Hi,

I am using 12.04 and that particular sequence appears to be expected
behavior due to duplicate address detection in ipv6 leading to the ipv6
address being tentative.  I see similar behavior on an ethernet port
which has never physically been connected to anything.

Before attaching anything to the bridge, it has NO-CARRIER and tentative
ipv6 address, ping does not work:

$ ip addr show br0
26: br0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN 
    link/ether 00:16:3e:ff:00:01 brd ff:ff:ff:ff:ff:ff
    inet6 2605:2700:0:18::1/64 scope global tentative 
       valid_lft forever preferred_lft forever

After attaching something which is itself up:
$ ip addr show br0
26: br0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP 
    link/ether 00:16:3e:ff:00:01 brd ff:ff:ff:ff:ff:ff
    inet6 2605:2700:0:18::1/64 scope global 
       valid_lft forever preferred_lft forever
    inet6 fe80::216:3eff:feff:1/64 scope link 
       valid_lft forever preferred_lft forever

ping works at this point.

Furthermore, after removing the interface, NO-CARRIER is back but the
address is still no longer tentative and is still pingable:

$ ip addr show br0
26: br0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN 
    link/ether 00:16:3e:ff:00:01 brd ff:ff:ff:ff:ff:ff
    inet6 2605:2700:0:18::1/64 scope global 
       valid_lft forever preferred_lft forever
    inet6 fe80::216:3eff:feff:1/64 scope link 
       valid_lft forever preferred_lft forever
$ ping6 -c1 2605:2700:0:18::1
PING 2605:2700:0:18::1(2605:2700:0:18::1) 56 data bytes
64 bytes from 2605:2700:0:18::1: icmp_seq=1 ttl=64 time=0.047 ms

With 3.5.0-43-generic, I set net.ipv6.conf.all.dad_transmits and
net.ipv6.conf.all.accept_dad to 0 and that doesn't cause the addresses
to no longer be tentative. It seems like redhat may have had a similar
bug https://bugzilla.redhat.com/show_bug.cgi?id=709271 but it is not
clear what they did to fix it.  I have not yet tried more recent kernels
to see if the problem is fixed there.

** Bug watch added: Red Hat Bugzilla #709271
   https://bugzilla.redhat.com/show_bug.cgi?id=709271

-- 
You received this bug notification because you are a member of Ubuntu
Bugs, which is subscribed to Ubuntu.
https://bugs.launchpad.net/bugs/894272

Title:
  ipv6 broken for bridge

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/894272/+subscriptions

-- 
ubuntu-bugs mailing list
[email protected]
https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs

Reply via email to