Scalable Source Routing

Transcription

1 Scalable Source Routing January 2010 Thomas Fuhrmann Department of Informatics, Self-Organizing Systems Group, Technical University Munich, Germany

2 Routing in Networks You re there. I m here. Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 2

3 Routing in Networks Have full topology and use Dijkstra Use Bellman-Ford (i.e. distance vectors) Use coordinates Flood the graph and build up state Have source routes Who assigns addresses? Network or you? What about mobility? Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 3

4 Scalable Source Routing breaks the Trade-Off SSR Few control messages Little routing state Routing Tables Shortest Paths Flooding Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 4

5 Agenda 1. Intoduction 2. Peer-to-Peer Overlay Networks 3. Scalable Source Routing 4. Mobility & Churn 5. Summary Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 5

6 Structured Peer-to-Peer Networks Virtual Address Space Peer-to-Peer Overlay Network Internet Existing Network Infrastructure Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 6

7 Structured Peer-to-Peer Networks Internet there Proximity-aware Key Based Routing here Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 7

8 Scalable Source Routing 13 Node 13 virtually not as far as node Node 88 beyond destination Node 17 is best choice Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 8

9 Scalable Source Routing Node 19 virtually not as far as node Node 32 is the best choice. Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 9

10 Scalable Source Routing Node 27 is the only option, but it s in the wrong direction SSR Rule: Each node must have a source route to its virtual neighbor. Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 10

11 Scalable Source Routing Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 11

12 Scalable Source Routing Fuhrmann, A Self-organizing Routing Scheme for Random Networks, Networking Caesar et al. Virtual Ring Routing: Network Routing Inspired by DHTs, SIGCOMM Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 12

13 Iterative Successor Search Successor Notification Successor Notification Viewed from node 13 Viewed from node 101 Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 13

14 Iterative Successor Search Successor Update Node 29 can resolve the inconsistency Notifications: I3 29 Notify 101 I0I 29 Notify Updates: I3 29 Update I0I 29 I0I 29 Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 14

15 Source Route Cache Nodes use static memory: Each node stores its direct physical neighbors. Each node stores a source route to its successor. Each node stores a source route to its predecessor (to be able to send updates). All remaining memory (assigned to routing) is used to cache source routes in a LRU manner Source Route Cache Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 15

16 Source Route Cache Upon a cache miss the message is forwarded to the node that Lies before the target (in direction of the ring), is physically closest to the forwarding node, and that virtually closest to the target. (Rules applied in that order.) Example: Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 16

17 Source Route Cache The cache accumulates short routes: Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 17

18 Simulation Results (1) Consistency Successful delivery [%] Small-world topology, nodes, cache size 256 Simulation time [rounds] Routing stretch [Achieved hops : shortest path] Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 18

19 Simulation Results (2) Cluster Formation Unit disk graph with uniformly random node positions (critical density). Forwarding to physical neighbor according to routing rule leads to cluster formation. Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 19

20 Simulation Results (3) Node Specialization Address distribution in the cache Relative Frequency Simulation result equally distributed exponentially distributed Address distance Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 20

21 Scalable Source Routing Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 21

22 Self-Organization in SSR In principle, there could be many intermediate nodes. In practice this is rare: The larger the gap, the higher the probability that a physical proximate node fills the gap. Nodes specialize on their virtual neighborhood. Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 22

23 Self-Organization in SSR Neighborship Recommendations (indirect virtual neighbors) Neighborship Corrections (direct virtual neighbors) Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 23

24 Scalable Source Routing Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 24

25 Dealing with Churn and Mobility Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 25

26 Rule 1: Don t pollute the caches You may cache source routes from packets that you forward; but you must not cache those parts of the route that have not yet been used! Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 26

27 Rule 2: Keep the intermediate nodes Keep the intermediate nodes, which appended to the path, in the packet header, so that you can backpropagate a failure notification! Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 27

28 Rule 3: Use the physical neighbors Remember the physical neighbors of your virtual neighbors and use them as intermediate destination in case you lost the route to a virtual neighbor Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 28

29 Simulation results (4) Node Churn Acknowledged [%] Node half-life time [min] 8000 nodes Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 29

30 Simulation (5) Compare to AODV and DSR Successful delivery [%] Hybrid MANET (5% fixed wired nodes), Mobile nodes 1m/s Number of nodes Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 30

31 Simulation Results (6) Node velocity Successful delivery [%] 450 node pure MANET Node velocity [m/s] Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 31

32 Simulation Results (7) Delay distribution Successful delivery [%] 612 node hybrid MANET Delay [ms] Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 32

33 Simulation Results (8) Hop distribution Successful delivery [%] 800 node hybrid MANET Hop Count Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 33

34 Comparison of SSR and VRR Fuhrmann, SSR, Networking 2005 Caesar et al., VRR, SIGCOMM Source Routes Limited state per node Large packet headers (cf. source routes), but reduction technique can reduce to local next hop IDs Consistency without flooding Tables with destination / path ID Tables with next hop / path ID Potentially unlimited state Small packet headers Representative nodes must flood the network Comparison shows slight advantage for SSR, unless the bandwidth saturates. Fixed memory demand of SSR might be beneficial for implementation in hardware. Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 34

35 The Linyphi Mesh Network IPv6 IPv6 IPv6 IPv6 Scalable Source Routing Protocol Pengfei Di et al. Linyphi: Creating IPv6 Mesh Networks with SSR. Concurrency and Computation, Vol 20, Issue 6, April 2008 Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 35

36 Other Activities in the Group Overview Routing in Virtual Address Spaces Applications in Distributed Computing Igor Overlay Scalable Source Routing Igor File System Virtual Machines Internet Key Based Routing Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 36

37 Summary Scalable source routing is a self-organizing routing scheme for large networks with flat address space. It consists of a few simple rules, and requires only little per-node state. It is very robust in face of mobility and node churn. Prototype implementations exist, but so far they ve been tested on small scale only. Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 37

38 Thank you! Thomas Fuhrmann Department of Informatics Self-Organizing Systems Group Technical University Munich, Germany Scalable Source Routing, January 2010 Thomas Fuhrmann, Technische Universität München, Germany 38