Can you try to trigger the problem again, but grab logs like so:

service NetworkManager stop
/usr/sbin/NetworkManager --no-daemon --log-level=debug

and we'll see what's going on there? Thanks!

Created attachment 424296 [details]
/var/log/messages (with --log-level=debug)

I added --log-level=debug to the init script instead, hope that's no problem.  I'm attaching the content of /var/log/messages starting when NM was started and continuing until the connection was stable.

Tore

Jun 15 22:53:24 wrath NetworkManager[4102]: <debug> [1276635204.717822] [nm-system.c:223] sync_addresses(): (eth0): syncing addresses (family 10)
Jun 15 22:53:24 wrath NetworkManager[4102]: <debug> [1276635204.717858] [nm-system.c:276] sync_addresses(): (eth0): removing address '2001:16d8:ee47:0:230:1bff:febc:7f23/64'
Jun 15 22:53:24 wrath NetworkManager[4102]: <debug> [1276635204.717905] [nm-system.c:259] sync_addresses(): (eth0): ignoring IPv6 link-local address
Jun 15 22:53:24 wrath NetworkManager[4102]: <debug> [1276635204.717921] [nm-system.c:312] sync_addresses(): (eth0): adding address '2001:16d8:ee47::bbb6/0'
Jun 15 22:53:24 wrath avahi-daemon[1295]: Withdrawing address record for 2001:16d8:ee47:0:230:1bff:febc:7f23 on eth0.
Jun 15 22:53:24 wrath avahi-daemon[1295]: Registering new address record for fe80::230:1bff:febc:7f23 on eth0.*.
Jun 15 22:53:25 wrath NetworkManager[4102]: <info> Policy set 'System eth0' (eth0) as default for IPv4 routing and DNS.
Jun 15 22:53:25 wrath NetworkManager[4102]: <info> Policy set 'System eth0' (eth0) as default for IPv6 routing and DNS.
Jun 15 22:53:25 wrath NetworkManager[4102]: <debug> [1276635205.748807] [nm-ip6-manager.c:756] netlink_notification(): netlink notificate type 21
Jun 15 22:53:25 wrath NetworkManager[4102]: <debug> [1276635205.748826] [nm-ip6-manager.c:472] process_addr(): processing netlink new/del address message
Jun 15 22:53:25 wrath NetworkManager[4102]: <debug> [1276635205.748945] [nm-ip6-manager.c:784] netlink_notification(): (eth0): syncing device with netlink changes
Jun 15 22:53:25 wrath NetworkManager[4102]: <debug> [1276635205.748958] [nm-ip6-manager.c:349] nm_ip6_device_sync_from_netlink(): (eth0): syncing with netlink (ra_flags 0x800000F0) (state/target 'got-address'/'got-address')
Jun 15 22:53:25 wrath NetworkManager[4102]: <debug> [1276635205.749018] [nm-ip6-manager.c:368] nm_ip6_device_sync_from_netlink(): (eth0): netlink address: fe80::230:1bff:febc:7f23
Jun 15 22:53:25 wrath NetworkManager[4102]: <debug> [1276635205.749070] [nm-ip6-manager.c:390] nm_ip6_device_sync_from_netlink(): (eth0): addresses synced (state got-address)
Jun 15 22:53:25 wrath NetworkManager[4102]: <debug> [1276635205.749582] [nm-ip6-manager.c:401] nm_ip6_device_sync_from_netlink(): router advertisement deferred to DHCPv6
Jun 15 22:53:25 wrath NetworkManager[4102]: <debug> [1276635205.749595] [nm-ip6-manager.c:442] nm_ip6_device_sync_from_netlink(): (eth0): RA-provided address no longer valid
Jun 15 22:53:25 wrath NetworkManager[4102]: <info> (eth0): device state change: 8 -> 9 (reason 5)
Jun 15 22:53:25 wrath NetworkManager[4102]: <warn> Activation (eth0) failed.

So this looks like the address '2001:16d8:ee47::bbb6/0' gets added to the interface, which is supposed to be the address from DHCP.  I'm a bit worried about the '0' there, but on a closer look that may be harmless.

But then just a second later that address is not present on the interface; during nm_ip6_device_sync_from_netlink() all of the interface's IP addresses are printed out and that address isn't there...  Need some more investigation.

Created attachment 430256 [details]
Random disconnection happening on wireless LAN

I've got this problem happening on my laptop, too.  (Or perhaps it could be a separate issue?)  Attaching the debug log (it's quite large as it took some time before it happened.  Looking at it, I see it happening here:


Jul  8 09:05:17 envy NetworkManager[4545]: <debug> [1278572717.1868] [nm-ip6-manager.c:252] rdnss_expired(): (wlan0): IPv6 RDNSS information expired
Jul  8 09:05:17 envy NetworkManager[4545]: <debug> [1278572717.1932] [nm-ip6-manager.c:286] set_rdnss_timeout(): (wlan0): removing expired RA-provided nameserver 2001:16d8:ee47::
Jul  8 09:05:17 envy NetworkManager[4545]: <info> (wlan0): device state change: 8 -> 9 (reason 5)

Perhaps packet loss on the WLAN (I was running a yum upgrade at the time, so the bandwidth was saturated) made the ICMPv6 RA to become lost, and that there's a bug that makes NM tear down the entire connection (including IPv4 connectivity) if the RDNSS server expire?

Tore

We could make the timer for RDNSS longer, but if you don't have usable IPv6 nameservers, you don't really have full IPv6 connectivity...  and since we're supposed to honor the RDNSS timeout, I'm not entirely sure what to do here.  There's obviously still the issue of the IPv6 and IPv4 being tied together to a degree, but when the RDNSS info expires then we're really expected to clear that out.

Now, since an admin changing your DNS servers is a lot less likely than WLAN packet loss, perhaps we should increase the timeout before we really consider the RDNSS servers expired...

I think the RDNSS lifetime is supposed to be independent of the prefix lifetime.  By default radvd will announce a router lifetime of 1800s, a prefix lifetime of 86400 (preferred 14400), and RDNSS lifetime 600.  I think you can also add on several other RDNSSes and prefixes with completely different lifetimes.

IMHO, if the RDNSS expire it should be removed from resolv.conf but it should not interrupt other things like the configured IPv6 (or IPv4) addresses or routers.

However, in the case that a RDNSS expiry would bring the number of servers in resolv.conf down to zero, it could be wise to delay removing it until a new server is available (regardless of how it's been learnt).

Tore

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