Narrowing the Beam: Lowering Complexity in Cellular Networks by Scaling Up

Software Defined NetworkingCOMS 6998-8, Fall 2013Instructor: Li Erran Li (lierranli@cs.columbia.edu)http://www.cs.columbia.edu/~lierranli/coms6998-8SDNFall2013/9/3/2013: Class Intro and Pre-SDN1OutlinePart I: Course Introduction and LogisticsPart II: Precursor to SDNSoftware Defined Networking (COMS 6998-8)2Part I: Course Introduction and Logistics IntroductionMy researchSDNCourse syllabusCourse goals and structureExample projectsSoftware Defined Networking (COMS 6998-8)3IntroductionResearcher at Bell Labs, Alcatel-LucentPh.D. from Dept. of CS, Cornell, 2001Research interest: software defined networking, mobile computing, cloud computing, and security Research Goal: improve our mobile user experience through innovation in network architecture, mobile cloud computing systems and securitySoftware Defined Networking (COMS 6998-8)4ExperiencesRelevant working experiencesSoftware defined networkingSoftware defined cellular core networks (SoftCell, Princeton TR13), Software defined radio access networks (SoftRAN, HotSDN13), Mobile computing: mobile cloud computingCloud computing: scaling out enterprise applications, cloud-based video proxy, policy-aware enterprise application cloud extension

Software Defined Networking (COMS 6998-8)5Experiences (Contd)Professional ActivitiesACM Workshop on Cellular Networks: Operations, Challenges, and Future Design (CellNet), 2012-2013DIMACS Workshop on Software Defined Networking, Dec, 2012ACM MobiSys Workshop on Mobile Cloud Computing & Services: Social Networks and Beyond (MCS), June 2010 DIMACS Workshop on Systems and Networking Advances in Cloud Computing, Dec, 2011

TeachingCellular Networks and Mobile Computing (Spring 2012, Fall 2012, Spring 2013)

Software Defined Networking (COMS 6998-8)6Brief Introduction to SDNWhat is software defined networking?Why SDN?How has SDN been shaping networking research and industry?Software Defined Networking (COMS 6998-8)7Vertically integratedClosed, proprietarySlow innovationSmall industry

SpecializedOperatingSystemSpecializedHardwareAppAppAppAppAppAppAppAppAppAppAppSpecializedApplicationsHorizontalOpen interfacesRapid innovationHuge industryMicroprocessor

Open InterfaceLinuxMacOSWindows(OS)ororOpen InterfaceSoftware Defined Networking (COMS 6998-8)8Source: Nick Mckeown, StanfordThe mainframe industry in the 1980s was vertical and closed: it consisted of specialized hardware, operating system and applications --- all from the same company. A revolution happened when open interfaces started to appear. The industry became horizontal. Innovation exploded. 8Vertically integratedClosed, proprietarySlow innovationAppAppAppAppAppAppAppAppAppAppAppHorizontalOpen interfacesRapid innovationControlPlaneControlPlaneControlPlaneororOpen Interface

SpecializedControlPlaneSpecializedHardwareSpecializedFeaturesMerchantSwitching ChipsOpen Interface

Software Defined Networking (COMS 6998-8)9Source: Nick Mckeown, Stanford9Million of linesof source code6,000 RFCsBillions of gatesBloatedPower Hungry Vertically integrated, complex, closed, proprietary Networking industry with mainframe mind-set

Custom HardwareOSRouting, management, mobility management, access control, VPNs, FeatureFeature

Software Defined Networking (COMS 6998-8)10Source: Nick Mckeown, Stanford10Custom HardwareCustom HardwareCustom HardwareCustom HardwareCustom HardwareOSOSOSOSOSNetwork OSFeatureFeatureThe network is changingFeatureFeatureFeatureFeatureFeatureFeatureFeatureFeatureFeatureFeatureSoftware Defined Networking (COMS 6998-8)11Source: Nick Mckeown, StanfordFeatureFeatureNetwork OS1. Open interface to packet forwarding3. Consistent, up-to-date global network view2. At least one Network OSprobably many.Open- and closed-sourceSoftware Defined Network (SDN)PacketForwarding

PacketForwarding

PacketForwarding

PacketForwarding

PacketForwarding

Software Defined Networking (COMS 6998-8)12Source: Nick Mckeown, StanfordNetwork OSNetwork OS: distributed system that creates a consistent, up-to-date network viewRuns on servers (controllers) in the networkFloodlight, POX, Pyretic, Nettle ONIX, Beacon, + more

