1 / 33

CBRP : A C luster- b ased R outing P rotocol for Mobile Ad hoc Networks

CBRP : A C luster- b ased R outing P rotocol for Mobile Ad hoc Networks. Presented by: Jiang Mingliang Supervised by: Dr Y.C. Tay, Dr Philip Long. Presentation Outline. Project Overview and Objectives Related Works CBRP: Motivations CBRP: the Details Performance Evaluation

merry
Download Presentation

CBRP : A C luster- b ased R outing P rotocol for Mobile Ad hoc Networks

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. CBRP: A Cluster-based Routing Protocol for Mobile Ad hoc Networks Presented by: Jiang Mingliang Supervised by: Dr Y.C. Tay, Dr Philip Long

  2. Presentation Outline • Project Overview and Objectives • Related Works • CBRP: Motivations • CBRP: the Details • Performance Evaluation • Conclusion and Future Work

  3. Project Overview • Mobile Ad hoc Networks (MANET), its applications and challenges • IETF working group MANET

  4. Project Overview • MANET characteristics ( & the difficulties for routing protocols) • Dynamic Topology • Limited Link Bandwidth • Limited Power Supply for Mobile Node • Need to scale to large networks

  5. Project Objective • Design a routing protocol for MANET that is: • efficient • scalable • distributed and simple to implement • Evaluate CBRP through simulation • compare with different design alternatives • compare against other MANET protocols

  6. Related Works • Existing MANET protocols: discover routes on-demand (re-active) Source routing DSR Table driven AODV, ABR, TORA MANET routing protocols Variation of distant vector? DSDV Maintain updated routes (pro-active) OLSR Variations of link state routing?

  7. Related Works • Problems with pro-active routing protocols • high overhead in periodic/triggered routing table updates • low convergence rate • waste in maintaining routes that are not going to be used!! • Simulating results have shown RIP, OSPF, DSDV fails to converge in highly dynamic MANET.

  8. Related Works • Re-active Routing Protocols • prohibitive flooding traffic in route discovery • route acquisition delay • every route breakage causes a new route discovery • Works in trying to reduce flooding traffic • LAR (GPS for every mobile node?) • DSR (aggressive caching)

  9. CBRP: Motivations • Design Objective: a distributed, efficient, scalable protocol • Major design decisions: • use clustering approach to minimize on-demand route discovery traffic • use “local repair” to reduce route acquisition delay and new route discovery traffic • suggest a solution to use uni-directional links

  10. CBRP: Protocol Overview

  11. Cluster Formation • Objective: • Form small, stable clusters with only local information Mechanism: Variations of “min-id” cluster formation algorithm. Nodes periodically exchange HELLO pkts to • maintain a neighbor table • neighbor status (C_HEAD, C_MEMBER, C_UNDECIDED) • link status (uni-directional link, bi-directional link) • maintain a 2-hop-topology link state table HELLO message format:

  12. 11 8 9 4 10 3 1 2 7 5 6 Cluster Formation (an example) • Variation of Min-ID • Minimal change • Define Undecided State • Aggressive Undecided -> Clusterhead e.g. 2’s neighbor table

  13. 11 8 9 4 10 3 1 2 7 5 6 Adjacent Cluster Discovery • Objective: • For clusterheads 3 hops away to discover each other • Mechanism: • Cluster Adjacency Table exchanged • in HELLO message • e.g. 4’s Cluster Adjacency Table

  14. [3,1,8,11] 11 (D) 11 9 [3,1,8] 8 4 10 3 3 (S) 1 [3,1] 2 7 6 5 [3,1,6] Route Discovery Source S “floods” all clusterheads with Route Request Packets (RREQ) to discover destination D [3]

  15. 11 (D) 11 [11] [11,9] 9 [11,9,4] 8 4 10 3 3 (S) [11,9,4,3] 1 [11,9,4] the computed strict source route of 3->11 is: [11,9,4,3] 2 7 6 5 Route Reply • Route reply packet (RREP) is sent back to source along reversed “loose source route” of clusterheads. • Each clusterhead along the way incrementally compute a hop-by-hop strict source route. the reversed loose source route of RREP: [11,8,1,3]

  16. 11 (D) 11 9 8 4 10 3 (S) 3 1 2 7 6 5 Route Reply • Route reply packet (RREP) is sent back to source along reversed “loose source route” of clusterheads. • Each clusterhead along the way incrementally compute a hop-by-hop strict source route. the reversed loose source route of RREP: [11,8,1,3] the computed strict source route of 3->11 is: [11,9,4,3]

