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Re: [RRG] Idea for shooting down




On Nov 28, 2007, at 6:18 AM, Tom Petch wrote:

I wonder about router capacity, that is that the Internet only works because routers are incredibly fast at 'parsing' IPv4 addresses and I think that that is the inherent nature of an IP address, rather than because ASICs have been optimised for that task. So what I wonder about is the speed of routers at the transition from s+x flat routing to the next level down, s+x-1; an alternative could be to put the equivalent of the AFI bits into the middle of an IPv6 address (howls of protest) with an IPv4 address in the lower order bits, so
preserving the single bit-structure to parse.


I can vouch that routers are incredibly fast at doing longest-match lookups because folks have put in incredible amounts of work into the ASICs. Yes, of course, it could be much, much worse, but doing longest-match can in no way be construed as 'simple' to implement in hardware.

That said, if we want to make forwarding plane changes (and all of the proposals that I've seen involve some changes somewhere ;-), making those changes in the ASICs is not unreasonable.

Tony

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