SDN

Software Defined Networking (SDN)

Teng Chee Seng

ITE College West, Institute of Technical Education Singapore

Software Defined Networking - Introduction 1

Software Defined Networking

• Objective: share with you some insight into SDN as a new trend in network provisioning

• Starting to see some significant deployments appearing – Currently typically within data centres – One example is Google , Vmware

• Key takeaway from this lecture is the principle behind SDN, and how it can be implemented using OpenFlow

• At the end of the slide deck we give you pointers to an

example that you can try later using Mininet – SDN using open source components


Software Defined Networking

• One part of a number of interesting emerging trends

• Software Defined Networking (SDN)

• Network Function Virtualisation (NFV) – Network as a Service (NaaS) – One of many *aaS services

• Service Function Chaining (SFC)

– Directing traffic through virtualised services • Firewall, NAC, DDoS mitigation, IDS, …

– New IETF SFC WG just formed – very popular


Existing switching / routing

• Switching and routing today uses dedicated hardware – Commonly combined in one device

• Routers:

– Control plane – routing protocol, e.g. OSPF, BGP – creates the Routing Information Base (RIB)

– Data plane – Forwarding Information Base (FIB), written by control plane, from RIB information it holds

– Management plane – via ssh, via SNMP

• Switches:

– Dumb devices, optimised for fast layer 2 switching – Some additional capability, e.g. ACLs, DHCP snooping, …


Key SDN concepts

• Separation of control and data plane • Centralising network ‘intelligence’

– Through one or more controller device(s)

• Enabling a ‘programmable’ network – Through a control protocol, running between the controller and the

underlying network devices – e.g. using OpenFlow as the control protocol

• Highly dynamic – Can be per-flow, on demand

• Rapid provisioning • Rapid innovation

– Potentially no need to wait for new vendor features – In principle, can empower network owners


SDN drivers

• Changing traffic patterns – e.g. emerging data centre requirements – Need elasticity in services – Be able to meet peak demand; ‘big data’, peak hours – But don’t pay for capacity in quiet periods

• Abstraction of services from hardware

– Firewalls, IDS, … – Need to be able to control traffic paths

• We have seen compute and storage functions virtualised

– SDN is doing the equivalent for the network – One part of a bigger network function virtualisation picture


Challenges

• SDN might provide answers for – Complexity

• Devices have many protocols working in isolation

• A resulting tendency for networks to be static

– Consistency (across a network) • Simpler devices, single logical control point

– Scalability • With flexibility

– Vendor independence • Through generic interfaces to underlying functions

• Underlying equipment interoperable, e.g. via OpenFlow


Manageability

Flexibility

Scalability

Robustness

SDN

ad hoc

low

highest

high

Traditional

IGP, tunnelling (RSVP-TE)

by design

high

low

low

Challenges

SDN architecture – high level


OpenFlow

• OpenFlow is one of many ways to implement a SDN – Origins in Stanford and Berkeley – Open interface to packet forwarding – Provides forwarding abstraction

• Two parts:

– Control protocol – Configuration


The OpenFlow instruction set

• OpenFlow provides a “Match – Action” model • Instructions can be programmed dynamically

– On a per-flow basis, if required

• Allows a controller to populate a device flow table – e.g. “If see this header, send to port N” – “If see header like this, rewrite that part” – “If see this, drop the packet” – “Forward packets matching this a this bit rate”

• Default action is usually to send packet to controller • Provides an abstraction of how all forwarding works today,

as a set of “match – action” instructions • Currently at OpenFlow version 1.4, or OF1.4


Match – Action - Counters


Examples


Programming the network

• The ‘intelligence’ lies with the controller • Can implement whatever algorithms you like in the controller for

provisioning the devices – This in principle allows innovation – Could develop own load-balancing algorithms per application – Can’t do this with vendor-specific routers/switches

• Many open source controllers available – Mininet example later uses a modified NOX controller – Can rapidly prototype using mininet

• Strategies – Can prepopulate the flow table

• Might mean some rules/instructions never used

– Can program on the fly • Will mean some amount of flow creation latency


Example: video streaming


Standards development

• To be interoperable, we still need standards • Open Networking Foundation (ONF)

– Defining OpenFlow – Implemented on switches, routers, wireless APs, … – https://www.opennetworking.org/

• Internet Engineering Task Force (IETF) – SDN RG, i2rs WG, SFC WG, … – http://www.ietf.org

• European Telecommunications Standards Institute (ETSI) – Network Function Virtualisation (NFV) – http://www.etsi.org/technologies-clusters/technologies/nfv

