netdev - Re: [PATCH] ipv6: addrconf: clear IPv6 addresses and routes when losing link

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Date:	Thu, 28 Oct 2010 15:50:13 -0700
From:	Maciej Żenczykowski <zenczykowski@...il.com>
To:	Lorenzo Colitti <lorenzo@...gle.com>
Cc:	netdev@...r.kernel.org, Brian Haley <brian.haley@...com>
Subject: Re: [PATCH] ipv6: addrconf: clear IPv6 addresses and routes when
 losing link

> It's random, but the random interface ID is a property of the
> interface, not of the address, and thus survives interface up/down:

Interesting, that actually means a link down/up will break the
temporary address lifetimes (reset them).

# uname -a
Linux nike 2.6.34.7-61.fc13.x86_64 #1 SMP Tue Oct 19 04:06:30 UTC 2010
x86_64 x86_64 x86_64 GNU/Linux

# echo --Dump--; ip -6 addr list dev eth0 secondary; echo --Down--; ip
link set eth0 down; echo --Dump--; ip -6 addr list dev eth0 secondary;
echo --Up--; ip link set eth0 up; echo --Dump--; ip -6 addr list dev
eth0 secondary; echo --Sleep30--; sleep 30; echo --Dump--; ip -6 addr
list dev eth0 secondary; echo --Sleep60--; sleep 60; echo --Dump--; ip
-6 addr list dev eth0 secondary; echo --Done--

--Dump--
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qlen 1000
    inet6 2620:0:1000:1301:ab:5938:64ce:ae20/64 scope global temporary dynamic
       valid_lft 604667sec preferred_lft 85667sec
--Down--
--Dump--
--Up--
--Dump--
--Sleep30--
--Dump--
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qlen 1000
    inet6 2620:0:1000:1301:ab:5938:64ce:ae20/64 scope global temporary dynamic
       valid_lft 604775sec preferred_lft 85775sec
--Sleep60--
--Dump--
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qlen 1000
    inet6 2620:0:1000:1301:ab:5938:64ce:ae20/64 scope global temporary dynamic
       valid_lft 604715sec preferred_lft 85715sec
--Done--

Notice that when the v6 temp address comes back (presumably after
receiving an RA) it comes back with fresh valid/preferred lifetimes,
instead of the already partially expired ones that we had before the
link went down.

I was already aware that v6 temp addresses didn't work all that well
with short RA timeouts, but it looks like the logic needs a bit more
tweaking...
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