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[Bug 1709115] Re: IPV6 only network DHCP Namespace missing default route

 

[Expired for neutron because there has been no activity for 60 days.]

** Changed in: neutron
       Status: Incomplete => Expired

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https://bugs.launchpad.net/bugs/1709115

Title:
  IPV6 only network DHCP Namespace missing default route

Status in neutron:
  Expired

Bug description:
  I noticed if I create an iPV6 only network using DHCPv6 stateful the
  qdhcp namespeace does not contain a default route to make recursive
  DNS requests possible as they need to route to external networks.

  The below shows what I see in the routing table of the qdhcp namespace
  with IPV6:

  # ip -6 ro
  XXXX:XXXX:9:9::/64 dev ns-e3832e4a-bd  proto kernel  metric 256  pref medium
  fe80::/64 dev ns-e3832e4a-bd  proto kernel  metric 256  pref medium
  #

  As we can see there is no default route so it is not possible to dns-
  masq to perform lookup:

  # ping6 2001:4860:4860::8844
  connect: Network is unreachable

  From within an instance on the same network/subnet if I set the
  resolv.conf to use the above external (google) ipv6 resolver I am able
  to reach it and get an address as expected as the route is getting set
  in the instance correctly.

  If we contrast this with IPv4 I can see a default route as shown below
  inside the qdhcp namespace:

  # ip -4 ro
  default via 172.16.0.1 dev ns-e3832e4a-bd
  172.16.0.0/24 dev ns-e3832e4a-bd  proto kernel  scope link  src 172.16.0.11
  #

  I find it very strange we are missing this default gateway for IPV6 in
  the qDHCP name space.

  I did some further testing and found this is also the case in the
  LBAAS (v2) name space - I can see that a packet ipv6 only request
  would route into the LBAAS name space, haproxy would proxy it onto the
  instance, the instance would respond to haproxy but then the
  connection would drop as the lbaas namespace does not contain the
  default route.

  This is on the newton release of neutron, if you need any further
  details just let me know and I will be happy to help.

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References