A CIDR Prefix Stopping Rule for Topology Discovery

1. Benoit Donnet joint work with Timur Friedman Algotel 2005 – Presqu'Ile de Giens A CIDR Prefix Stopping Rule for Topology Discovery

2. Context • Network measurement • Internet topology discovery using distributed traceroute monitors • IP interface level • Existing tools: • Skitter (CAIDA) • TTM (RIPE NCC) • AMP (NLANR) • DIMES (Tel Aviv U.)

3. Scaling Problem • More monitors means more load on • network resources • destinations • Classical approaches either • stay small (skitter, TTM, AMP) • trace slowly (DIMES) • Can we trace more efficiently?

4. Contributions • Efficient topology discovery algorithm [Sigmetrics2005] • Doubletree • Communication overhead reduction • Stopping rule based on CIDR prefixes

5. Doubletree - Basics • Cooperative algorithm • Goal: avoiding paths already explored • Exploit tree-like structure of routes in the internet • from a monitor to a set of destinations • Backward probing (first suggested by Govindan et al.) • from a set of monitors to a destination • Forward probing and monitor coordination

6. Doubletree: Monitor-rooted tree

7. Doubletree: Destination-rooted tree

8. Doubletree: Probing scheme • Two probing schemes: • Backwards • Forwards • Stop sets = {(interface, root)} • Local Stop Set: B = {interface} • Global Stop Set: F = {(interface, destination)} • shared by monitors • Doubletree starts probing at some hop h from the monitor

9. Limitation • Communication cost • Global stop set exchange needs too high network resources • Up to 20.6MB for only 50,000 destinations

10. Destination based stopping rule

11. Solution • Communication cost reduction • Destination addresses aggregation through the use of CIDR prefixes • Global stop set of {(interface, prefix_destination)}

12. Solution (2)

13. Results (1)

14. Results (2)

15. Results (3)

16. Conclusion • Improvements to Doubletree • Communication cost reduced • Future Work • Implementation (traceroute@home) • BGP-guided topology discovery