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Re: Deploying IPv6 in a datacenter (Was: Awful quiet?)

  • From: Daniel Roesen
  • Date: Wed Dec 21 21:46:41 2005

On Wed, Dec 21, 2005 at 07:59:15PM -0600, Kevin Day wrote:
> I admit, my experiences are with only a tiny number of users, so I  
> may have just had bad luck. But, I had trouble finding any of our  
> IPv6 guinea pigs that didn't take a perceptibly slower route to us  
> over 6 than they do for 4. (50-100ms)

Well, yes, most v6 paths are still worse than the v4 paths. But there
are also counterexamples where the v6 paths are actually better than the
v4 paths. Happens when v6 is operated by techs and not under the belly
of peering politicians (yet). :-)

> Our test network was running through a GRE tunnel inside an IPIP  
> tunnel, so our MTU was abnormally tiny. I'm guessing that hit some  
> people with PMTUD problems that didn't normally see them because they  
> had a short MTU to start with.

Yep. MTU <1480 raises the chance to see PMTUD problems. E.g. using GRE
(1476) instead of IPIP (1480). Been there... :-)

> Out of all of our transit providers, only one could sell us IPv6  
> transit(not faulting those who don't yet). Out of 100+ peering  
> connections, only 2 wanted to do IPv6 peering. So, I don't have many  
> different angles to view things from.

Fair enough. But then it might make sense to make that more prominent.
Many folks will casually read your statement and think that it's a
generic one, instead of the view of a singlehomed customer with two
peerings. :-) On grand scale, US=>AP=>US=>EU is certainly _not_ the
standard anymore.

> I'll be writing up a paper going into a lot more detail about what  
> went right, what went wrong, and why the decision was made to revert  
> back to IPv4 soon, if anyone is interested.

Certainly! Please post this to the ipv6-ops[1] list too.

Best regards,


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