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[sean redmond <sean.redmond1@xxxxxxxxx>]

Public bug reported:

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.

** Affects: neutron
     Importance: Undecided
         Status: New

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

Title:
  IPV6 only network DHCP Namespace missing default route

Status in neutron:
  New

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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