Re: rules matching ipv6 prefix addrs

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On 11/04/2010 01:35 PM, Jeff Haran wrote:

Ideally, your ISP wouldn't do this to you. Ideally, they would advertise
the new prefix as preferred and deprecate the old one. So connections
using the old prefix would continue to work while new connections should
start using the new prefix. By the time the old prefix is invalid there
should be no TCP connections using it since most TCP connections don't
last as long as the valid lifetime. But since TCP doesn't define a
maximum connection duration, it's still a possibility that long lived
connections could be dropped, no matter how hard the ISP tries to
prevent it. But it does mean that any reasonable IPv6 firewall setup
should deal with multiple prefixes. And it also means that if you have
an application that won't well tolerate dropped connections, you should
probably code it to do a clean close and restart whenever the address at
your end of the socket transitions from preferred to deprecated state.


Ideally, yes, although I don't realistically believe that will happen. Now, to deal with multiple prefixes in parallel is even more complex than switching prefixes.

There is obviously no such thing as a maximum TCP duration, and therein lies a huge problem; the only way to deal with it sanely would have been to separate routing from endpoint identity, but the IPv6 architects chose to not go that route, partly because they seriously misestimated the timescale of the transition.

	-hpa
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