1. Reactive Logic in Software-Defined Networking: Measuring Flow-Table Requirements Maurizio Dusi*, Roberto Bifulco*, Francesco Gringoli”, Fabian Schneider* Roberto.Bifulco@neclab.eu * NEC Laboratories Europe “ Università degli studi di Brescia

2. Page 2 © NEC Corporation 2014 Background: SDN and OpenFlow ▌SDN: the network control plane is separated from the network data plane Forwarding Element Controller Forwarding Element Forwarding Element Control Plane Data Plane Routing Table Forwarding Table

3. Page 3 © NEC Corporation 2014 …L3_SRCL3_DSTL4_SRCL4_DST…Action OpenFlow: proactive approach Forwarding Element …L3_SRCL3_DSTL4_SRCL4_DST…Action Any112/8Any Fwd-to: 2 L3_SCR: 10.2.54.1 L3_DST: 112.45.54.176 L4_SRC: 5433 L4_DST: 80 L3_SCR: 10.2.54.1 L3_DST: 112.45.54.176 L4_SRC: 5433 L4_DST: 80 Controller flow_mod

4. Page 4 © NEC Corporation 2014 …L3_SRCL3_DSTL4_SRCL4_DST…Action OpenFlow: reactive approach Forwarding Element …L3_SRCL3_DSTL4_SRCL4_DST…Action Any112/8Any Fwd-to: 2 L3_SCR: 10.2.54.1 L3_DST: 112.45.54.176 L4_SRC: 5433 L4_DST: 80 L3_SCR: 10.2.54.1 L3_DST: 112.45.54.176 L4_SRC: 5433 L4_DST: 80 Controller flow_mod packet_in

5. Page 5 © NEC Corporation 2014 …L3_SRCL3_DSTL4_SRCL4_DST…Action OpenFlow: flow entries definition Forwarding Element …L3_SRCL3_DSTL4_SRCL4_DST…Action Any112.45/16Any Fwd-to: 2 L3_SCR: 10.2.54.1 L3_DST: 112.45.54.176 L4_SRC: 5433 L4_DST: 80 L3_SCR: 10.2.54.1 L3_DST: 112.45.54.176 L4_SRC: 5433 L4_DST: 80 Controller flow_mod packet_in L3_SCR: 10.2.54.1 L3_DST: 112.46.55.1 L4_SRC: 5433 L4_DST: 80 packet_in flow_mod …L3_SRCL3_DSTL4_SRCL4_DST…Action Any112.45/16Any Fwd-to: 2 Ant112.46/16Any Fwd-to: 1 L3_SCR: 10.2.54.1 L3_DST: 112.46.55.1 L4_SRC: 5433 L4_DST: 80

6. Page 6 © NEC Corporation 2014 …L3_SRCL3_DSTL4_SRCL4_DST…Action OpenFlow: flow entry’s idle timeout Forwarding Element …L3_SRCL3_DSTL4_SRCL4_DST…Action Any112/8Any Fwd-to: 2 L3_SCR: 10.2.54.1 L3_DST: 112.45.54.176 L4_SRC: 5433 L4_DST: 80 L3_SCR: 10.2.54.1 L3_DST: 112.45.54.176 L4_SRC: 5433 L4_DST: 80 Controller flow_mod packet_in 1 2 3

7. Page 7 © NEC Corporation 2014 Understanding control/data plane interactions ▌Switch simulator Based on the reactive OpenFlow model Flow entry definition is configurable (also the idle timeout) Input: traffic trace Output: number of packet_in, flow_mod per second number of flow entries in the flow table per second ▌Simplified controller model: Only packet_in and flow_mod interactions The same flow entry definition is applied for all the incoming flows E.g., flow entry is defined by the destination IP address/32 and idle timeout is 10 seconds.

8. Page 8 © NEC Corporation 2014 Datasets ▌Access network DSLAM of an European ISP, 2007 (protected by NDA  ) University of Brescia campus network’s edge router, 2009 (publicly available) ▌Core network PAIX, Tier1 backbone link, 2005 (publicly available) CAIDA, Tier1 backbone link, 2013 (publicly available)

9. Page 9 © NEC Corporation 2014 What if? Proactive approach ▌Number of flow table entries in the switch flow table ACL Routing/Policy-based routing ▌How this numbers compare to actual switches’ flow tables? Hardware OpenFlow switches can host a few 1000s entries.

10. Page 10 © NEC Corporation 2014 Playing with the idle timeout (DSLAM trace) ▌Flows are not always active! Increase

11. Page 11 © NEC Corporation 2014 Impact of flow entry definition ▌Timeout fixed at 10s (common value in many OpenFlow Controllers) 4500 350

12. Page 12 © NEC Corporation 2014 Impact of flow entry definition ▌Timeout fixed at 10s (common value in many OpenFlow Controllers) 60k 4k

13. Page 13 © NEC Corporation 2014 Conclusion ▌Reactive, or partially-reactive control plane enables advanced SDN use cases; ▌Using reactive entries installation can reduce the flow table size by orders of magnitude Requires the switch to handle more frequent flow table updates; ▌In access networks current OpenFlow switches can cope the flow table requirements, also with fine granular flow definition; ▌In core networks current OpenFlow switches can only be used with coarse grained flows; ▌Understanding the effects of a reactive control plane on the flows delay is a required next step.