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

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 2

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 3

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

Opportunistic Path Vector Routing 5 User X ISP A ISP C ISP B 14 [5, A-B, 1-2-4, Mb/s, 20-30mins, $4] [5, A, 1-2, 15-30Mb/s, 15-30mins, $8] [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. path request [A-B-C, , 20Mb/s, 30mins] [A-C, 1-3-5, 10Mb/s, 15mins] Paths to 5 are found and ISP C sends replies to the user with two specific contract- path-vectors. reply [5, 10-30Mb/s, 15-45mins, $10]

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,  Alternative Approach: Parametric Gossip?  Flooding > Gossip > Random Walks  Sensor Networks, Vehicular Networks 6

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) 7 Opportunistic Path Vector Routing

Forwarding Mechanisms 8 Destination in Local Neighborhood PATH INQUIRY Bloom Filter Based Recursive Route Resolution YES NEXT HOP NO Smart Randomized Forwarding Parametric Gossiping Select a subset of neighbors 1)ISP Policy 2)Traffic Engineering 3)Pure Random Forward Path Inquiry

Forwarding Mechanisms 9 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

Forwarding Mechanisms 10 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

Evaluation CAIDA, AS-level, Internet Topology as of January 2010 (33,508 ISPs) Trial with 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 11

Results – Path Exploration 12 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

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

Results – Path Stretch 14

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

Results – Transmission Cost 16

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 17

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 18

Questions? Thank You For offline question: Google “Contract Switching” 19