Appliance Vs Software based routers

[nathan at atlasnetworks.us (Nathan Eisenberg)]

> They are all software based routers... It really shouldn't matter
> whether an Appliance Application (i.e. some routing program is running
> on a minimal runtime environment ) or a routing program is running as
> part of an OS or as an Application on an OS. It is all Software until
> it
> becomes silicon.
> 
> The only issue is how far off the metal you are and its not hardware
> based routing really until there is no OS, no development environment,
> no software involved right?

As has been pointed out, hardware/appliance/software can be a highly semantic issue, at least for some people.  OP seemed like a specific question couched in vague terms - I'd rather have a discussion about what OP was trying to accomplish than rehash "Vyatta as a BRAS".

What's specifically important is the distinction between an 'appliance' platform (like a MIPS or Cisco routing switch), and what I presume OP infers a 'software' platform to be (an x86 box running iptables or Quagga).  In that case, I would tell OP that the PCI/PCI-e bus architecture isn't built to handle the rampant interrupts (or polling) that a real routing/switching workload generates.  The bus controller is built/sized to pump data to and from a video card/IO controller/etc, not to ship Ethernet packets up to the CPU and back out again in 8 different directions.  On the other hand, moving packets between 8 interfaces is exactly what a routing switch like a Cisco 3750 is built to do.

So, I wanted to retrieve the values of 'software router' and 'appliance' from OP to see if that's where he was going.

Best Regards,
Nathan Eisenberg