof the ISP POP. Equal paths in the IGP CEF leads packet asymmetry.WCCPServiceClustersAccesswww.cisco .comDesign Objectives for the ISP Not to effect the primary packet flow of thePOP - if not redirected - then is CEF/dCEFSwitched!ISDNPOTSLease LineCablexDSL 1999, Cisco Systems, Inc.Leased CoreInput tation IDCopyright 1998, Cisco Systems, Inc. All rights reserved. Printed in USA.Presentation ID.scr 1999, Cisco Systems, Inc.POPPOPwww.cisco .comLeased CoreCORECORE427