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Ghosts of Unix past, part 3: Unfixable designsGhosts of Unix past, part 3: Unfixable designsPosted Nov 19, 2010 1:15 UTC (Fri) by dlang (✭ supporter ✭, #313)In reply to: Ghosts of Unix past, part 3: Unfixable designs by Cato Parent article: Ghosts of Unix past, part 3: Unfixable designs
that sounds like something that was a really big deal when IPv6 was created, but with the increased processor speeds we have now, not nearly as important.
this isn't just that clock speeds are higher, but that the ratio of clock speeds to the system bus speeds is no longer 1:1, this means that it's possible to execute far more steps without slowing the traffic down.
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Ghosts of Unix past, part 3: Unfixable designs Posted Nov 19, 2010 11:15 UTC (Fri) by job (guest, #670) [Link]
If you're switching IP in hardware, it makes your design simpler and faster.
Ghosts of Unix past, part 3: Unfixable designs Posted Nov 19, 2010 11:41 UTC (Fri) by Cato (subscriber, #7643) [Link]
IP routers have not done CPU-based forwarding as the main path for a long time - the largest one is probably the Cisco CRS-3 which forwards 322 terabits per second when fully scaled (http://newsroom.cisco.com/dlls/2010/prod_030910.html), but even quite low end routers now also use hardware forwarding (i.e. ASICs, network processors, etc, not CPU).
You can probably manage to forward anything in hardware, but it helps somewhat that IPv6 has a regular header design.
IPV6 and hardware-parseable IP headers Posted Nov 19, 2010 23:26 UTC (Fri) by giraffedata (subscriber, #1954) [Link] I don't think CPU speed per se (how fast a single CPU is) is relevant. It's all about cost, since most IP networks are free to balance the number of CPUs, system buses, network links, etc.And from what I've seen, as the cost of routing in a general purpose CPU has come down, so has the cost of doing it in a specialized network link processor (what we're calling "hardware" here) -- assuming the IP header structure is simple enough. So today, as ten years ago, people would rather do routing in an ASIC than allocate x86 capacity to it. I think system designers balance system bus and CPU speed too, so it's not the case that there are lots of idle cycles in the CPU because the system bus can't keep up with it.
Ghosts of Unix past, part 3: Unfixable designs Posted Dec 3, 2010 9:05 UTC (Fri) by paulj (subscriber, #341) [Link]
FWIW, major router vendors still use software routing for many of their lower-end enterprise routers, even some mid-range.
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