[Openstack] [neutron]Why there is an extra router interface in the qrouter namespace in DVR mode?

Cody codeology.lab at gmail.com
Mon Aug 6 02:24:02 UTC 2018


I didn't realize that inline screenshots would be scrubbed. Below is a
re-edited version of my original post.

Cody

---
Hi folks,

I have a DVR-enabled cluster made of a controller, network, and
compute node. The agent_mode is set to dvr_snat on the network node
and dvr on the compute node. North-south traffic works fine in both
SNAT and the floating IP scenarios. The only thing I cannot explain is
the extra interface shown in the Horizon dashboard for tenant routers.
Here are details:

'ip netns' output on the compute node:

[root at compute ~]# ip netns
fip-eadd51b1-1b0a-4504-b694-4f54b7b60d3d (id: 1)
qrouter-b7570af0-42f6-499d-bbf0-2139a98bc0a3 (id: 0)

'ip addr show' from within the router namespace on the compute node:

[root at compute ~]# ip netns exec
qrouter-b7570af0-42f6-499d-bbf0-2139a98bc0a3 ip addr show
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: rfp-b7570af0-4: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc
noqueue state UP group default qlen 1000
    link/ether ca:08:94:69:b9:6c brd ff:ff:ff:ff:ff:ff link-netnsid 0
    inet 169.254.106.114/31 scope global rfp-b7570af0-4
       valid_lft forever preferred_lft forever
    inet6 fe80::c808:94ff:fe69:b96c/64 scope link
       valid_lft forever preferred_lft forever
13: qr-bd3e180e-2d: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1450 qdisc
noqueue state UNKNOWN group default qlen 1000
    link/ether fa:16:3e:c4:a8:3c brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.1/24 brd 192.168.0.255 scope global qr-bd3e180e-2d
       valid_lft forever preferred_lft forever
    inet6 fe80::f816:3eff:fec4:a83c/64 scope link
       valid_lft forever preferred_lft forever

Notice there is only one qr interface in the preceding output, but the
Horizon dashboard shows an extra interface for the same router:

Name                                    Fixed IPs
(bd3e180e-2dd6)                    192.168.0.1
(da7884d9-2ff1)                     192.168.0.5

My questions are where the interface (da7884d9-2ff1) comes from and
what it does. Thank you!

Cody





On Sun, Aug 5, 2018 at 7:55 PM Cody <codeology.lab at gmail.com> wrote:
>
> Hi folks,
>
> I have a DVR-enabled cluster made of a controller, network, and compute node. The agent_mode is set as dvr_snat on the network node, and dvr on the compute node. The north-south traffic works in both SNAT and the floating IP scenarios, but I cannot explain the extra interface shown up in the Horizon dashboard for every tenant router. More details as below:
>
> ip netns output on the compute node:
>
>
>
> ip addr show from within the router namespace on the compute node:
>
>
>
> *Notice there is only one qr interface, the gateway, for the tenant subnet.
>
> Here is the display from the Horizon dashboard router interface page:
>
>
> Do you see the extra interface (da7884d9-2ff1)? The only place I can find it is from inside the additional routing table in the router namespace:
>
>
>
>
> What does that extra interface come from and what is it for? Why does it show up in the dashboard, but not in the command line output?
>
> Thank you all in advance.
>
> Cody
>



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