RE: [lir-wg] Discussion about RIPE-261
- Date: Tue, 24 Jun 2003 20:51:07 -0700
Aleksi,
Agree with your posting below, which is one of the reasons vendors of
geeky hardware have stated that they can't guarantee they'll continue to
ride Moore's law (one of the other reasons being that the problem of
routing table growth tends to switch from memory/cpu usage to protocol
stability issues).
> These technologies are also way more complex than DRAM
> to begin with.
No argument here. Put a DRAM wafer and a CAM wafer side-by-side under a
microscope and you'll immediately realize this.
Michel.
> Aleksi Suhonen wrote:
Routers -- and especially L3-switch-routers -- tend to use content
addressable memory (CAM) or other such specialized architectures
instead of dynamic random access memory (DRAM) to store the
forwarding table on NICs. The production numbers of DRAM chips are
orders of magnitude larger than those of CAM chips, and the gap
is getting bigger. These technologies are also way more complex
than DRAM to begin with. This means that the same amount of memory
takes up a lot more silicon real estate which is exponentially
relative to chip cost.
Using just DRAM is not an option either because you cannot build
the whole Internet on small-to-medium size routers with slow line
cards. Some operators will always outgrow them and those operators
will be the ones who in the end dictate how things are done.
This doesn't actually have anything to do with my personal view
on routing table growth. I'm just saying that there is a real
technical reason to be worried about it. CAMs (et al.) are getting
larger every year of course but, to the best of my knowledge, they
are not doubling in size every year as per Moore's law. To quote
Frederick Brooks, I don't think there will be a silver bullet to
this problem.
