IPv6 /64 links (was Re: ipv6 book recommendations?)

Wed Jun 13 01:13:51 UTC 2012

On Jun 12, 2012, at 4:24 PM, Masataka Ohta wrote:

> Tony Hain wrote:
> 
>> Note the ~ ...  And ARP requires media level broadcast, which ND does not.
> 
> Any multicast capable link is broadcast capable.

BZZT! but thank you for playing.

Many NBMA topologies support multicast.

> 
>> Not all media support broadcast.
> 
> A fundamental misunderstanding of people designed IPv6 is that
> they believed ATM not broadcast capable but multicast capable.
> 

This is, in fact, true.

Yes, you can synthesize ATM broadcast-like behavior, but it is not broadcast.

>>> As ND requires MLD and DAD, overhead in time when addresses are
>>> assigned is very large (several seconds or more if multicast is not very
>>> reliable), which is harmful especially for quicking moving mobile hosts.
>> 
>> So leveraging broadcast is why just about every implementation does a
>> gratuitous ARP-and-wait multiple times,
> 
> Not at all. IPv4 over something does not have to be ARP.
> 

IPv4 over anything requires some form of L2 address resolution in any case
where L2 addresses must be discovered.

> IPv6 is broken eventually requiring all link use ND, even
> though ND was designed for stational hosts with only Ethernet,
> PPP and ATM (with a lot of misunderstanding) in mind.
> 

Not really.

>> BS ... Broadcasts are dropped all the time,
> 
> On Ethernet, broadcast is as reliable as unicast.
> 

BS.

>> Just because you have never liked the design choices and tradeoffs made in
>> developing IPv6 doesn't make them wrong.
> 
> It is the ignorance on the end to end principle which makes
> IPv6 wrong.
> 

End-to-end is significantly more broken in IPv4 because of the need for NAT than it is in IPv6.

IIRC, you were the one promoting even more borked forms of NAT to try and compensate for this.

>> If there are constructive suggestions to make the
>> outcome better, take them to the IETF just like all the
>> constructive changes made to IPv4.
> 
> IPv6 is a proof that IETF has lost the power to make
> the world better.

IPv6 is quite a bit better than IPv4 in many ways. It could be better still, but, it is definitely superior
to current IPv4 implementations and vastly superior to the IPv4 implementations that existed when
IPv6 was designed.

Owen