Hi all,
I’m setting up a testbed virtualization server for a research group here. The
architecture is that I’m using Open vSwitch (1.10.90) and have a bridge (named
ovsbr0) that is attached to an OpenFlow controller (in our case, Floodlight
v0.90.) I then have instantiated two OVS “fake bridges” to provide automatic
VLAN tagging (vl10-ovsbr0 -> tag “10”, vl20-ovsbr0 -> tag “20”) to libvirt
networks that are defined around the two fake bridges. The upshot of all of
this so far is that I can instantiate a VM thru “virt-manager”, set the NIC of
the VM to use either “10-net” or “20-net”, and the VMs get a port on the
correct fake bridge, and their “vnet#” port gets tagged with the correct VLAN
tag.
So now I would like to provide DHCP (and DNS) to these VMs, but have different
DHCP IP address pools for each fake bridge (= libvirt network.) I have read
that libvirt can not assign IPs to the networks itself if the forward mode is
“bridge”. So I attempted to do this with dnsmasq running on the host system,
and configured it to only listen to the vl10-ovsbr0 interface (which I thought
would restrict the DHCP service to only that one fake bridge.) Sure enough, VMs
I instantiated and attached to the “10-net” did get a DHCP-assigned address
(192.168.10.x). Then I spun up another VM and attached it to the “20-net” and
was expecting it to not get assigned an IP address (since there was ostensibly
no DHCP service for that network) but to my surprise, the VM *did* get a DHCP
address assigned, from the pool I established for the “10-net”! This obviously
is not what I want. Now I’m wondering how this worked, and if I can fix it.
Here’s my OVS setup at present:
# ovs-vsctl show
3e0d861b-efb7-46b1-af1b-4a76cd833558
Bridge "ovsbr0"
Controller "tcp:127.0.0.1:6633"
is_connected: true
Port "ovsbr0"
Interface "ovsbr0"
type: internal
Port "vnet0"
tag: 10
Interface "vnet0"
Port "vnet1"
tag: 10
Interface "vnet1"
Port "vl10-ovsbr0"
tag: 10
Interface "vl10-ovsbr0"
type: internal
Port "vl20-ovsbr0"
tag: 20
Interface "vl20-ovsbr0"
type: internal
Port "vnet2"
tag: 20
Interface "vnet2"
# ovs-vsctl list-br
ovsbr0
vl10-ovsbr0
vl20-ovsbr0
# ovs-vsctl --real list-br
ovsbr0
# ovs-vsctl --fake list-br
vl10-ovsbr0
vl20-ovsbr0
# ovs-vsctl list-ports vl10-ovsbr0
vnet0
vnet1
# ovs-vsctl list-ports vl20-ovsbr0
vnet2
Here’s the config stanzas in my dnsmasq.conf file:
interface=vl10-ovsbr0
bind-interfaces
dhcp-range=192.168.10.50,192.168.10.150,4h
(also, tried changing the “interface=vl10-ovsbr0” stanza to
“listen-address=192.168.10.254” which is the IP addr I assigned the vl10-ovsbr0
int in Linux, but that didn’t work to fix the problem either...)
Anyone have any ideas on how to get the two fake bridges to have separate DHCP
service?
Thanks,
Will_______________________________________________
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