Uses forwarding abstraction to:Get state information from forwarding elementsGive control directives to forwarding elements

Software Defined Networking (COMS 6998-8)13Source: Nick Mckeown, StanfordControl Program AControl Program BNetwork OSSoftware Defined Network (SDN)PacketForwarding

PacketForwarding

PacketForwarding

PacketForwarding

PacketForwarding

Software Defined Networking (COMS 6998-8)14Source: Nick Mckeown, StanfordControl ProgramControl program operates on view of networkInput: global network view (graph/database)Output: configuration of each network device

Control program is not a distributed systemAbstraction hides details of distributed state

Software Defined Networking (COMS 6998-8)15Source: Nick Mckeown, StanfordForwarding AbstractionPurpose: Abstract away forwarding hardwareFlexibleBehavior specified by control planeBuilt from basic set of forwarding primitivesMinimalStreamlined for speed and low-powerControl program not vendor-specific

OpenFlow is an example of such an abstraction

Software Defined Networking (COMS 6998-8)16Source: Nick Mckeown, StanfordOpenFlow BasicsSoftware Defined Networking (COMS 6998-8)171717OpenFlow ProtocolData Path (Hardware)Control PathOpenFlow

Ethernet SwitchNetwork OSControl Program AControl Program BOpenFlow BasicsSoftware Defined Networking (COMS 6998-8)18Source: Nick Mckeown, Stanford18Control Program AControl Program BNetwork OSOpenFlow BasicsPacketForwarding

PacketForwarding

PacketForwarding

FlowTable(s)If header = p, send to port 4If header = ?, send to meIf header = q, overwrite header with r, add header s, and send to ports 5,6Software Defined Networking (COMS 6998-8)19Source: Nick Mckeown, StanfordPlumbing Primitives

Match arbitrary bits in headers:

Match on any header, or new headerAllows any flow granularity

ActionForward to port(s), drop, send to controllerOverwrite header with mask, push or popForward at specific bit-rate20HeaderDataMatch: 1000x01xx0101001xSoftware Defined Networking (COMS 6998-8)Source: Nick Mckeown, StanfordGeneral Forwarding AbstractionSmall set of primitivesForwarding instruction setProtocol independentBackward compatibleSwitches, routers, WiFi APs, basestations, TDM/WDMSoftware Defined Networking (COMS 6998-8)21Source: Nick Mckeown, StanfordWhy SDN?Great talk by Scott Shenkerhttp://www.youtube.com/watch?v=WVs7Pc99S7w(Story summarized here)NetworkingNetworking is Intellectually WeakNetworking is behind other fieldsNetworking is about the mastery of complexity

Good abstractions tame complexityInterfaces are instances of those abstractions

No abstraction => increasing complexityWe are now at the complexity limitSoftware Defined Networking (COMS 6998-8)23Source: Nick Mckeown, Stanford23By comparison: ProgrammingMachine languages: no abstractionsHad to deal with low-level detailsHigher-level languages: OS and other abstractionsFile system, virtual memory, abstract data types, ...Modern languages: even more abstractionsObject orientation, garbage collection,Software Defined Networking (COMS 6998-8)24Source: Nick Mckeown, StanfordProgramming AnalogyWhat if programmers had to:Specify where each bit was storedExplicitly deal with internal communication errorsWithin a programming language with limited expressabilityProgrammers would redefine problem by:Defining higher level abstractions for memoryBuilding on reliable communication primitivesUsing a more general languageSoftware Defined Networking (COMS 6998-8)25Source: Nick Mckeown, StanfordSpecification AbstractionNetwork OS eases implementationNext step is to ease specification

Provide abstract view of network mapControl program operates on abstract viewDevelop means to simplify specificationSoftware Defined Networking (COMS 6998-8)26Source: Nick Mckeown, StanfordControl Program AControl Program BSoftware Defined Network (SDN)PacketForwarding

PacketForwarding

PacketForwarding

PacketForwarding

PacketForwarding

Network OSGlobal Network ViewAbstract Network ViewVirtualizationSoftware Defined Networking (COMS 6998-8)27Source: Nick Mckeown, StanfordHow SDN shaping Industry?Open Networking Foundation (ONF)New non-profit standards organization (Mar 2011)Defining standards for SDN, starting with OpenFlowBoard of DirectorsGoogle, Facebook, Microsoft, Yahoo, DT, Verizon39 Member Companies Cisco, VMware, IBM, Juniper, HP, Broadcom, Citrix, NTT, Intel, Ericsson, Dell, Huawei, OpenDaylight led by IBM and CiscoMission is to develop open source SDN platform

