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[Bug 1888256] Re: Neutron start radvd and mess up the routing table when: ipv6_ra_mode=not set ipv6-address-mode=slaac

 

Thx for testing that and for the info that it works.
Based on Your last comment and on fact that this shouldn't work in other way in Neutron I'm going to close this bug now.
Feel free to reopen it if You think there is something more to do there.

** Changed in: neutron
       Status: New => Invalid

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https://bugs.launchpad.net/bugs/1888256

Title:
  Neutron start radvd and mess up the routing table when:
  ipv6_ra_mode=not set  ipv6-address-mode=slaac

Status in neutron:
  Invalid

Bug description:
  Hello!

  I would like to report a possible bug.
  We currently using Rocky with Ubuntu 18.04.
  We use custom ansible for deployment.

  We have a setup, where the upstream core Cisco nexus DC switches
  answers to RA-s. This works fine with a network, which we had for
  years (upgraded from kilo)

  Now, we made a new region, with new network nodes, etc. and the IPv6
  not works as in the old region.

  In the new region, we had this subnet:

  [PROD][root(cc1:0)] <~> openstack subnet show Flat1-subnet-v6
  +-------------------+------------------------------------------------------+
  | Field             | Value                                                |
  +-------------------+------------------------------------------------------+
  | allocation_pools  | 2001:738:0:527::2-2001:738:0:527:ffff:ffff:ffff:ffff |
  | cidr              | 2001:738:0:527::/64                                  |
  | created_at        | 2020-07-01T22:59:53Z                                 |
  | description       |                                                      |
  | dns_nameservers   |                                                      |
  | enable_dhcp       | True                                                 |
  | gateway_ip        | 2001:738:0:527::1                                    |
  | host_routes       |                                                      |
  | id                | a5a9991c-62f3-4f46-b1ef-e293dc0fb781                 |
  | ip_version        | 6                                                    |
  | ipv6_address_mode | slaac                                                |
  | ipv6_ra_mode      | None                                                 |
  | name              | Flat1-subnet-v6                                      |
  | network_id        | fa55bfc7-ab42-4d97-987e-645cca7a0601                 |
  | project_id        | b48a9319a66e45f3b04cc8bb70e3113c                     |
  | revision_number   | 0                                                    |
  | segment_id        | None                                                 |
  | service_types     |                                                      |
  | subnetpool_id     | None                                                 |
  | tags              |                                                      |
  | updated_at        | 2020-07-01T22:59:53Z                                 |
  +-------------------+------------------------------------------------------+

  As you can see, the address mode is SLAAC, the RA mode is: None.

  Checking from network node, we see the qrouter:

  [PROD][root(net1:0)] </home/ocadmin> ip netns exec qrouter-4ffa4f55-95aa-4ce1-b4f8-8bbb2f9d53e1 ip a
  1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
      link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
      inet 127.0.0.1/8 scope host lo
         valid_lft forever preferred_lft forever
      inet6 ::1/128 scope host
         valid_lft forever preferred_lft forever
  35: ha-5dfb8647-f7: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1450 qdisc noqueue state UNKNOWN group default qlen 1000
      link/ether fa:16:3e:1c:4d:8d brd ff:ff:ff:ff:ff:ff
      inet 169.254.192.3/18 brd 169.254.255.255 scope global ha-5dfb8647-f7
         valid_lft forever preferred_lft forever
      inet 169.254.0.162/24 scope global ha-5dfb8647-f7
         valid_lft forever preferred_lft forever
      inet6 fe80::f816:3eff:fe1c:4d8d/64 scope link
         valid_lft forever preferred_lft forever
  36: qr-a6d7ceab-80: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
      link/ether fa:16:3e:a1:7e:69 brd ff:ff:ff:ff:ff:ff
      inet 193.224.218.251/24 scope global qr-a6d7ceab-80
         valid_lft forever preferred_lft forever
      inet6 2001:738:0:527:f816:3eff:fea1:7e69/64 scope global nodad
         valid_lft forever preferred_lft forever
      inet6 fe80::f816:3eff:fea1:7e69/64 scope link nodad
         valid_lft forever preferred_lft forever

  If I check the running process on our net1 node, I got this:

  [PROD][root(net1:0)] </home/ocadmin> ps aux |grep radvd |grep 4ffa4f55-95aa-4ce1-b4f8-8bbb2f9d53e1
  neutron  32540  0.0  0.0  19604  2372 ?        Ss   júl02   0:05 radvd -C /var/lib/neutron/ra/4ffa4f55-95aa-4ce1-b4f8-8bbb2f9d53e1.radvd.conf -p /var/lib/neutron/external/pids/4ffa4f55-95aa-4ce1-b4f8-8bbb2f9d53e1.pid.radvd -m syslog -u neutron

  
  The specific radvd config:
  [PROD][root(net1:0)] </home/ocadmin> cat /var/lib/neutron/ra/4ffa4f55-95aa-4ce1-b4f8-8bbb2f9d53e1.radvd.conf
  interface qr-a6d7ceab-80
  {
     AdvSendAdvert on;
     MinRtrAdvInterval 30;
     MaxRtrAdvInterval 100;
     AdvLinkMTU 1500;
  };

  If I spin up an instance, I see this:

  debian@test:~$ ip a
  1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
      link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
      inet 127.0.0.1/8 scope host lo
         valid_lft forever preferred_lft forever
      inet6 ::1/128 scope host
         valid_lft forever preferred_lft forever
  2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
      link/ether fa:16:3e:71:ca:8d brd ff:ff:ff:ff:ff:ff
      inet 193.224.218.9/24 brd 193.224.218.255 scope global dynamic eth0
         valid_lft 86353sec preferred_lft 86353sec
      inet6 2001:738:0:527:f816:3eff:fe71:ca8d/64 scope global dynamic mngtmpaddr
         valid_lft 2591994sec preferred_lft 604794sec
      inet6 fe80::f816:3eff:fe71:ca8d/64 scope link
         valid_lft forever preferred_lft forever
  debian@test:~$ ip -6 route
  ::1 dev lo proto kernel metric 256 pref medium
  2001:738:0:527::/64 dev eth0 proto kernel metric 256 expires 2591990sec pref medium
  fe80::/64 dev eth0 proto kernel metric 256 pref medium
  default via fe80::f816:3eff:fea1:7e69 dev eth0 proto ra metric 1024 expires 251sec hoplimit 64 pref medium
  default via fe80::5:73ff:fea0:2cf dev eth0 proto ra metric 1024 expires 1790sec hoplimit 64 pref medium

  
  As you can see, I'v got two default routes, where the upper one is not ment to be there.

  Could you point out something I missed, or there are some kind of bug,
  which makes this?

  Thanks:
   Peter ERDOSI (Fazy)

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