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Stanford University Software Defined Networks and OpenFlow SDN CIO Summit 2010 Nick McKeown & Guru Parulkar In collaboration with Martin Casado and Scott Shenker And contributions by many others Executive Summary • The network industry is starting to restructure • The trend: “Software Defined Networks” – Separation of control from datapath – Faster evolution of the network • It has started in large data centers • It may spread to WAN, campus, enterprise, home and cellular networks • GENI is putting SDN into hands of researchers 2 What’s the problem? 3 Cellular industry • Recently made transition to IP • Billions of mobile users • Need to securely extract payments and hold users accountable • IP sucks at both, yet hard to change How can they fix IP to meet their needs? 4 Telco Operators • Global IP traffic growing 40-50% per year • End-customer monthly bill remains unchanged • Therefore, CAPEX and OPEX need to reduce 40-50% per Gb/s per year • But in practice, reduces by ~20% per year How can they stay in business? How can they differentiate their service? 5 Trend #1 (Logical) centralization of control 6 Already happening Enterprise WiFi – Set power and channel centrally – Route flows centrally, cache decisions in APs – CAPWAP etc. Telco backbone networks – Calculate routes centrally – Cache routes in routers 7 Experiment: Stanford campus 2006 How hard is it to centrally control all flows? 35,000 users 10,000 new flows/sec 137 network policies 2,000 switches 2,000 switch CPUs How many $400 PCs to centralize all routing and all 137 policies? Controllers Ethernet Switch Ethernet Switch Ethernet Switch Host B Host A Ethernet Switch [Ethane, Sigcomm ‘07] Answer: less than one 10 If you can centralize control, eventually you will. With replication for fault-tolerance and performance scaling. 11 How will the network be structured? 12 The Current Network Routing, management, mobility management, access control, VPNs, … Feature Feature Operating System Specialized Packet Forwarding Hardware Million of lines of source code 5900 RFCs Barrier to entry Billions of gates Bloated Power Hungry Vertically integrated Many complex functions baked into the infrastructure OSPF, BGP, multicast, differentiated services, Traffic Engineering, NAT, firewalls, MPLS, redundant layers, … Looks like the mainframe industry in the 1980s 13 Restructured Network Feature Feature Network OS Feature Feature Operating System Feature Specialized Packet Forwarding Hardware Feature Feature Operating System Feature Specialized Packet Forwarding Hardware Operating System Feature Specialized Packet Forwarding Hardware Feature Operating System Feature Feature Specialized Packet Forwarding Hardware Operating System Specialized Packet Forwarding Hardware 14 Trend #2 Software-Defined Network 15 The “Software-defined Network” 3. Well-defined open API Feature Feature 2. At least one Network OS probably many. Open- and closed-source Network OS 1. Open interface to packet forwarding OpenFlow Packet Forwarding Packet Forwarding Packet Forwarding Packet Forwarding Packet Forwarding 16 OpenFlow Basics Narrow, vendor-agnostic interface to control switches, routers, APs, basestations. 17 Step 1: Separate Control from Datapath Network OS OpenFlow Switch OpenFlow Switch OpenFlow Switch OpenFlow Switch 18 Step 2: Cache flow decisions in datapath “If header = x, send to port 4” Network OS “If header = y, overwrite header with z, send to ports 5,6” “If header = ?, send to me” Flow OpenFlow Table Switch OpenFlow Switch OpenFlow Switch OpenFlow Switch 19 Plumbing Primitives 1. Match arbitrary bits in headers: Data Header e.g. Match: 1000x01xx0101001x – Match on any header; or user-defined header – Allows any flow granularity 2. Actions: – Forward to port(s), drop, send to controller – Overwrite header with mask, push or pop – Forward at specific bit-rate 20 Ethernet Switch/Router Control Path (Software) Data Path (Hardware) OpenFlow Controller OpenFlow Protocol (SSL) Control Path OpenFlow Data Path (Hardware) The “Software Defined Network” 3. Well-defined open API Feature Feature 2. At least one Network OS probably many. Open- and closed-source Network OS 1. Open interface to packet forwarding Packet Forwarding Packet Forwarding Packet Forwarding Packet Forwarding Packet Forwarding 24 Network OS Several commercial Network OS in development – Commercial deployments late 2010 Research – Research community mostly uses NOX – Open-source available at: http://noxrepo.org – Expect new research OS’s late 2010 25 Software Defined Networks in Data Centers 26 Example: New Data Center Cost Control 200,000 servers Fanout of 20 10,000 switches $5k vendor switch = $50M $1k commodity switch = $10M 1.More flexible control 2.Quickly improve and innovate 3.Enables “cloud networking” Savings in 10 data centers = $400M Several large data centers will use SDN. Data Center Networks Existing Solutions – Tend to increase hardware complexity – Unable to cope with virtualization and multitenancy Software Defined Network – OpenFlow-enabled vSwitch – Open vSwitch http://openvswitch.org – Network optimized for data center owner – Several commercial products under development 28 Software Defined Networks on College Campuses 29 What we are doing at Stanford 1. Defining the OpenFlow Spec – Check out http://OpenFlow.org – Open weekly meetings at Stanford 2. Enabling researchers to innovate – Add OpenFlow to commercial switches, APs, … – Deploy on college campuses – “Slice” network to allow many experiments 30 Isolated “slices” Feature Feature Feature Feature Network Operating System 1 Network Operating System 2 Network Operating System 3 Network Operating System 4 OpenFlow Virtualization or “Slicing” Layer OpenFlow Packet Forwarding Packet Forwarding Packet Forwarding Packet Forwarding Packet Forwarding Some research examples 32 FlowVisor Creates Virtual Networks OpenPipes Experiment OpenFlow Wireless Experiment PlugNServe Load-balancer OpenFlow Protocol OpenFlow Switch OpenFlow Switch OpenFlow Protocol OpenFlow Switch FlowVisor Policy #1 Multiple, isolated slices in the same physical network Demo Infrastructure with Slicing Application-specific Load-balancing Goal: Minimize http response time over campus network Approach: Route over path to jointly minimize <path latency, server latency> “Pick path & server” Internet LoadBalancer Network OS OpenFlow Switch OpenFlow Switch OpenFlow Switch OpenFlow Switch OpenFlow Switch Intercontinental VM Migration Moved a VM from Stanford to Japan without changing its IP. VM hosted a video game server with active network connections. Converging Packet and Circuit Networks Goal: Common control plane for “Layer 3” and “Layer 1” networks Approach: Add OpenFlow to all switches; use common network OS Feature Feature NOX OpenFlow Protocol OpenFlow Protocol WDM Switch IP Router TDM Switch WDM Switch IP Router [Supercomputing 2009 Demo] [OFC 2010] ElasticTree Goal: Reduce energy usage in data center networks Approach: 1. Reroute traffic 2. Shut off links and switches to reduce power “Pick paths” DC Manager Network OS [NSDI 2010] ElasticTree Goal: Reduce energy usage in data center networks Approach: 1. Reroute traffic 2. Shut off links and switches to reduce power X X X “Pick paths” DC Manager X Network OS X [NSDI 2010] Executive Summary • The network industry is starting to restructure • The trend: “Software Defined Networks” – Separation of control from datapath – Faster evolution of the network • It has started in large data centers • It may spread to WAN, campus, enterprise, home and cellular networks • GENI is putting SDN into hands of researchers 40 Thank you 41