• …


https://www.opennetworking.org/

http://www.ietf.org

http://www.etsi.org/technologies-clusters/technologies/nfv



SDN use cases

• SDN is being proposed for many scenarios, e.g.: – Data centres, cloud computing, campus networks,

home networks, cellular access networks, …

• And for many use cases, e.g.: – Load balancing, enabling QoS, enforcing security

policies, IPv6 transition, DDoS mitigation, device quarantining, …

• Growing vendor support: – Some 15 vendors of OpenFlow switches and routers – A growing number of software controllers


Example: OFERTIE

• ECS is part of a European research project called OFERTIE – http://www.ofertie.org/

• Applying SDN / OpenFlow to real-time interactive online applications (ROIAs) – Collaborative 3D editing software

– Multiplayer gaming

• Allows analysis of use cases – Within a data centre (hosting provider, “server lag”)

– Between ISPs (end user access networks)


http://www.ofertie.org/

OFERTIE: ROIAs

• OFERTIE’s target application domain is Real-Time Online Interactive Applications (ROIAs) and their challenging network demands

• Example Application Scenarios: – Collaborative real-time world editor – Large-scale multiplayer online games

• Characteristics include: – High level of interactivity and update rates – Dynamically changing game situations – Network requirements change dynamically – Variable player loads over time – Impact of packet loss and latency on QoE will

depend on what player is doing


Content (assets and artwork) by courtesy of PrävEM research group of the University of Applied Sciences Mittweida.

OFERTIE: Network QoS in ROIAs

• Specification of a novel API that allows ROIA applications to specify their dynamic network requirements and to meet them using SDN technology

• Improve network utilisation by allowing applications to signal type of traffic

• The API frees ROIA developers from specifying detailed, low-level network metrics


OFERTIE: Classes of data transfer

• ROIA data transfers can be classified into various categories:

• Game updates / State synchronisaton – Depends on number of players, proximity, and their activities

• State transfer/migration – e.g. need to migrate ten players (and their data) in 10 seconds – Network Control Layer can feed back to application on path availability

• Asset transfer (upload or download) – e.g. a 2MB asset in 1 minute, or 50MB in 30 seconds

• If the application developer can express these requirements, the

Network Control Layer can make better decisions about provisioning the flows


OFERTIE: Network Control Layer


SDN future

• SDN promises a lot – The network abstraction is very appealing

• The OpenFlow specification hardening – Vendors now shipping OF1.4 support (but 1.51 now out!) – Lots of support out there

• Deploying SDN is a big challenge • It can be deployed incrementally • Examples already within data centres

– e.g. Google, Facebook

• Bigger challenge is end-to-end – Requires inter-ISP/site orchestration


Mininet SDN example

• If you’d like to get a feel for SDN in action…

• Grab mininet

– http://mininet.org/download/

• Example is available via github

– https://github.com/drn05r/ofsoftswitch13-testing

– Wiki contains a walkthrough and example exercises

– Uses NOX OpenFlow 1.4 controller

– Includes OpenFlow 1.4 tutorial

– Uses IPv4, but IPv6 is also supported in latest OF specs


http://mininet.org/download/

https://github.com/drn05r/ofsoftswitch13-testing



Links

• Open Networking Foundation (ONF) – https://www.opennetworking.org/

• Mininet – http://mininet.org/

• Early OpenFlow paper (2008): – http://archive.openflow.org/documents/openflow-wp-latest.pdf

• SDN white paper (2012): – https://www.opennetworking.org/images/stories/downloads/sdn-resources/white-

papers/wp-sdn-newnorm.pdf

• OFELIA presentation – http://www.fp7-ofelia.eu/assets/Publications-and-Presentations/SDN-The-Next-Wave-of-

Networking.pdf

• Coursera – https://www.coursera.org/course/sdn

• Google – http://googlecloudplatform.blogspot.co.uk/2014/04/enter-andromeda-zone-google-cloud-

platforms-latest-networking-stack.html


https://www.opennetworking.org/

http://mininet.org/

http://archive.openflow.org/documents/openflow-wp-latest.pdf





https://www.opennetworking.org/images/stories/downloads/sdn-resources/white-papers/wp-sdn-newnorm.pdf









http://www.fp7-ofelia.eu/assets/Publications-and-Presentations/SDN-The-Next-Wave-of-Networking.pdf

















https://www.coursera.org/course/sdn

http://googlecloudplatform.blogspot.co.uk/2014/04/enter-andromeda-zone-google-cloud-platforms-latest-networking-stack.html

















SDN

Documents

Transcript of SDN