IPv6

Fri Jun 13 04:48:18 UTC 2003

Thus spake "E.B. Dreger" <eddy+public+spam at noc.everquick.net>
> SS> When a 30Mpps IPv4 box falls back to <200kpps for IPv6, I
> SS> don't think "not completely functional" is an adequate
> SS> description.  To me, that falls into the "not supported"
> SS> category.
>
> Why not use the highest-order 32 bits of an IPv6 address for
> interdomain routing... i.e., "overlay" them on IPv4 addresses
> and/or a 32-bit ASN?  Yes, it smells of classful routing.  Call
> me shortsighted, but how many billion interdomain routing
> policies do we really need?

Most L3 switches shipping today (e.g. the product in question) have
particular ethertypes and destination address offsets hardcoded into their
ASICs.  It's not a matter of supporting 128-bit addresses -- they simply
doesn't understand IPv6's header any more than they do DECnet or AppleTalk.

While allocation policies may have an effect on how IPv6 FIBs are most
efficiently stored, address length is a fairly small part of the problem
when you're talking about redesigning every ASIC to handle both IPv4 and
IPv6.

S