1. Fast Failover for Control Traffic in Software-defined Networks Globecom 2012 Neda B. & Ying Z. Presented by: Szu-Ping Wang

2. Introduction Control Plane Data Plane Traditional Switch SDN Control Plane Data Plane Control Traffic 2 / 11 ( 1 / 2 ) Controller Network Device

3. Data Plane Control Plane Control Traffic How to implement? -Adding new links? Cost increasing… -Choose one node in original topology to be controller? Introduction ( 2 / 2 ) 3 / 11

4. ? -Fast Failover Backup Link Protected 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

5. 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!

6. 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. Algorithm overview ( 1 / 1 ) 6 / 11

7. Algorithm 1 Opt. algo. ( 1 / 1 ) 7 / 11 Unprotected! Minimized the descendants number of unprotected switches. Search through all switch and choose the one that minimized the descendants number of unprotected switches.

8. 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! No need to find the routing tree first! Algorithm 2 GREEDY algo. ( 1 / 1 ) 8 / 11

9. Start from Shortest Path Tree. Try to modify the tree by replacing the edge to the tree edge. Switch ID Descendants number of unprotected switches Initial2 a0 b2 c0 abc Algorithm 3 routing. algo. ( 1 / 1 ) 9 / 11 2 0 2

10. 10 real network topologies. Calculating the descendants number of unprotected switches. SIMULATION ( 1 / 1 ) 10 / 11

11. Thanks !! Presented by: Szu-Ping Wang

12. 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