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

2 / 11

( 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 )

3 / 11

?- 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 )

4 / 11

• 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 )

5 / 11

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 ( 1 / 1 )

6 / 11

Algorithm 1Opt. algo. ( 1 / 1 )

7 / 11

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. ( 1 / 1 )

8 / 11

• 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 2a 0b 2c 0

a b c

Algorithm 3routing. algo. ( 1 / 1 )

9 / 11

2

0

2

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

switches.

SIMULATION ( 1 / 1 )

10 / 11

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 )

12 / 11