Open Source Network:

Software-Defined Networking (SDN)

and OpenFlow

Insop Song, Ericsson

LinuxCon North America, Aug. 2012, San Diego CA

Objectives

• Overview of OpenFlow

• Overview of Software Defined Networking

(SDN)

Disclaimer

• This presentation represents the view of the

author and does not necessarily represent the

view of Ericsson

• OpenFlow is an invention from network

researchers Stanford and UCB

Overview of network equipment

• Network equipment

– Layer 2 Ethernet switches, IP routers

Features

Forwarding H/W: ASICs/FPGAs or Merchant silicon chips

Operating system

Feature Feature. . .Feature

Data plane

• Hardware packet forwarding path– Line rate forward packets output ports

– Adding tags, Modifying packets

– Drop packets

– Forward packets to CPU

– Collect traffic statistics

– Programmed by control plane or manual configuration (management)

L2 table (MAC + Vlan) L3 table (IP) ACL, QoS

Switch/Router

Packets in

Packet out

Packet out

Control plane

• Control plane

– Handling protocol packets at CPU

– Track topology changes

– Handles protocol and routes

– Updates hardware L2/L3 forwarding tables & ACL

ASICs/FPGAs or Merchant silicon chips

Protocol S/WCPU

Control

Packets in

1. Packet forward to CPU2. Table config

Network configuration

• Distributed dynamic routing running on heterogeneous environment

• Protocol based distributed state management– STP, OSPF, BGP

• Manual configuration– Policies, SLA, VLAN

Router

Router

Server

Server

Server

Router

switch

switch

switch

Forwarding h/w

OS

feature

Network equipment…

• Mastering complexity …

– No well defined API for control packet handling

– No generalized API for data path state

– Tight vertical integration

– Complicated and lack of abstraction

– Distributed state management is hard

– Lack of global and consistent view of network,

hard to manage overall network

Solutions

• Generalize data plane

– Flexible flow table management

– Decouple data and control planes

– API for handling control packets

• Decouple distributed model from physical topology

– Take out the control logic from the network equipment

Flow table

Simple packet forwarding hardware

Flow table

Generalized API

Packet

forwarding

hardware

Controller(s)

Packet

forwarding

hardware

Packet

forwarding

hardware

OpenFlow

• Started from academia as a way to test experimental protocol on a real network

• Identify flexible common set of functions for flow table

• Provides open protocol to program flow table through secure channel

Flow table

Simple packet forwarding hardware

Flow table

OpenFlow protocol

SSL/TCP

OpenFlow Network

Controller

OpenFlow

• Logically centralized controller

• Generalized data plane API using Flow table

Packet

forwarding

hardware

Network OS

Packet

forwarding

hardware

Packet

forwarding

hardware

“If header == a, send to port 10”“if header == b, modify header with c, and send to port 11”“if header == ?, then send to controller”

Flow

table(s)Flow

table(s)

Flow

table(s)

Control program 1 Control program 2

OpenFlow

• Flow table(s)

Match Action Status

PortDst

Mac

Src

Mac

Eth

typeVlan Src IP Dst IP

TCP src

port

TCP dst

port…

Pop/Push tags

Decrement TTL

Set fields

Apply QoS

Forward packets

counter

OpenFlow

• Example of Flow table

Src MAC Dst MAC Src IP Dst IP TCP sport … Action Count

* 10:1f:* * * * * Port 2 100

* * * 1.2.3.4 * * Port 3 200

* * * * 22 drop 300

00:20:.. 00:1f:.. 1.2.3.4 5.6.7.8 1234 Port4 400

* * * * * * Controller 500

OpenFlow Specification

Version Summary

1.0 Initial version

1.1 Multi-table pipeline processing, MPLS, QinQ

1.2 IPv6, Extensible Match (OXM) and additional extensibility

1.3 QoS and PBB additions

Decouple Data and Control planes

• Easier to implement new ideas

– Remove dependencies between vendor SDK

• Easier to test and maintain software

– Centralized programming and more abstraction

• Easier interoperability between vendors

– Using standard API (programing flow and receiving control packets)

• More powerful computing for control logic network management

– Network control could be off-loaded to servers

Software-Defined Networking

• Traditional network

• Closed box, closed API

• Distributed protocol

Packet

forwarding

hardware

Network OS

Packet

forwarding

hardware

Packet

forwarding

hardware

Flow

table(s)Flow

table(s)

Flow

table(s)

Feature Feature

Forwarding h/w

OS

feature

Forwarding h/w

OS

feature

Forwarding h/w

OS

feature

• SDN

• Open standard API

• Logically centralized

Well-defined

API

OpenFlow

Centralized controller

• Less system overhead on the network node

– Minimize protocol packets for distributed protocol

• Network topology

– Easier to have consistent global view of the

network

• Management

– Easier to mange programmable network

SDN Use cases

• Data center

– SDN facilitates network virtualization

– Google, Dell, Yahoo, Facefook, Amazon

• Campus

– Enable IT to apply consistent policies in wired and wireless network

– Stanford and many other universities

• Cloud

– Allows flexible network allocation

Academia and industry

• Close collaboration between university and

industry

• Open Networking Foundation (ONF)

– Standard body by 70+ (growing)

• Many companies participating

– From large companies to startups

– From chip vendors to service integrators

– Google, Cisco, HP, NEC, Ericsson, IBM, Juniper

– VMWare (Nicira), Big switch, and more

OpenFlow switches

• Current OpenFlow supporting switches

– Growing…, so check with your vendors

– Juniper, HP, NEC, NetGear, Ciena, Pronto

• Many companies are prototyping OpenFlow

switches

• Google made their own OpenFlow switches

OpenFlow network controllers

Lang License Original author note

OpenFlow

reference

C OpenFlow License Stanford/Nicira Reference design

NOX C++ GPL Nicira Nox classic C++/Python

POX Python GPL http://www.noxrepo.

org

Nox Python version

Beacon Java GPL Stanford Run time modular, web

UI

Floodlight Java Apache Big switch Easy to build and set up

Trema Ruby, C GPL NEC Including emulator, test

framework

RouteFlow C Apache CPqD, Brazil OpenFlow with Quagga

stack

How to experiment

• Mininet

– Allows to create hundreds of nodes on a single PC

– OpenFlow tutorial is based on Mininet

Open source

• Open vSwitch

– Software switch supports OpenFlow

– Upstream from 3.3 kernel

• Various network controller are open source

• Open API

• Openness is one of the key reasons for

SDN/OpenFlow success

Questions?

• Scalability

– Is it scalable?

• Reliability

– High availability

• Security

– Security risk on the centralized controller(s)

• Interoperability

– Co-existing with existing equipment and neighboring domain

Summary

• OpenFlow

– Enabling generalized open API for configuring flow

table

– Clean separation between data and forwarding

planes

• SDN

– Allowing us to define the right abstractions

– Network virtualization

– Very successful so far, more real changes to come..

– The future of networking?

References:

1. The Future of Networking, and the Past of Protocols : Scott Shenker

2. An attempt to motivate and clarify SDN : Scott Shenker

3. Making SDNs Work - Nick McKeown

4. Origins and Evolution of OpenFlow/SDN - Martin Casado

5. OpenFlow @ Google - Urs Hoelzle, Google

6. Opening Up Your Network to Cloud Innovation with SDN: Guido Appenzeller

7. Software Defined Networking is an Architecture Not a Protocol , David Meyer, Cisco

8. SDN and OpenFlow A Tutorial

9. OpenFlow Switch Specification 1.3

10. Software-Defined Networking: The New Norm for Networks: ONF White Paper

• Thank you

• Question?