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Re: [ppml] too many variables

  • From: Scott Whyte
  • Date: Mon Aug 13 21:47:21 2007
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On 8/13/07, Leo Bicknell <[email protected]> wrote:
> In a message written on Mon, Aug 13, 2007 at 02:29:14PM +0200, Eliot Lear wrote:
> > This assumes "the real problem" is CPU performance, where many have
> > argued that the real problem is memory bandwidth.  Memory doesn't track
> > Moore's Law.  Besides, Moore's Law isn't a law.  What's your Plan B?
> > This is where a lot of RRG/RAM work is going on right now.
>
> I think there are multiple problems with core routers.  However,
> the discussion here was about BGP being able to converge.  For that,
> the FIB is not important, there need be no routing plane.
>
> What sort of computer does it take to get 200 sessions at an exchange
> point and compute a FIB in a "reasonable" amount of time?  That's
> determined first by the implementation (algorithm) and second by
> the processor speed.  It may also be impacted due to the bandwidth
> between routers, although I'm skeptical that's an issue.
>
> [Why?  Let's say 10,000 routes per peer, and 50 peers all on a single
> giabit ethernet exchange.  Let's also put an upper bound of 512 bytes
> per route.  That's ~250Mbytes, or what, maybe 30 seconds?]
>
> It seems to me an off the shelf PC with a Core 2 Duo processor, 4
> gig of memory, and a gigabit ethernet port would be 1-2 orders of
> magnitude faster than what's currently in the routers.  Optimize
> for a multithreaded CPU, add a second and it would converge really
> fast.  My own experience is that zebra / quagga blow away the
> performance of any router out there as long as you don't ask them
> to install the routes in the kernel (which is really slow in a
> general purpose OS).

Pick a newly released Core 2 Duo.  How long will Intel be selling it?
How does that compare with getting it into your RP design, tested,
produced, OS support integrated, sold, and stocked in your depots?

-Scott

>
> Now, once the FIB is computed, can we push it into line cards, is
> there enough memory on them, can they do wire rate lookups, etc are
> all good questions and all quickly drift into specialized hardware.
> There are no easy answers at that step...
>
> --
>        Leo Bicknell - [email protected] - CCIE 3440
>         PGP keys at http://www.ufp.org/~bicknell/
> Read TMBG List - [email protected], www.tmbg.org
>
>