Software Defined Networking (COMS 6998-8)28How SDN shaping Industry (Contd)Cellular industryRecently made transition to IPBillions of mobile usersNeed to securely extract payments and hold users accountableIP is bad at both, yet hard to change

SDN enables industry to customize their network

Software Defined Networking (COMS 6998-8)29How SDN shaping Industry (Contd)

Cost200,000 serversFanout of 20 10,000 switches$5k vendor switch = $50M$1k commodity switch = $10M

Savings in 10 data centers = $400M

Control

More flexible controlTailor network for servicesQuickly improve and innovateData CenterSoftware Defined Networking (COMS 6998-8)30Source: Nick Mckeown, StanfordHow SDN shaping Industry (Contd)Big companiesGoogle B4: deployed SDN to manage cross data center trafficMicrosoft SWAN: software defined WANFacebook: infrastructure team exploring SDNVmware: Nicira, overlay approach to SDNIntel: OpenFlow switch Cisco: OpenFlow switchSoftware Defined Networking (COMS 6998-8)31How SDN shaping Industry (Contd)StartupsAffirmed Networks: virtualized subscriber and content management tools for mobile operatorsBig Switch Networks: OpenFlow-based SDN switches, controllers and monitoring toolsEmbrane: layer 3-7 SDN services to enterprises and service providersAccelera: software defined wireless networks funded by Stanford Professor Andrea GoldsmithSoftware Defined Networking (COMS 6998-8)32How SDN shaping Research?Ease of trying new ideasExisting tools: NOX, Beacon, switches, MininetMore rapid technology transferGENI, Ofelia and many more

A stronger foundation to build uponProvable properties of forwardingNew languages and specification toolsSoftware Defined Networking (COMS 6998-8)33How SDN shaping Research (Contd)Research activitiesOpen Networking Summit started in 2011ACM HotSDN workshop started in 2012ACM SIGCOMM, USENIX NSDI sessions Software Defined Networking (COMS 6998-8)34Course SyllabusSDN Basics and Scalability (Lecture 2, 3)OpenFlow, Floodlight, POX, mininet, CbenchScalable control plane: hierarchical controller, logical crossbarScalable data planeSDN Abstraction (Lecture 4, 5, 6)Programming language, verification, network updateProgrammable Data Plane (Lecture 7) Protocol independent forwarding, Click modular router, SwitchBladeSDN Application (Lecture 8, 9, 10)Virtualization, traffic management, wireless networksSDN Endhosts, Middleboxes and Storage (Lecture 11)SDN Debugging, Fault Tolerance and Security (Lecture 12)Software Defined Networking (COMS 6998-8)35Course Goals and StructureThe course equips you to address the following questions:What is software defined networking?What are the key building blocks?How do I use SDN to solve enterprise, carrier, and data center/cloud networking problems?What is the future of SDN? Software Defined Networking (COMS 6998-8)36Understanding the interplay of cellular networks and mobile computing through measurements Cellular aware mobile application design36Course Goals and Structure (Contd)The course emphasizes concepts, handson experiences and researchMidterm will be on concepts (30% of grade)Two programming assignments (one on Floodlight and the other on Pyretic) (20% of grade)Course projects (50% of grade)Software Defined Networking (COMS 6998-8)37Understanding the interplay of cellular networks and mobile computing through measurements Cellular aware mobile application design37Research ProjectTopicChoose from a list of topicsCome up with your own topicMust be related to software defined networking, ideally solves a real problemShould contain some research elements, e.g. scalable system design, novel algorithmsTeams of 1 to 4 studentsFinal deliverablesProject report (research paper format, 10 to 12 pages)Project presentation and demo Software Defined Networking (COMS 6998-8)38Research Project (Contd)Precisely define the projectUnderstand related workPropose novel techniques or systemsCreativity will be evaluatedSystem implementationController platform: Floodlight, POX, Pyretic, NettleTesting: mininet, Cbench (controller benchmark tool)

Software Defined Networking (COMS 6998-8)39Research Project (Contd)Evaluate your solution, e.g. performance, scalabilityThoroughness will be evaluatedWrite up and present your projectsEvaluated using professional paper review criterions

Project timelines (suggested)September 17: Form final project teamOctober 8: project description (2-4 pages)December 3: final presentation and demoDecember 10: final project report (10-12 pages)I will meet with you regularly

