OpenFlow : Enabling Innovation in Campus Networks

THALLAPAKA MAHENDRA REDDY

Email : thallapakamahendrareddy@gmail.com

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Contents• Introduction• The Need For Programmable Network• Internet Closed for Innovations• OpenFlow

– Goals– Concepts– Architecture– Flow Table Structure– Controller

• Summary• Conclusion• Reference

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Introduction

• It is based on an Ethernet switch, with an internal flow-table, and a standard-ized interface to add and remove flow entries.

• OpenFlow could serve as a useful cam-pus component in proposed large-scale testbeds like GENI.

The Need For Programmable Net-work

• Today, there is almost no practical way to experiment with new network protocols in sufficiently realistic setting to gain the confidence needed for their widespread deploy-ment.

• These programmable networks call for programmable switches and routers that can process packets for multiple isolated experimental networks simultaneously.

• Virtualized programmable networks could lower the barrier to entry for new ideas, increasing the rate of innovation in the network infrastructure.

OpenFlow is a specification that is an initial attempt to meet the goal

high-performance and low-cost imple-mentations.

Capable of supporting a broad range of research.

Assured to isolate experimental traffic from production traffic.

Consistent with vendors’ need for closed platforms.

Innovations in Legacy Internet

• Experiments we’d like to do new– Mobility management– Network-wide energy management– New naming/addressing schemes– Network access control

• Problem with our network– Paths are fixed– IP-only– Addresses dictated by DNS, DHCP, etc– No means to add our own processing

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Why Internet Closed for Innovations?

• Commercial Vendor won’t open software and hardware development environment– Complexity of support– Market protection and barrier to entry

• Hard to build my own– Prototypes are unstable– Software only : Too slow– Hardware/Software : Fanout too small

(need>100 ports for wiring closet)7/17

Experimenter’s Dream(Vendor’s Nightmare)

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StandardNetwork

Processing

StandardNetwork

Processinghwsw Experimenter writes

experimental codeon switch/router

User-defined

Processing

User-defined

Processing

StandardNetwork

Processing

StandardNetwork

Processing

OpenFlow’s Goal

• Put an open platform– researchers/students to test new ideas at scale

through production networks– without requiring vendors to expose internal

workings• Bring Future Internet to legacy Internet• An open development environment for all re-

searchers(e.g. Linux, Verilog, etc)

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OpenFlow Concept

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Ethernet SwitchControl Path (Software)

Data Path (Hardware)

Control Path

Data Path (Hardware)

OpenFlow

OpenFlow Controller

OpenFlow Protocol (SSL/TCP)

Using OpenFlow

• If someone want to try their protocol in a net-work of OpenFlow Switches, without changing any end-host software.

The protocol will run in a controller; each time

a new application flow starts that protocol

picks a route through a series of OpenFlow

Switch,and adds a flow entry in each switch

along the path.

Using OpenFlow(2)

• If someone is testing a new protocol in a network used by lots of other people. It will have two additional properties：1. Packets belonging to users other than the researcher

should be routed using a standard and tested routing protocol running in the switch or router from a “name-brand” vendor.

2. the researcher should only be able to add flow entries for his traffic, or for any traffic his network administra-tor has allowed her to control.

Using Openflow(3)Example 1 ： Network Management and access Control•an OpenFlow Switch can be thought of as a generalization of Ethane’s datapath switch. The controller checks a new flow against a set of rules , and associates packets with their senders by managing all the bindings between names and ad-dresses.Example 2： VLANs•The simplest approach is to statically declare a set of flows which specify the ports accessible by traffic on a given VLAN ID. Example 3: Mobile wireless VOIP•In the experiment VOIP clients establish a new connection over the OpenFlow-enabled network. A controller is imple-mented to track the location of clients, re-routing connections as users move through the network (by reprogramming the Flow Tables ), allowing seamless handoff from one access point to another.

