v6 & DSL / Cable modems [was: Private use of non-RFC1918 IP space
Iljitsch van Beijnum
iljitsch at muada.com
Thu Feb 5 13:59:43 CST 2009
On 5 feb 2009, at 20:06, Joe Abley wrote:
> 4) Obtain PA space and do what you're doing with v4.
> 5) Obtain PI space and do what you're doing with v4.
> (4) is problematic because filtering long prefixes in v6 seems to be
> more energetic than it is in v4. (5) is problematic if you don't
> qualify for PI space.
Better hope the RRG work (LISP, maybe) works out, then.
I'm sure some people will relax their filters but I'm also convinced
that a lot of people won't, at least not until a consensus on a good
prefix length filtering strategy emerges. The RIR policies are such
that if you allow /48s you're dead in the water if someone tries to
inject a large number of those on purpose or it happens by accident in
a particular unfortunate way.
The reason I think people won't accept long prefixes is because of the
above, or because (like me) they feel IPv6 PI was a mistake, or, the
main contributor to routing table bloat, laziness. And the reason they
won't care is that if an IPv6 destination returns !N applications that
try both IPv6 and IPv4 fall back on IPv4 without a noticeable delay so
outgoing sessions aren't affected. (Incoming sessions have to time out
though, no ICMPs back to the originator for those.)
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