On Wed, Dec 31, 2008 at 5:27 PM, Christopher Morrow <[email protected]> wrote: > In 2005-ish at the IAB Workshop in AMS there was a good several > presenations on scaling/growth (one by Tony Li about hardware and why > moores-law doesn't apply to the gear in backbone networks).
Chris, I think I read that one. It was right before dram bandwidth took a sharp upward turn from something like 400mhz to I think 1600mhz today. Prior to that, it exhibited less than half the rate of change, increasing from 100 mhz in 1998 to 400 mhz in 2005. >> Assume a $2k COTS PC purchased 12/31/08 with component choice >> optimized for routing. > > you can't make this assumption as 2k cots devices can't forward at > +100gbps, a core backbone device today can, and do in several > networks. Sure I can. My $2k COTS PC can route 500mbps easily. Packet switching trivially parallelizes, so it follows that for no more than 200 times the price I can move 200 times the packets. This doesn't tell me what the actual cost would be, but it allows me to set an upper bound. >> Assume the ratio between BGP routes and updates per second will follow >> whatever growth pattern has been demonstrated in the ratio of routes >> to updates over the last 10 years. I expect this ratio is constant or >> near constant. > > it's actually not constant, there are a number of factors Whatever it is, we should be able to plot points from years past on a ratio to date graph and then fit a trend curve to it. >> How many routes can we pack in before we either fill memory, can no >> longer sustain both the 500mbps routing rate and keep up with BGP >> updates? Surely we can answer this question with engineering accuracy! > > One point Tony made was that soon, perhaps, you won't be able to make > a lookup across the memory device holding the FIB fast enough to > service a packet on the fastest known interfaces today, presuming the > FIB grows in memory at some set rate (look at the graphs Vince Fuller > or Geoff Huston have for approximations of the rates). If you can move packets across an interface at the given data rate then you can blindly multiplex and demultiplex packets from and to lower speed interfaces. This reduces the problem to one previously solved. There's doubtless a better solution but for conceptual purposes, that eliminates the data rate boundary condition as an active factor in the scalability assessment. Regards, Bill Herrin -- William D. Herrin ................ [email protected] [email protected] 3005 Crane Dr. ...................... Web: <http://bill.herrin.us/> Falls Church, VA 22042-3004 _______________________________________________ rrg mailing list [email protected] https://www.irtf.org/mailman/listinfo/rrg