Software Defined Networking (COMS 6998-8)40List of Suggested ProjectsCellular network virtualizationProgramming language abstraction for wireless networksSDN to improve video applicationsSDN measurement primitivesSDN testing and debuggingSDN security: mitigate DDoS attacksSoftware Defined Networking (COMS 6998-8)41Class ResourcesCourse web page: schedule, project timelines, list of potential projects, etcPiazza page for discussionOnline resourcesCOS-597E, Princeton University, Fall 2013CSE690-01, Stony Brook University, Fall 2013Coursera Software Defined Networking by Dr. Nick Feamster SDN reading listOpen Networking SummitFor any questions or concerns: email me at lierranli@cs.columbia.eduTA: YoungHoon Jung, jung@cs.columbia.eduSoftware Defined Networking (COMS 6998-8)42Part II: Precursor to SDNAT&Ts Network Control Points: separation of control plane and data plane in circuit switched networks (dates back to 1980s)Routing control platform (2004)A Clean Slate 4D Approach to Network Control and Management (2005)Software Defined Networking (COMS 6998-8)43Routing control platform (RCP) Software Defined Networking (COMS 6998-8)4445How ISPs routeBorder router

Internal routerProvide internal reachability (IGP)Learn routes to external destinations (eBGP)Distribute externally learned routes internally (iBGP)Select closest egress (IGP)62492133Software Defined Networking (COMS 6998-8)Source: Matthew Caesar, UIUC45Say There are four parts to internet routing (dont say in route selection)46Whats wrong with Internet routing?Full-mesh iBGP doesnt scale# sessions, control traffic, router memory/cpuRoute-reflectors help by introducing hierarchybut introduce configuration complexity, protocol oscillations/loopsHard to manageMany highly configurable mechanismsDifficult to model effects of configuration changesHard to diagnose when things go wrongHard to evolveHard to provide new services, improve upon protocols

Software Defined Networking (COMS 6998-8)Source: Matthew Caesar, UIUC4647Routing Control PlatformWhats causing these problems?Each router has limited visibility of IGP and BGPNo central point of control/observationResource limitations on legacy routersnetworkRCPSolution: compute routes from central point, remove protocols from routersnetworknetworkRCPInter-AS ProtocolRCPSoftware Defined Networking (COMS 6998-8)Source: Matthew Caesar, UIUC47Why drawing RCP above network boxes just say orally, that its not part of the forawarind plane48RCP in a single ISPBetter scalability: reduces load on routersEasier management: configuration from a single pointEasier evolvability: freedom from router softwareRCP

iBGPSoftware Defined Networking (COMS 6998-8)Source: Matthew Caesar, UIUC48Then bring up 3 points after describe slide (Animate)On this slide say what it is that yuouve impelemntede, this is an imprlmentation that emultates full mesh, empasisze per router decision making - very important piont to bring up!!! Say why is not just a route reflector.

Put text on slide to say why arrows going in both directions, available routes up and assigned routes down.Reduce number of routers, just show some on maybe just internal ones send up igp. Maybe just say gets igp, and take out lines to internal routers.49RCP architectureDivide design into componentsReplication improves availabilityDistributed operation, but global state per component

Route Control Server (RCS)BGP EngineIGP Viewer(NSDI 04)Routing Control Platform (RCP)

Available BGP routesBGP updatesSelected BGP routesBGP updatesPath cost matrixIGP link-state advertisementsSoftware Defined Networking (COMS 6998-8)Source: Matthew Caesar, UIUC4950Challenges and contributionsReliabilityProblem: single point of failureContribution: simple replication of RCP componentsConsistencyProblem: inconsistent decisions by replicasContribution: guaranteed consistency without inter-replica protocolScalabilityProblem: storing all routes increases cpu/memory usageContribution : can support large ISP in one computer Building this system is feasibleSoftware Defined Networking (COMS 6998-8)Source: Matthew Caesar, UIUC50Rest of talk about how build thing, how to build for one isp, say will focus on last two points!51Potential consistency problemNeed to ensure routes are consistently assigned Even in presence of failures/partitions

ABCDUse egress C (hence use A as your next-hop)Use egress D (hence use B as your next-hop)RCP 1RCP 2Software Defined Networking (COMS 6998-8)Source: Matthew Caesar, UIUC5152Consistent assignmentSingle RCP, single partitionSolution: Assign all routers along the shortest IGP path the same exit routerEnsures forwarding loops dont ariseRCP 1

