1. Valiant Load-Balancing in Backbone Networks Rui Zhang-Shen rzhang@stanford.edu MS&E 319 — Feb 6, 2006

2. Backbone Networks: Observations A few tens of “core” nodes, Each aggregating traffic for a region, Interconnected by an increasingly rich mesh of long- haul optical trunks Robustness Load-balancing Low utilization—links over-provisioned for Uncertainty of traffic matrix the network is designed for Headroom for future growth Prepare to take over when links or routers fail Minimize congestion and delay variation Efficiency sacrificed for robustness and flexibility

3. Our Approach Assume we know or estimate the traffic entering and leaving each Regional Network Requires only local knowledge of users and market estimates Connect regional nodes by a logical full-mesh Use Valiant Load Balancing (VLB) over whole network Can support all traffic matrices Efficient use of capacity

4. Valiant Load-Balancing 1 2 3 N … 4 2 r r r r 2r/N 4