  17. 11 9 8 4 10 3 1 2 7 6 5 Route Error Detection • Use source routing for actual packet forwarding • A forwarding node sends a Route Error Message (ERR) to packet source if the next hop in source route is unreachable 11 (D) Source route header of data packet: [3,4,9,11] 3 (S) Route error (ERR) down link: {9->11}

  18. Local Route Repair in CBRP • Objective • Increase Packet Delivery Ratio • Save Route Rediscovery flooding traffic • Reduce overall route acquisition delay • Mechanism • Spatial Locality

  19. 11 9 8 4 10 3 1 2 7 6 5 Local Route Repair • A forwarding node repairs a broken route using its 2-hop-topology information and modifies source route header accordingly. • Destination node sends a gratuitous route reply to inform source of the modified route 11 (D) Source route header of data packet: [3,4,9,11] 3 (S) Route error (ERR) down link: {9->11}

  20. 11 9 8 4 10 3 1 2 7 6 5 Local Route Repair • A forwarding node repairs a broken route using its 2-hop-topology information and modifies source route header accordingly. • Destination node sends a gratuitous route reply to inform source of the modified route 11 (D) Source route header of data packet: [3,4,9,11] 3 (S) Modified source route [3,4,9,8,11]

  21. Local Route Repair • A forwarding node repairs a broken route using its 2-hop-topology information and modifies source route header accordingly. • Destination node sends a gratuitous route reply to inform source of the modified route 11 (D) 11 Source route header of data packet: [3,4,9,11] 9 8 4 10 3 3 (S) 1 Gratuitous route reply [3,4,9,8,11] 2 7 6 5

  22. Utilize Unidirectional links • Cause of unidirectional links • Hidden Terminal • Difference in transmitter power or receiver sensitivity. • Pitfalls with unilinks • Discovery of (dead) unilinks • Problems with 802.11 RTS/CTS/Snd/Ack, ARP

  23. Utilize Unidirectional links • Selective use of Unilinks in CBRP 5 6 7 9 2 1 4 8 3 10

  24. Supercluster • Taking advantage of hidden stability from the changing topology • Better support for natural mobility patterns • Merge stable clusters into supercluster • to be further studied

  25. Performance Evaluation • Goals • show the robustness of CBRP’s packet delivery with reduced overhead. • evaluate how CBRP scales to larger networks • compare different design alternatives (with/without local repair) • compare CBRP with other MANET routing protocols • Tools • ns (network simulator) with wireless extension. • features • models Lucent WaveLAN DSSS radio with signal attenuation, collision and capture. • implements IEEE 802.11 link layer

  26. Simulation Environment • Mobility Model(random way-point) • Nodes move within a fixed rectangular area m x n • Each node chooses a random destination and move toward it at a speed uniformly distributed between 0 and max_speed • When reaching its destination, a node pauses for pause_timebefore start moving again. • Traffic Model • A node creates a session with a randomly selected destination node. • Packets of fixed size 128 byte are sent with constant sending rate of 4 pkts/sec

  27. Simulation Parameters • Simulator parameters • CBRP implementation parameters

  28. 1. Packet delivery ratiowith respect to network mobility • Network mobility is directly affected by pause_time. • pause_time has value {0, 30s, 60s, 120s, 300s, 600s} with 0 representing constant mobility and 600s signifying a stationary network.

  29. 2.Packet delivery ratio with respect to network size • Simulated network of nodes {25, 50, 75, 100, 150} with constant mobility, 60% of nodes have active CBR sessions.

  30. 2.Routing Overhead with respect to network size Routing overhead(normalized) = #routing pkts sent/ #data pkts delivered.

  31. Milestones • Aug 98, CBRP as Internet Draft • Aug 98, in Chicago Presentation to the IETF • Oct 98, presentation to MMlab, EE, NUS • Nov 98, Presentation to IETF in Orlando • Mar 99, paper submitted to Globecom99

  32. Limitations of CBRP • Source Routing, overhead bytes per packet • Clusters small, 2 levels of hierarchy, scalable to an extend

  33. Conclusion • CBRP is a robust/scalable routing protocol superior to the existing proposals • Further study on Superclustering • QoS, Multicast support in CBRP

More Related