Using OpenFlow(4)Example 4: A non-IP network•OpenFlow doesn’t require packets to be of any one format — so long as the Flow Table is able to match on the packet header. This would allow experiments using new naming, ad-dressing and routing schemes.Example 5: Processing packets rather than flows1.To force all of a flow’s packets to pass through a controller.2.To route them to a programmable switch that does packet processing

OpenFlow Network Architecture

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Controller

OpenFlow Switch

FlowTableFlowTable

SecureChannelSecure

Channel

PCOpenFlow

Protocol

SSL

hw

sw

OpenFlow Switch specification

Operation Step

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Controller

PC

OpenFlowSwitch

OpenFlowSwitch

OpenFlowSwitch

OpenFlowSwitch

New func-tion!

If header = x, send to port 4If header =y, overwrite header with z,

send to ports 5,6If header = ?, send to me

FlowTa-ble

FlowTa-ble

FlowTa-ble

FlowTa-ble

Packet Processing

• OpenFlow SW’s Packet Processing– Search a matched entry of flow table with arriving

packet’s information

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Packetin from

NetworkFlow lookup

Send to securechannel

Apply actions

No match

Match

Flow Table Structure

• Exploit flow table in switches, routers, and chipsets

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Flow Table Entry

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SwitchPort

MACsrc

MACdst

Ethtype

VLANID

IPSrc

IPDst

IPProt

TCPsport

TCPdport

Rule Action Stats

1. Forward packet to port(s)2. Encapsulate and forward to controller3. Drop packet4. Send to normal processing pipeline

+ mask

Packet + byte counters

Flow Table Entry Examples(OpenFlow is Backward Compatible)

• Ethernet Switching

• IP Routing

• Application Firewall

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SwitchPort

MACsrc

MACdst

Ethtype

VLANID

IPSrc

IPDst

IPProt

TCPsport

TCPdport Action

* * 00:1F:. * * * * * * * port6

SwitchPort

MACsrc

MACdst

Ethtype

VLANID

IPSrc

IPDst

IPProt

TCPsport

TCPdport Action

* * * * * * 5.6.7.8 * * * port6

SwitchPort

MACsrc

MACdst

Ethtype

VLANID

IPSrc

IPDst

IPProt

TCPsport

TCPdport Action

* * * * * * * * * 22 drop

Flow Table Entry Examples(OpenFlow allows layers to be combined)

• Flow Switching

• VLAN + App

• Port + Ethernet + IP

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SwitchPort

MACsrc

MACdst

Ethtype

VLANID

IPSrc

IPDst

IPProt

TCPsport

TCPdport Action

port3 00:2E:.. 00:1F:. 0800 vlan1 1.2.3.4 5.6.7.8 4 17264 80 port6

SwitchPort

MACsrc

MACdst

Ethtype

VLANID

IPSrc

IPDst

IPProt

TCPsport

TCPdport Action

* * * * vlan1 * * * * 80 port6

SwitchPort

MACsrc

MACdst

Ethtype

VLANID

IPSrc

IPDst

IPProt

TCPsport

TCPdport Action

port3 00:2E:.. * 0800 * * 5.6.7.8 4 * 22 drop

OpenFlow Controller

• Centralized Intelligential agency for entire OpenFlow network

• NOX is an open-source OpenFlow Controller• Researchers can insert their software code

into NOX controller for testing their idea

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Nox Controller

OpenFlow SwitchOpenFlow Switch OpenFlow Switch

OpenFlow Hardware (Switches)

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• NEC

• HP

• Pronto

Summary

• OpenFlow– Standard way to control flow-tables in commercial

switches and routers– Put an open platform– An open development environment for all re-

searcher– Test Environment for Future Internet Technologies

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Conclusion

• We believe that OpenFlow is a prag-matic compromise that allows re-searchers to run experiments on het-erogeneous switches and routers in a uniform way, without the need for vendors to expose the internal work-ings of their products, or researchers to write vendor-specific control soft-ware.

Reference

1. N. McKeown, T. Anderson, H. Balakrishnan, G. Parulkar, L. Peterson, J. Rexford, S. Shenker, and J. Turner, “OpenFlow: Enabling Innovation in Campus Networks,” ACM SIGCOMM Computer Communication Review, vol. 38, no. 2, p. 6, 2008.

2. “OpenFlow Switch Specification, Version 1.0.0,” Decem-ber 2009.