Virtualisation/KVM/Bridges bond vlans

Accueil	SysAdmin	Hobbies

QEMU - Configurer des bridges et des VLANs

Sites Références

Article très largement inspiré et adapté de ce site : [1]

Comment créer des bridges sur des bonds (avec ou sans VLANS) en utilisant NetworkManager (nmcli) ?

Some production systems you face might make use of bonded network connections that you need to bridge in order to get VMs onto them. That bond may or may not have a native VLAN (in which case you bridge the bond), or it might have VLANs on top (in which case you want to bridge the VLANs), or perhaps you need to do both.

Let’s walk through an example where we have a bond that has a native VLAN, that also has the tagged VLAN 123 on top (and maybe a second VLAN 456), all of which need to be separately bridged. This means we will have the bond (bond0) with a matching bridge (br-bond0), plus a VLAN on the bond (bond0.123) with its matching bridge (br-vlan123). It should look something like this.

Schéma d'infra

+------+   +---------+                           +---------------+
| eth0 |---|         |          +------------+   |  Network one  |
+------+   |         |----------|  br-bond0  |---| (native VLAN) |
           |  bond0  |          +------------+   +---------------+
+------+   |         |                                            
| eth1 |---|         |                                            
+------+   +---------+                           +---------------+
            | |   +---------+   +------------+   |  Network two  |
            | +---| vlan123 |---| br-vlan123 |---| (tagged VLAN) |
            |     +---------+   +------------+   +---------------+
            |                                                     
            |     +---------+   +------------+   +---------------+
            +-----| vlan456 |---| br-vlan456 |---| Network three |
                  +---------+   +------------+   | (tagged VLAN) |
                                                 +---------------+

To make it more complicated, let’s say that the native VLAN on the bond needs a static IP and to operate at an MTU of 1500 while the other uses DHCP and needs MTU of 9000.

OK, so how do we do that?

Start by creating the bridge, then later we create the interface that attaches to that bridge. When creating VLANs, they are created on the bond, but then attached as a slave to the bridge.

Create the bridge for the bond

First, let’s create the bridge for our bond. We’ll export some variables to make scripting easier, including the name, value for spanning tree protocol (SPT) and MTU. Note that in this example the bridge will have an MTU of 1500 (but the bond itself will be 9000 to support other VLANs at that MTU size.)

BRIDGE=br-bond0
BRIDGE_STP=yes
BRIDGE_MTU=1500

OK so let’s create the bridge for the native VLAN on the bond (which doesn’t exist yet).

nmcli con add ifname "${BRIDGE}" type bridge con-name "${BRIDGE}"
nmcli con modify "${BRIDGE}" bridge.stp "${BRIDGE_STP}"
nmcli con modify "${BRIDGE}" 802-3-ethernet.mtu "${BRIDGE_MTU}"

By default this will look for an address with DHCP. If you don’t want that you can either set it manually:

 nmcli con modify "${BRIDGE}" ipv4.method static ipv4.address 192.168.0.123/24 ipv6.method ignore

NOTE {{{contenu}}}