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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: too many variables
Lincoln Dale wrote: >> I asked this question to a couple of folks: >> >> "at the current churn rate/ration, at what size doe the FIB need to >> be before it will not converge?" >> >> and got these answers: >> >> --------- jabber log --------- >> a fine question, has been asked many times, and afaik noone has >> provided any empirically grounded answer. >> >> a few realities hinder our ability to answer this question. >> >> (1) there are technology factors we can't predict, e.g., >> moore's law effects on hardware development > > Moore's Law is only half of the equation. It is the part that deals with route > churn & the rate at which those can be processed (both peer notification and > control-plane programming data-plane in the form of FIB changes). Moore's law just makes an observation that the transistor count feasible for a minimum cost component doubles every 24 months. It actually says nothing about the performance of those components or their speed. > Moore's Law almost has zero relevance to FIB sizes. It doesn't map to growth in > SRAM or innovations/mechanisms for how to reduce the requirements for SRAM > while growing FIB sizes. sram components are following their own trajectory and you can fairly easily at this point project how big a cam you'll be able to buy and what it's power consumption will be out a couple years from the products currently in your routers (which are for the most part not state of the art). That said, not all forwarding engines in line cards utilize ternary cams or srams so assumptions that involve sram and sram-like components being the only game in town for fib storage are dangerous. > > cheers, > > lincoln. > >
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