Fast Failoverfor

Control Trafficin

Software-defined Networks

Globecom 2012Neda B. & Ying Z.

Presented by: Szu-Ping Wang

Introduction

Control Plane

Data Plane

Traditional Switch SDN

Control Plane

Data Plane

Control Traffic

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( 1 / 2 )

Controller

Network Device

DataPlane

ControlPlane

Control Traffic

How to implement?- Adding new links?

Cost increasing…

- Choose one node in original topology to be controller?

Introduction ( 2 / 2 )

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?- Fast Failover

Backup LinkProtected Switch

Choose the best placement with minimum number of unprotected switch.

• How to choose the best placement on the original topology?

Controller Placement( 1 / 2 )

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• Define the Protected Switch:

1. Check the other nodes that is not in the same sub-tree.

Special case: controller’s immediate children check the all other nodes except controller in step 1.

Protected!

Controller Placement( 2 / 2 )

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2. Does there exist a link between target switch and the set of green circle?

Unprotected!

• Two algorithms for choosing the best location for the network controller.

• One algorithm for improving the resiliency of shortest path routing tree.

• The ideas are all about protected switches numbers.

Algorithmoverview

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Algorithm 1Opt. algo.

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Unprotected!

Unprotected!

Minimized the descendants number of unprotected switches.

• Search through all switch and choose the one that minimized the descendants number of unprotected switches.

• It’s non-practical if the size of the network is large!

• Heuristic Algorithm.

• Check only the neighbors of controller and choose the one that maximized the number of protected switches.

Special case: controller’s immediate children check the all other nodes except controller in step 1.

Protected!Protected!

• No need to find the routing tree first!

Algorithm 2GREEDY algo.

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• Start from Shortest Path Tree.• Try to modify the tree by replacing the edge to

the tree edge.Switch

IDDescendants number of unprotected switches

Initial 2

a 0

b 2

c 0

a b c

Algorithm 3routing. algo.

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2

0

2

• 10 real network topologies.• Calculating the descendants number of unprotected

switches.

SIMULATION ( 1 / 1 )

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Thanks !!

Presented by: Szu-Ping Wang

• There is no analysis for Algorithm 2.

• The algorithm 1 and 3 are straightforward.

• It’s practical for implement SDN on original topology.

conclusion ( 1 / 1 )

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