1. OpenFlow: Enabling Innovation in Campus Networks Yongli Chen

2. Problems  Recently, it is difficult to make real-world impact on network innovation.  Due to:  Enormous base of equipment  Cisco’s annual sale in 2015 is $49.16 Billion  Many kinds of protocols  Total number of RFCs > 7,400  Reluctance to experiment with production traffic  Thus, there is almost no practical way to experiment with new network protocols in realistic network environment.

3. Solution: SDN(Software Defined Networking)  GENI: A researcher will be allocated a slice of resources across the WHOLE network  However, plans for nationwide like GENI are ambitious, costly, and they take years to be deployed.  PC with several network interfaces and Operating System  But PC’s performance is less than satisfying, comparing to wiring closet: PCCollege Wiring Closet Packet processing rate1Gb/s100Gb/s Number of ports~10~100

4. Solution: OpenFlow  Enabling researchers to run experimental protocols in the campus networks we use every day.  Which means:  Take less time to deploy(compare to large scale SDNs like GENI)  Acceptable cost  In short, realistic.

5. OpenFlow: Goals  High performance/cost ratio  Capable of supporting a broad range of research  Isolation of production traffic and experimental traffic  Consistent with vendors’ need for closed platforms

6. OpenFlow switch: meets all 4 goals  An OpenFlow switch consists of at least three parts:  1. A Flow Table, used to instruct the switch how to process the flow.  2. A Secure Channel, used to connect the switch to a remote control process(called Controller) using  3. The OpenFlow Protocol, which provides an open and standard way for a controller to communicate with a switch.

7. OpenFlow: concept explained OpenFlow decouples data plane & control plane inside the switch, and allows control plane to exist outside of the switch. This external control plane is controller. Youtube Explanation

8. OpenFlow: What is flow?  Flow is broadly defined, for example:  A TCP connection  All packets with the same VLAN tag  All packets from the same switch port  Etc…  In general, you can define flow by yourself.

9. OpenFlow: Flow Table of OpenFlow switch  An entry in the Flow Table contains three fields:  1. A packet header that defines the flow.  2. The action, which defines how the packets should be processed.  3. Statistics, which keep track of the number of packets and bytes for each flow.

10. OpenFlow: Actions on Flows by OpenFlow switches  1. Forward this flow’s packets to a given port.  This action allows packets to be routed.  2. Encapsulate and forward this flow’s packets to a controller.  This action allows controller to decide whether the flow should be added to the Flow Table.  3. Drop this flow’s packets.  This action can be used for security reasons, etc.  4. Optional: Forward this flow’s packets through the switch’s normal processing pipeline.  This action allows experimental traffic to be isolated from production traffic.  Alternatively, isolation can be achieved through defining separate sets of VLANs.  We can also treat OpenFlow as generalization of VLAN!

11. OpenFlow: Upgrade to current devices  Flow Table will re-use existing hardware, such as TCAMs(ternary content-addressable memory) used in modern switches and routers.  Secure Channel and OpenFlow Protocol will be supported through devices’ operating system ugrade.

12. OpenFlow Example: New Data Center (from OpenFlow.org)  Cost  200,000 servers  Fanout of 20 -> 10,000 switches  $5k vendor switch = $50M  $1k commodity switch = $10M  Savings in 10 data centers = $400M  Control  More flexible control  Tailor network for services  Quickly improve and innovate

13. OpenFlow: Summary  OpenFlow is a pragmatic compromise that allows researchers to run experiments on heterogeneous switches and routers.

14. OpenFlow: Discussion  How about reliability of OpenFlow?  Controller: Single point of failure  How about scalability of OpenFlow?  Flow table: How many flows can it handle?  How secure is OpenFlow?  Attacks are possible

15. OpenFlow: Q&A  Any questions?

16. Thanks!