Software Defined-Networking

Network Policies

• Access control: reachability– Alice can not send packets to Bob

• Application classification– Place video traffic in the gold queue

Network Management: Past

Networking Yesterday

• Data plane– Determines how to forward a packet– Looks up the forwarding table to determine output port for a packet

• Control plane– Determines how to populate the forwarding tables– Translate user commands into hardware

• ACLs, MPLS

– Runs a bunch of routing protocols• IGPs: OSPF, IS-IS, RIP, & EGPs: BGP

OSPF

MPLS

IP

BGP

VLAN10.10.2.10 1

2.3.4.23 3

Prefix Port

23 145 3

MPLS Label Path

Networking Yesterday

• Control + Data-plane on each device– Network is a Distributed systems– Built to avoid failure (ArpaNet)

• A network is supported by an infinite number of protocols– New protocols developed to support new functionality– Takes time to standardize and to change the hardware

• Think: writing a distributed program in Perl– Error prone (Over 50% of errors caused by misconfig)– Time consuming

• IT Operators are the most costly portion of IT• Takes up to 6 months for ISPs to roll out services for new costumers • Very difficult to add new functionality into the network

Networking Evolution• SDN is nothing new

• Circuit switching in Telephone networks

• RCP – Centralize control plane– Configure protocols rather than control plane

• 4D – clean-slate architecture

• Ethane/Sane – Centralize control plane– Forces switches do encrypt/decrypt each packet– No standardized interface

Requirements for SDN• Operate without Guarantees

– Need abstraction for distributed state– Want to deal with information without worrying about the fact that the state is from a

distribution– Logically Centralized

• Compute configuration of each device– Need abstraction that simplifies configuration– Want to specify your intent desired goal; the what– NOT: how to do it.

• Operate within given network-level protocol– Need abstraction for forwarding model– Hide details about hardware specifics– No need to worry about he exact harware

OpenFlow Protocol

Network Operating

System

Network Operating

System

Enter Software Defined Networking:Separation of concerns

– Network operator • Specify behavior on a model • Behavior == network policies

– Network runtime • Provides abstract view of the network• Maps abstract view to global view• Function of the types of network policies to be supported

– Network Operation System • Maps global view to physical view• Translate abstract commands to device configuration• Device interface: forwarding abstractions

Thinks to think about

• Distributed state abstraction– What is the right central view

• Configuration abstraction– What should the interface to the Switch hardware

look like

• Forwarding abstraction– What to expose to the network operator

SDN NetworkNetwork ControllerNetwork Operation System

OpenFlow Protocol

• Message between controller and switches– Synchronous • Stats, Flow-mods

– Asynchronous • Packet-in

• Abstract hardware details• Allows direct control over forwarding table

10.2.3.4:10.2.3.3 Fwd Port 1

A2:e3:f1:ba:ea:23:* Drop

Match Action

The SDN Stack

Controller

13

NetFPGASoftware Ref. Switch

Broadcom Ref. Switch

OpenWRT PCEngine WiFi AP

Commercial Switches

OpenFlowSwitchesOpen vSwitch

HP, NEC, Pronto, Juniper.. and many more

The SDN Stack

ControllerNOX

14

NetFPGASoftware Ref. Switch

Broadcom Ref. Switch

OpenWRT PCEngine WiFi AP

Commercial Switches

OpenFlowSwitches

…

Open vSwitch

HP, NEC, Pronto, Juniper.. and many more

Beacon Trema Maestro

15

ControllersName Lang Original Author Notes

OpenFlow Reference

C Stanford/Nicira not designed for extensibility

NOX Python, C++ Nicira actively developed

Beacon Java David Erickson (Stanford) runtime modular, web UI framework, regression test framework

Maestro Java Zheng Cai (Rice)Trema Ruby, C NEC includes emulator, regression test

framework

RouteFlow ? CPqD (Brazil) virtual IP routing as a service

POX Python

Floodlight Java BigSwitch, based on Beacon

Too many to easily keep track of…http://yuba.stanford.edu/~casado/of-sw.html

The SDN Stack

ControllerNOX

SlicingSoftwareFlowVisor

FlowVisorConsole

16

NetFPGASoftware Ref. Switch

Broadcom Ref. Switch

OpenWRT PCEngine WiFi AP

Commercial Switches

OpenFlowSwitches

…

Open vSwitch

HP, NEC, Pronto, Juniper.. and many more

Beacon Trema Maestro

FlowVisor Creates Virtual Networks

OpenFlow Switch

OpenFlow Switch

OpenFlow Switch

OpenFlowProtocol

FlowVisor

Simple switch CloudNaaS

OpenFlowProtocol

Stratos

Reservations

FlowVisor slices OpenFlow networks, creating multiple isolated and programmable

logical networks on the same physical topology.

Each application runs in an isolated slice of the network.

17

The SDN Stack

ControllerNOX

SlicingSoftwareFlowVisor

FlowVisorConsole

18

ApplicationsCloudNaaSSimple Switch …Stratos

NetFPGASoftware Ref. Switch

Broadcom Ref. Switch

OpenWRT PCEngine WiFi AP

Commercial Switches

OpenFlowSwitches

…

Open vSwitch

HP, NEC, Pronto, Juniper.. and many more

Beacon Trema Maestro

The Dark Side of SDN• “Logically” centralized controller

– Scalability– Fault tolerance

• Flowtable entries– Limited number of TCAM entries– Can only support so many TCAM entries

• SDN Abstractions– Currently one set of abstraction for all devices– Edge and Core fundamentally different– Switches Versus Middleboxes