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" <ltd@interlink.com.au> To: "Alexei Roudnev" <alex@relcom.net> Cc: <nanog@nanog.org>; "Daniel Senie" <dts@senie.com> 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
packets on card rate and have other processing (with possible delays)
95% 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.