On the Scalability of Path Exploration Using Opportunistic Path-Vector Routing

1. On the Scalability of Path Exploration Using Opportunistic Path-Vector Routing Hasan T. Karaoglu, Murat Yuksel, Mehmet H. Gunes University of Nevada, Reno ICC’11 NGNI, Kyoto June, 2011

2. Motivation • Rising Trends for Communication • Customizable – On Demand Network Services • Software Defined Networking (OpenFlow, IPSphere, GENI), Cognitive Radio, CDN, “Routing As a Service” • Multi-dimensional Routing Problem • Application specific (VPN, CDN), Economics – Value components, Security, Mobility, Energy-Aware • Dynamism (Mobility, Time Granularity) • Implications • Complexity & Scale Problems, Lack of Coordination

3. Research Question • These implied challenges have been considered before: Wireless & MANET & Complex Networks • “Can we apply some of the lessons learnt into Wired, Inter-domain Routing Area?” • Distributed Mechanisms • Loose Coordination • Relaxed Determinism • Dynamism and Diversity

4. Outline • Motivation • Research Question • Opportunistic Path Vector Routing • Routing Mechanisms • Evaluation • Improvements • Conclusion

5. Opportunistic Path Vector Routing [5, A, 1-2, 15-30Mb/s, 15-30mins, $8] [5, 10-30Mb/s, 15-45mins, $10] [5, A-B, 1-2-4, 15-20Mb/s, 20-30mins, $4] ISP B path request path request 2 reply reply [A-B-C, 1-2-4-5, 20Mb/s, 30mins] 1 4 ISP A User X reply 3 ISP C path request 5 [5, A, 1-3, 5-10Mb/s, 15-20mins, $7] Paths to 5 are found and ISP C sends replies to the user with two specific contract-path-vectors. Paths to 5 are found and ISP C sends replies to the user with two specific contract-path-vectors. [A-C, 1-3-5, 10Mb/s, 15mins]

6. Opportunistic Path Vector Routing • IETF - Path Computation Element (PCE) WG • GMPLS, Inter-domain QoS, (Nested LSP or LSP Stitching) • RFC 4655: Architecture, 5376: Reqs, 5441: BRPC • Path Discovery along given AS_PATH • Limited Scale, Computational and Storage Cost Problems • Solution Proposals • S. Secci et al., “AS-level source routing for multi-provider connection-oriented services” Computer Networks 54, 14 (October 2010) • F. Cugini et al., "PCE Communication Protocol for Resource Advertisement in Multi-Domain BGP-Based Networks“, OWL3, 2009. • Alternative Approach: Parametric Gossip? • Flooding > Gossip > Random Walks • Sensor Networks, Vehicular Networks

7. Opportunistic Path Vector Routing • Gossiping: Making distribution of path discovery packets a parametric probabilistic process • Parameters:Resource Availability, Risk Perception, Economic Concerns, ISP Policy, Overall Discovery Packet Traffic Load (Filtering) • Probabilistic Approach: Not Arbitrary, well-studied theoretical properties (Check Percolation Theory and Belief Propagation)

8. Forwarding Mechanisms YES Destination in Local Neighborhood Bloom Filter Based Recursive Route Resolution NEXT HOP PATH INQUIRY NO • Parametric Gossiping • Select a subset of neighbors • ISP Policy • Traffic Engineering • Pure Random • Forward Path Inquiry Smart Randomized Forwarding

9. Forwarding Mechanisms bTTL: How many copies of discovery packet will be made and forwarded? Provides caps on messaging cost. dTTL: Time to Live, Hop-Count Limit MAXFWD: Max. number of neighbors to be forwarded

10. Forwarding Mechanisms • Procedure to check if destination is within two-hop neighborhood • Bloom Filters: Efficient, Fast Group Membership Storage / Control Method for locality database • M Bloom Filter for M discovery region • False Positives result in Smart-Randomized Forwarding • Nice balance between locality storage cost and messaging cost of flooding

11. Evaluation • CAIDA, AS-level, Internet Topology as of January 2010 (33,508 ISPs) • Trial with 10000 ISP Pair (src,dest), 101 times • With various ISP cooperation / participation and packet filtering levels • NL: No local information used • L: Local information used (with various filtering) • With no directional and policy improvements for base case (worst) performance

12. Results – Path Exploration Over 80% path exploration success ratio even at 50% discovery packet filtering thanks to diversity of Internet routes. With Locality, OPVR achieves near 100 percent path exploration success. As budget increases with BTTL and MAXFWD, OPVR becomes robust to filtering

13. Results - Diversity Tens of paths discovered favoring multi-path routing and reliability schemes.

14. Results – Path Stretch

15. Results – Messaging Cost Number of discovery packet copies is well below theoretical bounds thanks to path-vector loop prevention.

16. Results – Transmission Cost

17. Conclusion • OPVR’s Messaging Based Query Methods can be a better option • Advantages: Distributed, Light-Computation • Disadvantages: Less deterministic, Message Cost • Gossiping Method: • Diverse Path Exploration, • Controllable Messaging Cost, • Robust to Filtering • Allows parametric, fine-grained policy definitions • Dynamic

18. Improvements • Directional Gossiping (P2P or P2M) • Structured AS Path Exploration • No-valley Rule • Cache • Similar to DNS cache • Business Alliances Model • Clusters of ISPs as business partners • Revisiting HLP model, customer cone

19. Questions? Thank You For offline question: karaoglu@cse.unr.edu Google “Contract Switching” http://www.cse.unr.edu/~yuksem/contract-switching.htm