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Re: Scalability issues in the Internet routing system
Forwarding is in line cards not because of CPU issues, but because of BUS issues. It means, that card can be software based easily. Anyway, as I said - it is only small, minor engineering question - how to forward having 2,000,000 routes. If internet will require such router - it will be crearted easily. Today we eed 160,000 routes - and it works (line cards,m software, etc - it DO WORK). ----- Original Message ----- From: "Lincoln Dale" <email@example.com> To: "Alexei Roudnev" <firstname.lastname@example.org> Cc: <email@example.com>; "Daniel Senie" <firstname.lastname@example.org> Sent: Wednesday, October 26, 2005 2:42 AM Subject: Re: Scalability issues in the Internet routing system > > Alexei Roudnev wrote: > > You do not need to forward 100% packets on line card rate; forwarding 95% > > packets on card rate and have other processing (with possible delays) thru > > central CPU can work good enough.. > > heh. > in the words of Randy, "i encourage my competitors to build a router > this way". > > reality is that any "big, fast" router is forwarding in hardware - > typically an ASIC or some form of programmable processor. > the lines here are getting blurry again .. Moore's Law means that > packet-forwarding can pretty much be back "in software" in something > which almost resembles a general-purpose processor - or maybe more than > a few of them working in parallel (ref: > <http://www-03.ibm.com/chips/news/2004/0609_cisco.html>). > > if you've built something to be 'big' and 'fast' its likely that you're > also forwarding in some kind of 'distributed' manner (as opposed to > 'centralized'). > > as such - if you're building forwarding hardware capable of (say) 25M > PPS and line-rate is 30M PPS, it generally isn't that much of a jump to > build it for 30M PPS instead. > > i don't disagree that interfaces / backbones / networks are getting > faster - but i don't think its yet a case of "Moore's law" becoming a > problem - all that happens is one architects a system far more modular > than before - e.g. ingress forwarding separate from egress forwarding. > > likewise, "FIB table growth" isn't yet a problem either - generally that > just means "put in more SRAM" or "put in more TCAM space". > > IPv6 may change the equations around .. but we'll see .. > > > cheers, > > lincoln.