North American Network Operators Group

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Re: Going dual-stack, how do apps behave and what to do as an operator (Was: Apple Airport Extreme IPv6 problems?)

  • From: Iljitsch van Beijnum
  • Date: Wed Sep 19 10:13:46 2007

On 19-sep-2007, at 11:58, <[email protected]> <[email protected]> wrote:

Are you saying that 6to4 relay servers should be dedicated to that task?

No, of course not. However, even though today IPv6 traffic is fairly minimal for pretty much everyone, it has the potential to grow quickly now that more stuff comes with IPv6 support out of the box. If someone then adds an AAAA record to a service that generates a lot of traffic, a noticeable amount of traffic can move from IPv4 to IPv6 over night.

So I wouldn't be comfortable doing any form of IPv6 that is limited to, say, 200 Mbps on a router that can handle many gigabits worth of IPv4 traffic. That way, if more than a few percent of the traffic moves from IPv4 to IPv6, you're in trouble.

Note that this equally applies to tunnel en/decapsulation and regular IPv6 forwarding if those are not hardware accelerated.

However, if you have a box that has the same IPv6 as IPv4 capabilities, you won't have any trouble. And if you have a somewhat limited box handle IPv6 and then IPv6 grows beyond the capabilities of that box, at least your IPv4 traffic isn't affected.

I.e. you should either dedicate a pair of routers per PoP or set up a
couple of BSD/Linux boxes per PoP?

No need to do tunneling at leaf nodes (i.e., ones where all the traffic goes into one direction) and if you have at least two in your network one location can be backup for another, so then one per location would be enough. If I had some old 7200s lying around I'd use those, in locations where replacing drives isn't a huge deal a BSD box (Linux if you insist) would be a good choice because they give you a bigger CPU for your money.

But doing it on non-dedicated routers is fine as well as long as you're sure an excess of IPv6 traffic isn't going to cause problems.