[Openstack-operators] [openstack-dev] [neutron] neutron ipv6 radvd sends out link-local or nothing as def gw (L3 HA issue?)

Assaf Muller assaf at redhat.com
Mon Aug 20 11:49:36 UTC 2018


On Mon, Aug 20, 2018 at 6:06 AM, Tobias Urdin <tobias.urdin at binero.se> wrote:
> When I removed those ips and set accept_ra to 0 on the backup router:
>
> ip netns exec qrouter-0775785e-a93a-4501-917b-be92ff03f36a sysctl -w
> net.ipv6.conf.qr-7fad6b1b-c9.accept_ra=0
> ip netns exec qrouter-0775785e-a93a-4501-917b-be92ff03f36a sysctl -w
> net.ipv6.conf.qr-5be04815-68.accept_ra=0
> ip netns exec qrouter-0775785e-a93a-4501-917b-be92ff03f36a ip a l
> ip netns exec qrouter-0775785e-a93a-4501-917b-be92ff03f36a ip addr del
> 1111:4444:0:1:f816:3eff:fe66:dea8/64 dev qr-7fad6b1b-c9
> ip netns exec qrouter-0775785e-a93a-4501-917b-be92ff03f36a ip addr del
> 1111:4444:0:1:f816:3eff:fec3:85bd/64 dev qr-5be04815-68
>
> And enabled ipv6 forwarding on the active router:
> ip netns exec qrouter-0775785e-a93a-4501-917b-be92ff03f36a sysctl -w
> net.ipv6.conf.all.forwarding=1
>
> It started working again, I think this is an issue when disabling a router,
> change it to L3 HA and enable it again, so a bug?

Quite possibly. Are you able to find a minimal reproducer?