BAUse egress BUse egress ASoftware Defined Networking (COMS 6998-8)Source: Matthew Caesar, UIUC5253Consistent assignment Single RCP, multiple partitionsSolution: Only use state from routers partition in assigning its routes Ensures next hop is reachable

Partition 1Partition 2RCP 1Software Defined Networking (COMS 6998-8)Source: Matthew Caesar, UIUC5354Consistent assignment Multiple RCPs, multiple partitionsSolution: RCPs receive same IGP/BGP state from each partition they can reachIGP provides complete visibility and connectivityRCS only acts on partition if it has complete state for itPartition 1Partition 2Partition 3RCP 2RCP 1No consistency protocol needed to guarantee consistency in steady stateSoftware Defined Networking (COMS 6998-8)Source: Matthew Caesar, UIUC54Need to stress ibgp connectivity is ensured thru igp connectivitySay what a partition is, say explicitly that RCP is not in IGP forwarding plane say this earlier. Otherwise not clear what partitoin is and why cant route through rcs1 eg55Scalability solutionEliminate redundancyStore only a single copy of each BGP routeAccelerate lookupQuickly find routers whose routes changed Avoid recomputationCompute routes once for groups of routersDont recompute if relative ranking of egress routers unchangedSoftware Defined Networking (COMS 6998-8)Source: Matthew Caesar, UIUC55Talk about next slide in terms of these three points, eg you could say explicitly, to avoid redundancy we build redundancy using ZZZA Clean Slate 4D Approach to Network Control and Management Software Defined Networking (COMS 6998-8)56MotivationData plane handles individual packetsControl planeimplements distributed routing algorithmsManagement planemonitors the networkconfigures the data/control plane

Many dependencies among statesHowever, most of them maintained manuallyFundamental Problem

Router ID (sorted by file size)Lines in config fileSize of configuration files in a single enterprise network (881 routers)Software Defined Networking (COMS 6998-8)58Reachability ExampleTwo locations, each with data center & front officeAll routers exchange routes over all links

R1

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R5

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R3Chicago (chi)New York (nyc)

Data CenterFront Office

Software Defined Networking (COMS 6998-8)59Reachability Example

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R3Chicago (chi)New York (nyc)

Data Center

chi-DCchi-FOnyc-DCnyc-FOchi-DCchi-FOnyc-DCnyc-FOFront OfficeSoftware Defined Networking (COMS 6998-8)60Reachability Example

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Data Center

chi-DCchi-FOnyc-DCnyc-FOchi-DCchi-FOnyc-DCnyc-FOPacket filter:Drop nyc-FO -> *Permit *Packet filter:Drop chi-FO -> *Permit *Front OfficechinycSoftware Defined Networking (COMS 6998-8)61Reachability ExampleA new short-cut link added between data centersIntended for backup traffic between centers

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Packet filter:Drop nyc-FO -> *Permit *Packet filter:Drop chi-FO -> *Permit *Front OfficechinycSoftware Defined Networking (COMS 6998-8)62Reachability ExampleOops new link lets packets violate security policy!Routing changed, butPacket filters dont update automatically

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Packet filter:Drop nyc-FO -> *Permit *Packet filter:Drop chi-FO -> *Permit *Front OfficechinycSoftware Defined Networking (COMS 6998-8)63The 4D ArchitecturePropose a clean-slate repartitioning of functionality, rather than exploring incremental extensions

Completely separate decision logic (network issues) from underlying protocols (distributed systems issues)Software Defined Networking (COMS 6998-8)64Three Principles forNetwork Control & ManagementNetwork-level Objectives:Express goals explicitlySecurity policies, QoS, egress point selectionDo not bury goals in box-specific configurationManagementLogicReachability matrixTraffic engineering rules

Software Defined Networking (COMS 6998-8)65Three Principles forNetwork Control & ManagementNetwork-wide Views:Design network to provide timely, accurate infoTopology, traffic, resource limitationsGive logic the inputs it needs

ManagementLogicReachability matrixTraffic engineering rulesRead state infoSoftware Defined Networking (COMS 6998-8)66Three Principles forNetwork Control & ManagementDirect Control:Allow logic to directly set forwarding stateFIB entries, packet filters, queuing parametersLogic computes desired network state, let it implement it

