Hi Laine
What you have suggested sounds eminently reasonable. Thanks for your
advice. I'm going to give it a shot and report back.
Richard
On 11/27/19 1:38 PM, Laine Stump wrote:
On 11/26/19 11:07 PM, Richard Achmatowicz wrote:
Hello
I have a problem with attaching VMs to a VLAN interface.
Here is my setup: I have several physical hosts connected by a
physical switch. Each host has two NICs leading to the switch, which
have been combined into a team, team0. Each host a has a bridge br1,
which has team0 as a slave. So communication between hosts is based
on the IP address of bridge br1 on each host.
Up until recently, using libvirt and KVM, I was creating VMs which
had one interface attached the default virtual network and one
interface attached to the bridge:
virt-install ... --network network=default --network bridge=br1 ...
I would then statically assign an IP address to the bridge interface
on the guest when installing the OS.
A few days ago, a VLAN was introduced to split up the network. I
created a new VLAN interface br1.600 on each of the hosts. My initial
attempt was to do try this:
virt-install ... --network network=default --network bridge=br1.600 ...
which did not work. It then dawned on me that a VLAN interface and a
bridge aren't treated the same. So I started to look for ways to
allow my VMs to bind to this new interface.
This would seem to be a common situation. What is the best way to
work around this?
Both the host bridge and the host VLAN interface already have their
assigned IP addresses and appear like this in libvirt:
[root@clusterdev01 ]# ifconfig
br1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.0.110 netmask 255.255.255.0 broadcast
192.168.0.255
inet6 fe80::1e98:ecff:fe1b:276d prefixlen 64 scopeid
0x20<link>
ether 1c:98:ec:1b:27:6d txqueuelen 1000 (Ethernet)
RX packets 833772 bytes 2976958254 (2.7 GiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 331237 bytes 23335124 (22.2 MiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
br1.600: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.1.110 netmask 255.255.255.0 broadcast
192.168.1.255
inet6 fe80::1e98:ecff:fe1b:276d prefixlen 64 scopeid
0x20<link>
ether 1c:98:ec:1b:27:6d txqueuelen 1000 (Ethernet)
RX packets 189315 bytes 9465744 (9.0 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 302 bytes 30522 (29.8 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
[root@clusterdev01]# virsh iface-list --all
Name State MAC Address
---------------------------------------------------
br1 active 1c:98:ec:1b:27:6d
br1.600 active 1c:98:ec:1b:27:6d
[root@clusterdev01 sysadmin]# virsh iface-dumpxml br1.600
<interface type='vlan' name='br1.600'>
<protocol family='ipv4'>
<ip address='192.168.1.110' prefix='24'/>
</protocol>
<protocol family='ipv6'>
<ip address='fe80::1e98:ecff:fe1b:276d' prefix='64'/>
</protocol>
<link state='up'/>
<vlan tag='600'>
<interface name='br1'/>
</vlan>
</interface>
I tried following some suggestions which wrapped the vlan interface
in a bridge interface, but in ended up trashing the br1.600 interface
which was originally defined on the host.
Is there a failsafe way to deal with such a situation? Am I doing
something completely wrong here? In would like br1.600 to behave like
br1 .....
Any suggestions or advice greatly appreciated.
I guess what you need is for all the traffic from your guests to go
out on the physical network tagged with vlan id 600, and you want that
to be transparent to the guests, right?
The simplest way to handle this is to create a vlan interface off of
the ethernet that you have attached to br1 (not br1 itself), so it
would be named something like "eth0.600", and then create a new bridge
(call it, say "br600") and attach eth0.600 to br600. Then your guests
would be created with "--network bridge=br600"
(Note that Linux host bridges do now support vlan tagging (and maybe
even trunking) at the port level, but libvirt hasn't added support for
it. (in other words, "Patches Welcome!" :-))
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