Adding physical Ethernet ports from non-root network namespace to OVS bridge

Question

I have an Ubuntu 20.04 server with four Ethernet interfaces: eno5, eno6, eno7, and eno8. The first two belong to the root netns, and the last two belong to a new netns called netns1. An ethernet cable physically interconnects eno6 with eno8.

I have created two OVS bridges (br0 and br1) like this:

sudo ovs-vsctl add-br br0
sudo ovs-vsctl add-port br0 eno7
sudo ovs-vsctl add-port br0 eno8
sudo ovs-vsctl add-br br1
sudo ovs-vsctl add-port br1 eno5
sudo ovs-vsctl add-port br1 eno6

I want to be able to ping from eno6 in br1 (10.0.0.6/24) to eno8 in br0 (10.0.0.8/24) by traveling through the ethernet cable rather than internally. According to this answer, this can be achieved by using separate network namespaces.

However, OVS complains that it cannot find eno7 and eno8, which are in the netns1 network namespace:

$ sudo ovs-vsctl show
7b1ef2bc-b596-4214-879e-144d45c6a8df
    Bridge br0
        Controller "tcp:10.98.1.85:6653"
            is_connected: true
        Port eno7
            Interface eno7
                error: "could not open network device eno7 (No such device)"
        Port eno8
            Interface eno8
                error: "could not open network device eno8 (No such device)"
        Port br0
            Interface br0
                type: internal
    Bridge br1
        Controller "tcp:10.98.1.85:6653"
            is_connected: true
        Port br1
            Interface br1
                type: internal
        Port eno6
            Interface eno6
        Port eno5
            Interface eno5
    ovs_version: "2.13.8"

Hence, my SDN controller is unable to discover the ports associated to eno7 and eno8 and I can't ping between 10.0.0.6 and 10.0.0.8.

This is what I have tried:

Creating the br0 bridge using "ip netns exec netns1" like this: sudo ip netns exec netns1 sudo ovs-vsctl add-br br0. There is no difference. br0 is still visible in the root namespace and adding eno7 and eno8 to br0 leads to the same error.
Manually adding br0 to the netns1 namespace like this: sudo ip link set br0 netns netns1. Now br0 is visible only in the netns1 namespace, however the error when adding eno7 and eno8 to the bridge is the same, regardless of whether I add them before or after setting br0 to the netns1 namespace.

I want to ask, is it possible to add ports from a custom network namespace to an ovs bridge? If so, how to proceed?

score 0 · Accepted Answer · answered Oct 05 '22 at 17:53

I want to be able to ping from eno6 in br1 (10.0.0.6/24) to eno8 in br0 (10.0.0.8/24) by traveling through the ethernet cable rather than internally. According to this answer, this can be achieved by using separate network namespaces.

Yes, but it's not the physical ports that must be in separate namespaces – it's about the interfaces that actually have the IP subnets configured on them. Normally they happen to be one and the same, but not when using any form of layered interfaces (bridges, bonds, vlans).

So just add eno7/eno8 to the bridge as normal, and then move br0 or br1 to a separate namespace.

Adding physical Ethernet ports from non-root network namespace to OVS bridge

1 Answers1