North American Network Operators Group

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Re: Apple Airport Extreme IPv6 problems?

  • From: Iljitsch van Beijnum
  • Date: Sat Sep 15 16:22:34 2007

On 15-sep-2007, at 21:25, Barrett Lyon wrote:

The other thought that occurred to me, does FF/Safari/IE have any ability to default back to v4 if v6 is not working or behaving badly? This could be a helpful transition feature but may be more trouble than it's worth.

Browsers are pretty good at falling back on a different address in general / IPv4 in particular when the initial try doesn't work, but it does take too long if the packet is silently dropped somewhere. If there is an ICMP unreachable there is no real delay. Worst case is a path MTU discovery black hole, then browsers generally don't fall back.

For some reason, I can't reach the IETF or ARIN over IPv6 from home, which means every time I want to read an RFC I have to wait for my browser to time out and retry.

Apple's Mail is worse: it has a bug that prevents it from delivering mail with SMTP over IPv6, but it won't fall back to IPv4 so you need to intervene manually.

It would be good if more ISPs deployed 6to4 gateways so the 6to4 experience would be better. Windows Vista will also try to use 6to4 out of the box (but only if it has a public IPv4 address, can't do 6to4 from behind NAT).