traffic engineering in software-defined networks

UWB

Traffic Engineering in Software-Defined Networks

Hai Dinh Tuan

Next Generation Networks & Future Internet Technologies Seminar

• Introduction – Traffic Engineeirng & SDN

• What's new with TE in SDN

• New Traffic engineering techniques in SDN

• Conclusion

Agenda

Introduction

Introduction - Traffic Engineering

Traffic Engineering (TE) can be defined as a set of techniques, designed

to manage the allocation of network resources to carry traffic subject

to constraints

The separation of

control plane (routing

functionalities) and

data plane (forwarding

functionalities)

Introduction - SDN

Source: SDNCentral

Traffic Engineering in SDN

1. Future networks require a high performance and highly

flexible infrastructure• Rapid expansion of today Internet

• The growth of mobile devices, as well as real-time data

2. New traffic engineering techniques must face

unprecedented challenges• Old periodic data sampling mechanism can create a significant

overhead.

Future networks requires new techniques

1. Simplified network management• Controller has the global view of network

• Focus on specifying network-level objectives

2. Flexibility• Eliminate vendor lock-in situation

• New network features can be easily developed and deployed

3. Reliability• Programmability makes network behavior more deterministic

SDN makes TE easier

4. Higher Efficiency• Organizations can develop their own algorithms to achieve

optimal performance

• Controller can be regularly upgraded with the latest hardware

technologies

5. Innovation support• Develop new function for controller without modifying switches

and vice versa

• Enables external contributions

SDN makes TE easier (2)

Specific techniques

Research directions in TE for SDN

1. Efficient flow managementWhen there is a high number of incoming flow, overload may occur

2. Fast recovery mechanismController must recalculate new routes and notify all related

switches in case of network failure

3. ConsistencyGuarantee consistency during network updates

4. Low-overhead traffic analysisSDN requires new network management mechanisms





3. ConsistencyGurantee consistency during network updates


How to avoid overload when there are many new flows are injected?

Flow management

1. Switch load-balancingEqual Cost Multi-Path Routing (ECMP)

3. Controller load-balancingLogically distributed controller

Physically distributed controller

Hierarchical controller

Multi-threaded controllers

4. Using multiple flow tablesAlready used from OpenFlow 1.1

DIFANE

Controller should

generate rules, but

don't need to be

involved in the real-

time handling of data

packets

The switches handle

all packets in the data

plane DIFANE flow management architecture [1]

What is the best way to implement a fault tolerance mechanism?

Fault tolerance

1. Fault tolerance for data planeData plane restoration (reactive)

Data plane protection (proactive)

3. Fault tolerance for control planeBackup controller

CPRecovery

CPRecovery controller backup mechanism [2]

A component runs on top of the

network OS, support Primary-

Backup mechanism.

Switch uses inactivity probes to

check Primary controller. If its

down, switch initiates

connection to secondary

controller.

How to enforce policies during a network change?

Consistency during network updates

1. Per-packet consistencyEach packet is forwarded through the network according to only

one policy, not the mix of old and new policies

3. Per-flow consistencyAll packets in the same flow will be processed by the same network

configuration

Using configuration version

• Ingress switch marks a configuration version on each

incoming packet

• Packets are processed based on their version value.

• Ingress switch update configuration version when there is

update

• When all packets belong to old policy has left the

network, controller removes old rules from all switches

How to develop network management tools suit better to SDN?

Traffic Analysis

1. Monitoring frameworkProvides support for network management applications

2. Network invariants checkMake sure that every rule insert/delete operation doesn't lead to net

work inconsistency

3. Debugging toolsIt is possible to debug a whole SDN network as a software

PayLess

PayLess provides a RESTful API

for developing monitoring

applications. They can be

written in any language and can

decide what, where and when to

collect statistics

PayLess (2)

Adjust the monitoring frequency according to network load

by adaptive monitoring algorithm:• Assign a monitoring time out to each flow

• Query the switch(es) for flow statistics when timeout expires

• If no significant traffic change, increase the timeout

• If change in traffic is significant, decrease the timeout

=> Flows that significantly contribute to link utilization has a higher

polling frequency

Conclusion

Conclusion

1. Challenges go hand-in-hand with oppotunitiesThis paradigm shift has many advatages but also requires new

design for TE tools.

2. Many unsolved problemsHybrid SDN network?

Incremental implementation of SDN?

3. Requires collaboration between academia and industry

UWBTHANK YOUHai Dinh Tuan

Next Generation Networks & Future Internet Technologies Seminar

traffic engineering in software-defined networks

Technology