nanog mailing list archives
RE: virtual aggregation in IETF
From: Paul Francis <francis () cs cornell edu>
Date: Sun, 20 Jul 2008 13:37:56 -0400
So, if I get you right, you are saying that edge routers have fewer CPU requirements, and so ISPs can get away with software routers and don't care about FIB. At the same time, folks in the middle are saying that in any event they need to buy high-end routers, and so can afford to buy enough hardware FIB so they also don't care (much) about FIB growth. Are there any folks for whom this statement isn't working? PF
-----Original Message----- From: Joel Jaeggli [mailto:joelja () bogus com] Sent: Sunday, July 20, 2008 1:02 PM To: Adrian Chadd Cc: nanog () nanog org Subject: Re: virtual aggregation in IETF Adrian Chadd wrote:On Sun, Jul 20, 2008, Joel Jaeggli wrote:Not saying that they couldn't benefit from it, however on one handwehave a device with a 36Mbit cam on the other, one with 2GB of ram,whichone fills up first?Well, the actual data point you should look at is "160k odd FIB froma coupleyears ago can fit in under 2 megabytes of memory." The random fetch time for dynamic RAM is pretty shocking compared toL2cache access time, and you probably want to arrange your FIB to playwell withyour cache. Its nice that the higher end CPUs have megabytes and megabytes of L2cachebut placing a high-end Xeon on each of your interface processors isprobablyasking a lot. So there's still room for optimising for sensibly-speccedhardware.If you're putting it on a line card it's probably more like a RAZA XLR, more memory bandwith and less cpu relative to the say the intel arch approach. That said I think you're headed to high end again. It has been routinetly posited that fib growth hurts the people on the edge more than in the center. I don't buy that for the reason outlined in my original response. If my pps requirements are moderate my software router can carry a fib of effectively arbitrary size at a lower cost than carrying the same fib in cam.Of course, -my- applied CPU-cache clue comes from the act of parsingHTTP requests/replies, not from building FIBs. I'm just going off the papers I'veread on thesubject. :) Adrian
Current thread:
- virtual aggregation in IETF Paul Francis (Jul 20)
- Re: virtual aggregation in IETF Alain Durand (Jul 20)
- RE: virtual aggregation in IETF Paul Francis (Jul 20)
- Re: virtual aggregation in IETF Joel Jaeggli (Jul 20)
- Re: virtual aggregation in IETF Adrian Chadd (Jul 20)
- Re: virtual aggregation in IETF Joel Jaeggli (Jul 20)
- Re: virtual aggregation in IETF Adrian Chadd (Jul 20)
- Re: virtual aggregation in IETF Joel Jaeggli (Jul 20)
- RE: virtual aggregation in IETF Paul Francis (Jul 20)
- Re: virtual aggregation in IETF Joel Jaeggli (Jul 20)
- RE: virtual aggregation in IETF Paul Francis (Jul 21)
- Re: virtual aggregation in IETF Adrian Chadd (Jul 20)
- Re: virtual aggregation in IETF Robert E. Seastrom (Jul 21)
- Re: virtual aggregation in IETF Alain Durand (Jul 20)