IPv6 addresses not released when routes change

[Kevin Oberman]

At a recent networking conference an IPv6 hour took place where IPv6
only was available. It was an interesting experience. On the whole,
things worked well, but I hit one problem.

When I brought up my system, I associated with the main conference SSID
and received an IPv6 address prior to the IPv6 hour. Everything was
working fine. At the appointed time, all of the SSIDs for IPv4/IPv6 were
disabled. (No, I was not expecting that) and I re-associated with the
IPv6 only SSID, the interface retained the old address in a different
/64. It added the new address in a different /64, but did not remove the
old address, even though there was no router to it. 

Worse, it continued to originate connections with the old address as the
source. I had to manually delete the old address before I could open a
connection. 

I've been thinking about what software should handle this. It needs to
be some software that is aware that the router that assigned the the
prefix is no longer available. There is nothing wrong with an IPv6
interfaces having several active addresses, so you can't delete one
just because another is assigned.
-- 
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman at es.net			Phone: +1 510 486-8634
Key fingerprint:059B 2DDF 031C 9BA3 14A4  EADA 927D EBB3 987B 3751
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