MPR Extension for OSPF on MANETs draft-baccelli-ospf-mpr-ext-01.txt Emmanuel Baccelli

1. MPR Extension for OSPF on MANETs draft-baccelli-ospf-mpr-ext-01.txt Emmanuel Baccelli 65th IETF OSPF WG in Dallas, March 23rd 2006

2. Agenda • MANET-OSPF background • Topology reduction with MPR links • Flooding optimization with MPRextension

3. Keys to efficient OSPF on MANETs MANET-OSPF DT results: • Need overhead reduction • Need to focus on LSUpdate Reduction can be achieved: • with flooding optimization • with topology reduction • with adjacency limitation benchmark results Henderson, Spagnolo et al.

4. OSPF extensions for MANET • No change to traditional OSPF • Existing code/protocol unaltered • MANET “instabilities” won’t affect OSPF stability • Leverage existing code/mechanisms • Changes concern only OSPF MANET interfaces • Specific MANET interface type addressing: • highly dynamic topology, scalability, radio link fading • draft-baccelli-ospf-mpr-ext-01proposes: • topology and adjacency reduction • flooding optimization

5. MPR: Multi-Point Relays • MPR selects a subset of • links and nodes to achieve • optimized network coverage. MPR MPR MPR

6. Topology Reduction withMPR Links Adjacency Limitation • MPR yields naturally adjacency limitation • Adjacencies are between: • MPR and MPR-selectors (MPR links) • Some routers form adjacencies with every neighbor • Hybrid routers (with both traditional and MANET interfaces) • Results in ”lossless” topology reduction

7. D S D S MPR links guarantee shortest paths 2-WAY link Adjacency MANET-OSPF MANET-OSPF Case 1 • MANET source hop • may be 2-WAY Case 2

8. D OSPF Heterogeneous Topologies • paths to/through a MANET: • made of adjacencies • the best paths (shortest) MANET-OSPF OSPF S D MANET-OSPF Case 1 OSPF OSPF S Case 2 2-WAY link Adjacency

9. D Path costs are minimal 2-WAY link Adjacency MANET-OSPF 1 1 1 1 1 1 1 S OSPF no out-of-track forwarding

10. MPR Links Topology Reduction Evaluation Unit Disk Graph simulations: speed 60 mph, radio range 1 mile, 40 - 100 routers Full topology Full topology MPR-OSPF MPR-OSPF number of links in advertized topology MANET LSUpdate overhead (number of advertized links per minute)

11. Flooding Optimization with MPR • MPR selection can also be used to optimize flooding • Only MPRs retransmit • The whole network is covered • The number of retransmitters is drastically reduced MPR S S MPR

12. Flooding Optimization with MPR Unit Disk Graph simulations: 2x2 miles, radio range 1 mile, 40 - 100 routers Traditional flooding MPR flooding Number of retransmitters to complete flooding

13. OSPF MPR Extension in a Nutshell • MPR information is signalled only on MANET interface,with HELLO packets + appendedLLS information. • MPR is validated to be simple and efficient by manet-wg • Drastic overhead reduction (topology × flooding) • No loss in connectivity • Guaranteed no route-stretch • Simple leverage of existing code base, extensible • Performs well in all cases (including high mobility)

14. Next Step • MPR extension must be evaluated for OSPF on MANETs