Tesseract A 4D Network Control Plane

1. Carnegie Mellon University Microsoft Research Rice University Presented by: Alberto Gonzalez, Whitney Young TesseractA 4D Network Control Plane

2. Current Designs • No direct control • Subtle dependencies • Example: load balance forwarding by tuning OSPF link weights, but impacts inter-domain routing

3. Services: Dissemination Node configuration 4D Architecture Control plane: • Decision • Dissemination • Discovery • Data

4. Design

5. Design Goals • Timely reaction to network changes • Resilient to decision plane failure • Robust and secure control channels • Minimal switch configuration • Backward compatibility • Support diverse decision algorithms • Support multiple data planes

6. Implementation Overview • Switch • Implements data plane • Decision Element (DE) • Implements discovery, dissemination, and decision planes

7. Decision Plane • Any network control algorithm can be easily integrated • Incremental shortest path first • Spanning tree • Joint packet filtering/routing • Link cost-based traffic engineering • Resiliency to DE failure • Hot standbys receiving heartbeats

8. Dissemination Plane • Goal: communication between DEs and switches • DEs handle most of dissemination plane, but switches help out • Path to destination handled by DE • Switches have separate queue and dissemination packets have higher priority • Security (protects switches, info passed through dissemination plane, and compromised DEs)

9. Discovery Plane • Goal: minimize manual configuration • Switches send HELLO messages • DEs handle instructing the switches on what to do once active • Initiate eBGP session with outside world • Backward compatibility (bootstrapping end hosts) • Discovery plane as DHCP proxy

10. Data Plane • Configured by decision plane • WriteTable exposed with simple interface to provide configuration service to decision plane • Allows easy implementation of different services • Decision/Dissemination Interface • Function independently of each other • Only 3 functions used to interface between them (2 more simply to improve performance)

11. Switch& Regional Failures Performance Evaluation • Single Link Failures • Link Flapping • 10-hop to 12-hop change • Tesseract can handle network changes

12. Performance Evaluation • 1347 nodes & 6244 edges • DE Computation Time • Worst Case: 151ms • 99th percentile: 40ms • Bandwidth overhead • Worst Case: 4.4MB • 90% of switched updated with new state

13. Performance Evaluation • Failover times

14. Applications • In enterprise network: • Computers both new routes & packet filter placements • Loads into routers with no forbidden traffic leaked • No human involvement once security policy is specified

15. Ethernet • Key features • Widely implemented frame format • Support for broadcasting frames • Transparent address learning model • Tesseract keeps these properties.

16. Ethernet • Through point comparisons • Control Plane for TCP flows • Started at 570Mbps • Leveled at 280Mbps after a failure • Conventional RSTP Control Plane • Starts at 280Mbps • Hit zero after failure • Recovered after 7-8 seconds at ~180Mbps

17. Summary • Tesseract • Robust • Decission/Dissemination Planes • Secure • Enterprise Network • Resuable • Ethernet or IP • Good Performance • Convergence & Throughput • Scalable • 1,000+ Switches • Enables direct Control • Easier to Understand and Deploy