On 2012-02-14 13:42, Dave CROCKER wrote:
>
>
> On 2/13/2012 4:38 PM, Brian E Carpenter wrote:
>> There were very specific reasons why this was not done.
>
> Is there a useful citation that covers this strategic decision?
You may recall that at the time, we were very concerned about the
pre-CIDR growth rate in BGP and there was, iirc, a generalised
aversion to anything that would import the entire IPv4 BGP4 table
into IPv6. I don't recall without a lot of archive grepping whether
this was explicit in the IPng decision or whether it came a bit later.
>
> Given that that decision was an essential part of what caused a roughly
> 15 year delay, it would be helpful to have it documented.
>
>
>> And it doesn't
>> change the fact that an old-IP-only host cannot talk to a new-IP-only
>> host
>> without a translator. It is that fact that causes our difficulties today.
>
> The translator needed today is a complete gateway between two entirely
> incompatible protocols. The one that I'm describing would have been a
> trivial re-formatter.
>
> The development, deployment and interoperability differences between
> these is massive.
Honestly, having had an MSc student who benchmarked translation vs
application proxying vs native, I don't think so. The mechanics of
packet translation are trivial. The hard part is exactly the same as
with NAT44, caused by the shortage of IPv4 addresses and all the state
that goes with sharing the pool of transport ports for a single address.
On 2012-02-14 13:49, Randy Bush wrote:
> i guess you forget the discussion of variable length. i hope we don't
> have to rehash it here.
I haven't forgotten. The worst row I ever had at an IETF meeting was
on that topic.
> decisions were made. some were quite bad. v6 had some real zingers.
> remember tla/nla? no feature parity, such as dhcp (a war which has not
> finished)? it is almost as if it was designed to fail.
DHCP for v4 was still wet behind the ears at that time, so this
wasn't as obvious then as it is now; there's a bit of 20/20 hindsight
here. But yes, we could of course have done better. Unfortunately my
time machine is broken.
Brian
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