Download Specialized Packet Forwarding Hardware

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
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What’s the problem?
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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?
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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?
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Trend #1
(Logical) centralization of control
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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
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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
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If you can centralize control,
eventually you will.
With replication for
fault-tolerance and performance scaling.
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How will the
network be structured?
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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
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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
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Trend #2
Software-Defined Network
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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
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OpenFlow Basics
Narrow, vendor-agnostic interface to
control switches, routers, APs, basestations.
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Step 1:
Separate Control from Datapath
Network OS
OpenFlow
Switch
OpenFlow
Switch
OpenFlow
Switch
OpenFlow
Switch
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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
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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
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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
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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
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Software Defined Networks
in Data Centers
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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
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Software Defined Networks
on College Campuses
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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
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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
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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
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Thank you
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