[Madlug] A piece of history
Dale W. Carder
dwcarder at fiftythree.org
Wed Jan 30 00:34:16 CST 2008
On Jan 29, 2008, at 3:06 PM, Timm Murray wrote:
> On Tuesday 29 January 2008 02:49:20 pm Marcin Antkiewicz wrote:
>> Somehow, it makes me thing that, if IPv6 didn't make it in 15 years,
>> while the Internet infrastructure only grew bigger, it should be
>> let die
>> (just as the OSI stack).
> The problem is that we absolutely need it for the Internet to continue
> working. As the usage of the IPv4 addresses grows, so does the
> strain on
> core routers. NAT isn't a long term solution to this problem, and
> comes with
> its own limitations.
There are sort of 2 separate issues: 1) running out of IP addresses,
and 2) size of core router tables.
#2 isn't really getting addressed in v6 yet either. Today the v4
DFZ[*] table size is ~245k routes. The main reasons for this bloat
are deaggrigation via multihoming, traffic engineering, and some
amount of misconfiguration.
The reason this problem is important is for high-speed routers to
forward packets, they need to be able to look up the packet
destinations very, very fast utilizing exotic hardware such as
TCAM or massively parallel processing Tree-Bitmap algorithm.
The v6 design sort of implies that the only routes in the v6 DFZ
should be ISP's, and you must get space delegated from your ISP's
IPv6 /32. If you have multiple ISP's, it was thought you could
use multiple addresses per host.
With the amount of multihoming in particular that has occurred in
the last 10 years, provider-independent IP space will probably
end up a reality in ipv6 for legitimate business reasons. The
above problem will not get solved with ipv6 as it was assumed
it would maybe a decade ago.
So, with IP address shortage "solved" by ipv6, there is much more
work to be done with the size of the routing tables.
 Default Free Zone, a term for "core" internet routers that
do not have a default route because they have full reachability
information to every AS (autonomous system, aka: IP address
holders like ISP's and companies with their own unique space)
via the BGP protocol.
While cool and very fast they are extremely power hungry,
dissipate a lot of heat, and more importantly for routers
going forward: too hard to reprogram as routes change on
 One of the biggest routers in the world has an ASIC on
each linecard with (188) 32-bit 250MHz CPUs with a pile of RAM
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