Volcano Routing Scheme Routing in a Highly Dynamic Environment

1. Volcano Routing SchemeRouting in a Highly Dynamic Environment Yashar Ganjali Stanford University Joint work with: Nick McKeown SECON 2005, Santa Clara, CA, Sep. 27, 2005 yganjali@stanford.edu http://yuba.stanford.edu/~yganjali/

2. Outline • Routing in MANETs • Slowly changing topology • Highly changing topology • Volcano Routing Scheme • Single Flow • Multiple Flows • Evaluation • Mathematical Results • Simulations Volcano Routing Scheme

3. s d Routing in Data Networks • Routing in data networks • Phase 1: Route discovery • Proactive • Reactive or on-demand • Phase 2: Packet forwarding • Routing overhead is reduced • Discovery happens very infrequently Volcano Routing Scheme

4. Routing in MANETs • Changes in topology • Node movements • Wireless link issues • Route changes more frequent • Temporary partitioning in network • Increased overhead of route discovery phase • Accelerate/defer the route discovery process • Use flooding to find routes as quickly as possible • Buffer when partitioned Volcano Routing Scheme

5. Highly Dynamic Topology • What if topology changes constantly? • Quickly moving nodes • Highly dynamic environment • Adversarial model • Route discovery failure  two-phase routing doesn’t work Volcano Routing Scheme

6. One-Phase Routing • Eliminate explicit route discovery • Assign a function to nodes that determines the direction of packets • Physical location of nodes: • Some variations of geographical routing • Number of packets buffered in a node: • Volcano Routing Scheme (VRS) Volcano Routing Scheme

7. Outline • Routing in MANETs • Slowly changing topology • Highly changing topology • Volcano Routing Scheme • Single Flow • Multiple Flows • Evaluation • Mathematical Results • Simulations Volcano Routing Scheme

8. Volcano Routing Scheme (VRS) • Lava flows towards the sea (low altitude) • Local balancing of load • Obstacles do not stop lava • No explicit route discovery • Reordering layers doesn’t disrupt the flow Volcano Routing Scheme

9. Volcano Routing Scheme • At the beginning of each time slot: • Packets are generated at the source. • During the time slot: • Each link (v,w)for which P(v)– P(w)>  transfers one packet from v to w. •  is called transfer threshold. • At the end of the time slot: • Packets which arrive at destination are removed. Volcano Routing Scheme

10. Simple Example • Time slot 1 • Packet generated • Time slot 2 • Packet generated • Two transfered • One received • Time slot 3 • Packet generated • Time slot 4 • Packet generated • One transfered • One received • … m s d Volcano Routing Scheme

11. Volcano Routing Scheme Volcano Routing Scheme

12. Advantages No explicit route discovery Completely distributed Low complexity Minimal amount of control traffic Suitable for highly dynamic environments System is proved to be stable Path taken by packets is near optimal Limitations Requires continuous stream of packets from source to destination Packet reordering might happen Pros and Cons Volcano Routing Scheme

13. Multi-Flow VRS • Time-Division VRS • Divide time equally among K flows • Maximum-Pressure VRS • For a link (v,w) serve the flow i which has the maximum amount of pressure Pi(v)- Pi(w) Volcano Routing Scheme

14. Multi-Flow VRS Volcano Routing Scheme

15. Outline • Routing in MANETs • Slowly changing topology • Highly changing topology • Volcano Routing Scheme • Single Flow • Multiple Flows • Evaluation • Mathematical Results • Simulations Volcano Routing Scheme

16. Evaluation Method • Metrics • Stability (packet loss ratio) • Queue size distribution • Routing path length • Factors • Connectivity (communication range, number of nodes, …) • Number and amount of flows • Mobility process • Transfer threshold  Volcano Routing Scheme

17. s d Stability Strict Stability: total number of packets in the network is bounded. F-Min-Provisioned: capacity of minimum cut is at least F. Theorem. If the source injects at most Fpackets the system remains strictly stable if the network is F-min-provisioned. Volcano Routing Scheme

18. Packet Loss vs. Flow Demand • 100 nodes distributed uniformly in a 1x1 square • CR = 0.26 • Velocity ~ [0.01..0.2] •  = 2 • Average number of neighbors = 20 • Stability independent of buffer size Volcano Routing Scheme

19. Packet Loss: TD-VRS vs. MP-VRS Volcano Routing Scheme

20. Average No. of Neighbors = Flow Demand Packet Loss: Communication Range Volcano Routing Scheme

21. Packet Loss: Mobility Process • No difference between random walk and waypoint model • Stability independent of velocity • Extremely low velocity can cause instability Volcano Routing Scheme

22. Queue Size Distribution Volcano Routing Scheme

23. Near-Optimal Paths • In a fixed topology packets take shortest paths. • If flow rate is D- we can choose such that • Almost surely all packets take the firstD shortest paths. • Trade-ff between • Number of outstanding packets • Routing path length Volcano Routing Scheme

24. Path Length vs. Delta Volcano Routing Scheme

25. Summary • Introduced Volcano Routing Scheme • Distributed, fast, low complexity, … • Need stream of packets • Variations of VRS: Time Division, Maximum Pressure • Stable under admissible traffic • Short queuing delay • Routing path near optimal Volcano Routing Scheme

26. Thank You! Questions? Volcano Routing Scheme

27. Extra Slides Volcano Routing Scheme

28. Generalizing to More Flows • Flow 1 • Source: node 1 • Destination: node 4 • Flow 2 • Source: node 4 • Destination: node 1 Volcano Routing Scheme

29. Packet Loss: Flow Demand Volcano Routing Scheme

30. Packet Loss: Number of Nodes Volcano Routing Scheme

31. Loss vs. Velocity Volcano Routing Scheme

32. Packet Loss vs. Node Velocity Volcano Routing Scheme

33. Queue Size Distribution: Delta Volcano Routing Scheme

34. Queue Size Distribution Volcano Routing Scheme