CS 740: Advance Computer Networks Hand-out on Router Design 02/07/2007

ISLIP Scheduling Example

ISLIP (cont.)

What Limits Router Capacity? Approximate power consumption per rack Power density is the limiting factor today

Multi-rack Routers Reduce Power Density Crossbar Linecards Switch Linecards

Question Instead, can we use an optical fabric at 100Tb/s with 100% throughput? Conventional answer: No Need to reconfigure switch too often 100% throughput requires complex electronic scheduler.

If Traffic is Uniform… R R R/N In Out R R In R In

Two-stage Load-Balancing Switch R R R In R/N Out R/N Out R/N R/N R/N R/N R R/N R/N R R In Out R/N R/N R/N R/N R/N R/N R R R R/N R/N In R/N R/N Load-balancing stage Switching stage 100% throughput for weakly mixing, stochastic traffic [C.-S. Chang, Valiant]

In Out In In R R 1 R R 2 R R 3 3 3 3 R/N R/N R/N R/N R/N R/N R/N R/N

Passive and Almost Zero Power Static WDM Switching A, A, A, A B, B, B, B C, C, C, C D, D, D, D 4 WDM channels, each at rate 2R/N Array Waveguide Router (AWGR) Passive and Almost Zero Power A In Out A, B, C, D In Out B In Out C D In Out

100 Tb/s router: Linecard Dataflow 2 2 l1, l2,.., lN R WDM R lN WDM l1 lN R l1, l2,.., lN 2 1 3 1 1 1 1 2 3 4 R WDM l1 lN l1, l2,.., lN Out 1 1 1 1 1