1. Data-Driven Network Connectivity Junda Liu, Scott Shenker, Baohua Yang and Michael Schapira junda@google.com

2. Control Plane Data Plane ?

3. Control Plane Data Plane Require Remote State Slower timescales Only Local State Packet timescales

4. Data-Driven Connectivity A data plane mechanism o Only local state Ensures connectivity without control plane o Simple state transitions o No message exchange o No packet labeling Intra-domain

5. Data-Driven Connectivity Forward Packets... Traffic Engineering Optimize Routes Maintain Connectivity... Maintain Connectivity Forward Packets... Traffic Engineering Optimize Routes... Traditional ModelDDC Model

6. The Difference Control Plane Shortest Path Data Plane Control Plane Multi Path Data Plane Control Plane DDC Data Plane Invoke Control Plane

7. To Begin With Destination-based forwarding Initially for every router, a link is either outgoing or incoming Essentially a DAG (Directed Acyclic Graph) DDC will preserve the DAG property

8. The Idea Send packet out when you can Bounce packet back when no choice Bounce-back packet is the implicit signal Inspired by Gafni-Bertsekas link reversal routing in 1981

9. Local Port States 2 bits per port: o 1 bit for Incoming or Outgoing o 1 bit for Normal or Reversed Normal Action: IO RIRO I Send to O port Recv Pkt

10. State Transition Always have a port to send the packet!

11. State Transition Always have a port to send the packet!

12. What's left on Control Plane Route optimization o Local healing o Clear the reversed bit Load distribution o Avoid link congestion

13. Measurement: Locality of DDC AS1239 DDC has significantly smaller scope.

14. Measurement: Load Distribution Load distributing has close to optimal result

15. Conclusion Connectivity ensured by data plane Load distribution by simple control plane Future work o Handle the distributed nature of modern router architecture

16. Backup

17. Routing Along DAGs Build per-destination DAG (Directed Acyclic Graph) Detect disconnection Optimize routes continuously Avoid congestion distributedly