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[Josie H <Josie.H@xxxxxxxxxxxxxx>]

Public bug reported:

Added a subnet as shown below.

neutron subnet-create HA1 fd5f:5d21:845:1e3c::/64 --name HA1SubnetIPv6
--no-gateway --host-route destination=::/0,nexthop=fd5f:5d21:845:1e3c::2
--allocation-pool
start=fd5f:5d21:0845:1e3c:ff00:0000:0042:0100,end=fd5f:5d21:0845:1e3c:ff00:0000:0042:0180
--ip-version 6

I wasn't necessarily expecting DHCP to work for IPv6, but it stopped working for IPv4.  In the log, I saw that the DHCP server had begun failing with the error:
http://paste.openstack.org/show/60638/

After a little digging in the code, I realised the DHCP agent was trying
to re-add an address (for the DHCP server) that already existed.  I'm
pretty sure the problem happens in init_l3 in interface.py, where
desired addresses are compared with existing addresses returned by "ip
addr show".  Since "show" returns IPv6 addresses in shortened form (i.e.
with unnecessary 0s removed), and the starting address I specified when
creating the subnet is unshortened, the comparison fails and the agent
tries to add the address again, which fails and causes the DHCP agent to
abort startup.

Of course, it's possible the failure to convert IPv6 addresses into
shortened form (or enforce entry only in shortened form) could have
other effects that I haven't observed.

Workaround: Specify all IPv6 addresses in shortened form when setting up
subnets.  The given Exception stops happening.  (Though I've
subsequently run into Bug 1257446 which also prevents dual-stack
operation.)

** Affects: neutron
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1266780

Title:
  DHCP server crashes on networks where IPv6 addresses were supplied
  unshortened

Status in OpenStack Neutron (virtual network service):
  New

Bug description:
  Added a subnet as shown below.

  neutron subnet-create HA1 fd5f:5d21:845:1e3c::/64 --name HA1SubnetIPv6
  --no-gateway --host-route
  destination=::/0,nexthop=fd5f:5d21:845:1e3c::2 --allocation-pool
  start=fd5f:5d21:0845:1e3c:ff00:0000:0042:0100,end=fd5f:5d21:0845:1e3c:ff00:0000:0042:0180
  --ip-version 6

  I wasn't necessarily expecting DHCP to work for IPv6, but it stopped working for IPv4.  In the log, I saw that the DHCP server had begun failing with the error:
  http://paste.openstack.org/show/60638/

  After a little digging in the code, I realised the DHCP agent was
  trying to re-add an address (for the DHCP server) that already
  existed.  I'm pretty sure the problem happens in init_l3 in
  interface.py, where desired addresses are compared with existing
  addresses returned by "ip addr show".  Since "show" returns IPv6
  addresses in shortened form (i.e. with unnecessary 0s removed), and
  the starting address I specified when creating the subnet is
  unshortened, the comparison fails and the agent tries to add the
  address again, which fails and causes the DHCP agent to abort startup.

  Of course, it's possible the failure to convert IPv6 addresses into
  shortened form (or enforce entry only in shortened form) could have
  other effects that I haven't observed.

  Workaround: Specify all IPv6 addresses in shortened form when setting
  up subnets.  The given Exception stops happening.  (Though I've
  subsequently run into Bug 1257446 which also prevents dual-stack
  operation.)

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