Wresting Control from BGP: Scalable Fine-grained Route Control Patrick Verkaik, Dan Pei, Tom Scholl, Aman Shaikh , Alex C. Snoeren, Kobus van der Merwe UCSD / AT&T Labs contact: pverkaik@cs.ucsd.edu Motivation:BGP causes load imbalance We propose: route control using IRSCP (Intelligent Route Service Control Point) Typical BGP routing solution, hot-potato routing: Limitations of BGP BGP option 1: routers select single ISP-wide egress router Rest of the Internet Routers 2. IRSCP receives all egress routes from nearby customers and IRSCPs 1. Route control application measures the network and sends egress lists to IRSCP that avoid load imbalances Routes for customer ISP ISP Traffic to customer 4. #1 #2 Egress list for these three routers IRSCP IRSCP 4. 1. congestion! App Egress routes C 2. Routers pick nearest egress route Leads to load imbalance for C Potentially yielding congestion IRSCP 4. 4. Customer C 2. Achieves this routing solution BGP protocol controls ISP’s routing: BGP advertises C to routers Each router runs BGP decision process to select route to C Traffic follows reverse path along selected routes Below routing solution fixes the problem but unachievable in BGP Egress list contains egress routes ordered by preference 3. IRSCP runs decision process: for each router, IRSCP decision process picks most preferred (according to egress list) available egress route ISP C 4. IRSCP Informs nearby routers of its decision Achieved output rate Estimated max required input rate Performance of prototype IRSCP Connect to 40 emulated IRSCPs and 255 emulated (customer and ISP) routers Vary number of ISP routers and plot maximum sustained throughput Due to per-ISP-router decision process, more ISP routers means less throughput IRSCP easily keeps up with estimated required 95-percentile input rate To do: overcome bursts of maximum required input rate using flow control Achieved input rate Estimated 95 perc. required input rate ISP IRSCP App App IRSCP Network measurement BGP protocol Lists of egress routes