Software Defined Networks and OpenFlow SDN CIO Summit 2010 Nick McKeown & Guru Parulkar Stanford University 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 How hard is it to centrally control all flows? ,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 Host A Host B [Ethane, Sigcomm ‘07] Ethernet Switch Ethernet Switch Ethernet Switch Ethernet Switch Ethernet Switch Ethernet Switch Ethernet Switch Ethernet Switch

Answer: 10 less than one

If you can centralize control, eventually you will. With replication for fault-tolerance and performance scaling. 11

How will the network be structured? 12

Million of lines of source code 5900 RFCsBarrier to entry Billions of gates BloatedPower 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 The Current Network Specialized Packet Forwarding Hardware Operating System Operating System Feature Routing, management, mobility management, access control, VPNs, … 13

Specialized Packet Forwarding Hardware Feature Specialized Packet Forwarding Hardware Operating System Operating System Operating System Operating System Operating System Operating System Operating System Operating System Operating System Operating System Network OS Feature Restructured Network 14

Trend #2 Software-Defined Network 15

Feature Network OS 1. Open interface to packet forwarding 3. Well-defined open API 2. At least one Network OS probably many. Open- and closed-source The “Software-defined Network” OpenFlow 16 Packet Forwarding Packet Forwarding Packet Forwarding Packet Forwarding Packet Forwarding Packet Forwarding Packet Forwarding Packet Forwarding Packet Forwarding Packet Forwarding

OpenFlow Basics Narrow, vendor-agnostic interface to control switches, routers, APs, basestations. 17

Network OS Step 1: Separate Control from Datapath 18 OpenFlow Switch OpenFlow Switch OpenFlow Switch OpenFlow Switch

Step 2: Cache flow decisions in datapath “If header = x, send to port 4” “If header = ?, send to me” “If header = y, overwrite header with z, send to ports 5,6” 19 OpenFlow Switch OpenFlow Switch OpenFlow Switch OpenFlow Switch Flow Table Flow Table Network OS

Plumbing Primitives 1.Match arbitrary bits in headers: – 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 Header Data e.g. Match: 1000x01xx x

Ethernet Switch/Router

Data Path (Hardware) Control Path Control Path (Software)

Data Path (Hardware) Control Path OpenFlow OpenFlow Controller OpenFlow Protocol (SSL)

Feature Network OS 1. Open interface to packet forwarding 3. Well-defined open API 2. At least one Network OS probably many. Open- and closed-source The “Software Defined Network” 24 Packet Forwarding Packet Forwarding Packet Forwarding Packet Forwarding Packet Forwarding Packet Forwarding Packet Forwarding Packet Forwarding Packet Forwarding Packet Forwarding

Network OS Several commercial Network OS in development – Commercial deployments late 2010 Research – Research community mostly uses NOX – Open-source available at: – Expect new research OS’s late

Software Defined Networks in Data Centers 26

Example: New Data Center Cost 200,000 servers Fanout of 20  10,000 switches $5k vendor switch = $50M $1k commodity switch = $10M Savings in 10 data centers = $400M Control 1.More flexible control 2.Quickly improve and innovate 3.Enables “cloud networking” Several large data centers will use SDN.

Data Center Networks Existing Solutions – Tend to increase hardware complexity – Unable to cope with virtualization and multi- tenancy Software Defined Network – OpenFlow-enabled vSwitch – Open vSwitch – 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 – 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

OpenFlow Virtualization or “Slicing” Layer Isolated “slices” Packet Forwarding Packet Forwarding Packet Forwarding Packet Forwarding Packet Forwarding Packet Forwarding Packet Forwarding Packet Forwarding Network Operating System 1 Network Operating System 2 Network Operating System 3 Network Operating System 4 Feature OpenFlow Feature Packet Forwarding Packet Forwarding

Some research examples 32

FlowVisor Creates Virtual Networks OpenFlow Protocol FlowVisor OpenPipes Experiment OpenFlow Wireless Experiment OpenFlow Protocol PlugNServe Load-balancer Policy #1 Multiple, isolated slices in the same physical network OpenFlow Switch OpenFlow Switch OpenFlow Switch

Demo Infrastructure with Slicing

Application-specific Load-balancing OpenFlow Switch OpenFlow Switch OpenFlow Switch OpenFlow Switch Internet OpenFlow Switch Goal: Minimize http response time over campus network Approach: Route over path to jointly minimize Network OS Load- Balancer “Pick path & server”

Intercontinental VM Migration Moved a VM from Stanford to Japan without changing its IP. VM hosted a video game server with active network connections.

Feature NOX Converging Packet and Circuit Networks IP Router IP Router TDM Switch TDM Switch WDM Switch WDM Switch WDM Switch WDM Switch IP Router IP Router Goal: Common control plane for “Layer 3” and “Layer 1” networks Approach: Add OpenFlow to all switches; use common network OS OpenFlow Protocol OpenFlow Protocol [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 [NSDI 2010] Network OS DC Manager DC Manager “Pick paths”

ElasticTree Goal: Reduce energy usage in data center networks Approach: 1.Reroute traffic 2.Shut off links and switches to reduce power [NSDI 2010]XX X X X Network OS DC Manager DC Manager “Pick paths”

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