[106309] in North American Network Operators' Group
Re: Software router state of the art
daemon@ATHENA.MIT.EDU (William Herrin)
Sat Jul 26 09:36:11 2008
Date: Sat, 26 Jul 2008 09:35:59 -0400
From: "William Herrin" <herrin-nanog@dirtside.com>
To: "Dorn Hetzel" <dhetzel@gmail.com>
In-Reply-To: <2ee691ff0807260441u79c2fef0p76bec3bae85792fd@mail.gmail.com>
Cc: nanog list <nanog@merit.edu>
Errors-To: nanog-bounces@nanog.org
On Sat, Jul 26, 2008 at 7:41 AM, Dorn Hetzel <dhetzel@gmail.com> wrote:
> Ok, it's probably a stupid question, but given the relative ease of putting
> 4gb+ ram on a 64bit platform,
> could packet per second performance be improved by brute forcing the route
> lookup as an array of 1 byte destination interface indexes for a contiguous
> swath of /32's from bottom to top?
>
> Route updates would be a little ugly, 2^24 bytes to rewrite for a /8, but
> forwarding lookups out to be a single indexed read ?
Dorn,
In theory with about 6 gigs of ram for the IPv4 FIB, sure. But:
You're significantly multiplying the likelihood of a cache miss when
performing a lookup. You can do a fair amount of tree traversal in
cache for the price of one miss.
You're a tad shy on ram to try this with IPv6.
Regards,
Bill Herrin
--
William D. Herrin ................ herrin@dirtside.com bill@herrin.us
3005 Crane Dr. ...................... Web: <http://bill.herrin.us/>
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