ManagementLogicReachability matrixTraffic engineering rulesRead state infoWrite state Software Defined Networking (COMS 6998-8)67Layers of the 4D ArchitectureDecision Plane:All management logic implemented on centralized servers making all decisionsDecision Elements use views to compute data plane state that meets objectives, then directly writes this state to routersDecisionDisseminationDiscoveryDataNetwork-level objectivesDirect controlNetwork-wide viewsSoftware Defined Networking (COMS 6998-8)68Layers of the 4D ArchitectureDissemination Plane:Provides a robust communication channel to each router and robustness is the only goal!May run over same links as user data, but logically separate and independently controlledDecisionDisseminationDiscoveryDataNetwork-level objectivesDirect controlNetwork-wide viewsSoftware Defined Networking (COMS 6998-8)69Layers of the 4D ArchitectureDiscovery Plane:Each router discovers its own resources and its local environmentE.g., the identity of its immediate neighborsDecisionDisseminationDiscoveryDataNetwork-level objectivesDirect controlNetwork-wide viewsSoftware Defined Networking (COMS 6998-8)70Layers of the 4D ArchitectureData Plane:Spatially distributed routers/switchesCan deploy with todays technologyLooking at ways to unify forwarding paradigms across technologiesDecisionDisseminationDiscoveryDataNetwork-level objectivesDirect controlNetwork-wide viewsSoftware Defined Networking (COMS 6998-8)71Advantages of 4DSeparate network logic from distributed systems issuesenables the use of existing distributed systems techniques and protocols to solve non-networking issuesHigher robustnessraises level of abstraction for managing the networkallows operators to focus on specific network-level objectivesBetter securityreduces likelihood of configuration mistakesAccommodating heterogeneityEnable Innovationsonly decision plane needs to be changedSoftware Defined Networking (COMS 6998-8)72Challenges of 4DReducing complexityDramatically simplifying overall system? Or is it just moving complexity?Unavoidable delays to have network-wide view. Is it possible to have a network-wide view sufficiently accurate and stable to manage the network?The logic is centralized in Decision Element (DE) Is it possible to respond to network failures and restore data flow within an acceptable time?DE can be a single point of failure. Attackers can compromise the whole network by controlling DESoftware Defined Networking (COMS 6998-8)73Research Agenda: Decision PlaneAlgorithms to satisfy Network-level objectivesTraffic Engineering: beyond intractable problems?Reachability PoliciesPlanned MaintenanceSpecification of network-level objectives: new language?Coordination between Decision ElementsTo avoid a single point of failure, multiple DEs1) only elected leader sends instructions to all2) independent DEs without coordination: network elements resolves commands from different DEs Hierarchy in Decision PlaneSoftware Defined Networking (COMS 6998-8)74Research Agenda: Dissemination PlaneSeparate control from data logicallysupervisory channel in SONET, optical linksno separation channel for control and data in the InternetHow to achieve robust, efficient connection of DE with routers and switches?floodingspanning-tree protocolssource routingWhen to apply the new logic in data planeeach router applies update ASAPcoordinate update at a pre-specified time: need time synchSoftware Defined Networking (COMS 6998-8)75Research Agenda: Discovery PlaneTodayconsistency between management logic, configuration files, and physical reality is maintained manually!4DBootstrapping with zero pre-configurationAutomatically discovering the identities of devices and the logical/physical relationships between themSupporting cross-layer auto-discovery

Software Defined Networking (COMS 6998-8)76Research Agenda: Data PlaneData plane handles data packets under direct control of the decision planeDecision plane algorithms should vary depending on the forwarding paradigms in data planePacket-forwarding paradigmsLongest-prefix matching (IPv4, IPv6)Exact-match forwarding (Ethernet)Label switching (MPLS, ATM, Frame Relay)Weighted splitting over multiple outgoing links or single out-going link?

Software Defined Networking (COMS 6998-8)774D SummaryFundamental questions to re-design control & management functions for data networksdecision logic blended with protocols abstracts and isolates themuncoordinated, error-prone low-level mechanisms consistent manner by network-level objectivesnetwork operators tune parameters network designers directly controlhuman operators check network-wide views network itself check the info in real-timeSoftware Defined Networking (COMS 6998-8)78Questions?Software Defined Networking (COMS 6998-8)7980RIB-Out shadow tables PrefixesBGP updates (to routers)(points to currently used route for each router) rtr1rtr2rtr3(stores copies of routes)BGP routes PrefixesBGP updates (from egress routers)Global route tableeg1eg2eg3eg1eg2eg3IGP updates(points to routes that use each egress)Egress listsrtr1rtr2RCS data structuresSoftware Defined Networking (COMS 6998-8)80