>
> Best regards
> Tobias
>
>
> On 08/20/2018 11:58 AM, Tobias Urdin wrote:
>
> Continuing forward, these patches should've fixed that
> https://review.openstack.org/#/q/topic:bug/1667756+(status:open+OR+status:merged)
> I'm on Queens.
>
> The two inside interfaces on the backup router:
> [root at controller2 ~]# ip netns exec
> qrouter-0775785e-a93a-4501-917b-be92ff03f36a cat
> /proc/sys/net/ipv6/conf/qr-7fad6b1b-c9/accept_ra
> 1
> [root at controller2 ~]# ip netns exec
> qrouter-0775785e-a93a-4501-917b-be92ff03f36a cat
> /proc/sys/net/ipv6/conf/qr-5be04815-68/accept_ra
> 1
>
> Perhaps the accept_ra patches does not apply for enable/disable or routers
> changing from a normal router to a L3 HA router?
> Best regards
>
> On 08/20/2018 11:50 AM, Tobias Urdin wrote:
>
> Ok, so the issue here seems to be that I have a L3 HA router with SLAAC,
> both the active and standby router will
> configure the SLAAC obtained address causing a conflict since both side
> share the same MAC address.
>
> Is there any workaround for this? Should SLAAC even be enabled for
> interfaces on the standby router?
>
> Best regards
> Tobias
>
> On 08/20/2018 11:37 AM, Tobias Urdin wrote:
>
> Forgot [neutron] tag.
>
> On 08/20/2018 11:36 AM, Tobias Urdin wrote:
>
> Hello,
>
> Note: before reading, this router was a regular router but was then disable,
> changed ha=true so it's now a L3 HA router, then it was enabled again.
> CC openstack-dev for help or feedback if it's a possible bug.
>
> I've been testing around with IPv6 and overall the experience has been
> positive but I've met some weird issue that I cannot put my head around.
> So this is a neutron L3 router with an outside interface with a ipv4 and
> ipv6 from the provider network and one inside interface for ipv4 and one
> inside interface for ipv6.
>
> The instances for some reason get's there default gateway as the ipv6
> link-local (in fe80::/10) from the router with SLAAC and radvd.
>
> (1111.2222 is provider network, 1111.4444 is inside network, they are masked
> so don't pay attention to the number per se)
>
> interfaces inside router:
> 15: ha-9bde1bb1-bd: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1450 qdisc noqueue
> state UNKNOWN group default qlen 1000
>     link/ether fa:16:3e:05:80:32 brd ff:ff:ff:ff:ff:ff
>     inet 169.254.192.7/18 brd 169.254.255.255 scope global ha-9bde1bb1-bd
>        valid_lft forever preferred_lft forever
>     inet 169.254.0.1/24 scope global ha-9bde1bb1-bd
>        valid_lft forever preferred_lft forever
>     inet6 fe80::f816:3eff:fe05:8032/64 scope link
>        valid_lft forever preferred_lft forever
> 19: qg-86e465f6-33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue
> state UNKNOWN group default qlen 1000
>     link/ether fa:16:3e:3b:8b:a5 brd ff:ff:ff:ff:ff:ff
>     inet 1.2.3.4/22 scope global qg-86e465f6-33
>        valid_lft forever preferred_lft forever
>     inet6 1111:2222::f/64 scope global nodad
>        valid_lft forever preferred_lft forever
>     inet6 fe80::f816:3eff:fe3b:8ba5/64 scope link nodad
>        valid_lft forever preferred_lft forever
> 1168: qr-5be04815-68: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1450 qdisc
> noqueue state UNKNOWN group default qlen 1000
>     link/ether fa:16:3e:c3:85:bd brd ff:ff:ff:ff:ff:ff
>     inet 192.168.99.1/24 scope global qr-5be04815-68
>        valid_lft forever preferred_lft forever
>     inet6 fe80::f816:3eff:fec3:85bd/64 scope link
>        valid_lft forever preferred_lft forever
> 1169: qr-7fad6b1b-c9: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1450 qdisc
> noqueue state UNKNOWN group default qlen 1000
>     link/ether fa:16:3e:66:de:a8 brd ff:ff:ff:ff:ff:ff
>     inet6 1111:4444:0:1::1/64 scope global nodad
>        valid_lft forever preferred_lft forever
>     inet6 fe80::f816:3eff:fe66:dea8/64 scope link
>        valid_lft forever preferred_lft forever
>
> I get this error messages in dmesg on the network node:
> [581085.858869] IPv6: qr-5be04815-68: IPv6 duplicate address
> 1111:4444:0:1:f816:3eff:fec3:85bd detected!
> [581085.997497] IPv6: qr-7fad6b1b-c9: IPv6 duplicate address
> 1111:4444:0:1:f816:3eff:fe66:dea8 detected!
> [581142.869939] IPv6: qr-5be04815-68: IPv6 duplicate address
> 1111:4444:0:1:f816:3eff:fec3:85bd detected!
> [581143.182371] IPv6: qr-7fad6b1b-c9: IPv6 duplicate address
> 1111:4444:0:1:f816:3eff:fe66:dea8 detected!
>
> radvd:
> interface qr-7fad6b1b-c9
> {
>    AdvSendAdvert on;
>    MinRtrAdvInterval 30;
>    MaxRtrAdvInterval 100;
>
>    AdvLinkMTU 1450;
>
>    RDNSS  2001:4860:4860::8888  {};
>
>    prefix 1111:4444:0:1::/64
>    {
>         AdvOnLink on;
>         AdvAutonomous on;
>    };
> };
>
> inside instance:
> ipv4 = 192.168.199.7
> ipv6 = 1111:4444:0:1:f816:3eff:fe29:723d/64 (from radvd SLAAC)
>
> I can ping ipv4 gateway 192.168.199.1 and internet over ipv4.
> I can ping ipv6 gateway 1111:4444:0:1::1 but I can't ping the internet
>
> checking the ipv6 routing table on my instance I either get no default
> gateway at all or I get a default gateway to a fe80::/10 link-local address.
> IIRC this worked before I changed the router to a L3 HA router.
>
> Appreciate any feedback!
>
> Best regards
> Tobias
>
>
>
>
>
>
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