New subject: [libvirt-users] [libvirt] Problem with Open vSwitch and dnsmasq

Friday, 23 March 2012

Date: Thu, 22 Mar 2012 11:43:03 -0700
Subject: Re: [libvirt] Problem with Open vSwitch and dnsmasq
From: aatteka(a)nicira.com
To: dano1988(a)hotmail.it
CC: libvir-list(a)redhat.com; roberto.sassu(a)polito.it; paolo.smiraglia(a)polito.it;
dev(a)openvswitch.org

On Thu, Mar 22, 2012 at 11:11 AM, Daniele Milani <dano1988(a)hotmail.it&gt; wrote:

I think I could try the first solution. Can you explain me how do I create the port used
by dnsmasq?

For example, is it correct to execute 
# ovs-vsctl add-port virbr1 port2 tag=2
to create a port for the vLan whose tag is 2 named "port2"?

Try something like this:
ovs-vsctl add-port virbr1 port2 tag=2

ovs-vsctl set Interface port2 type=internal 
ifconfig port2 10.0.0.1
ifconfig port2 up
/usr/sbin/dnsmasq --strict-order --bind-interfaces --except-interface lo --listen-address
10.0.0.1 --dhcp-range 10.0.0.10,10.0.0.20
--dhcp-leasefile=/var/lib/libvirt/dnsmasq/vlan2.leases --dhcp-lease-max=253
--dhcp-no-override

Though I have not tested it...

I tried the configuration you suggest; and the request is now received by dnsmasq.
I executed:
ifconfig port2 192.168.100.128 netmask 255.255.255.0
ifconfig port2 up
/usr/sbin/dnsmasq --strict-order --bind-interfaces --except-interface lo
--listen-address 192.168.100.128 --dhcp-range 192.168.100.129,192.168.100.139
--dhcp-leasefile=/var/lib/libvirt/dnsmasq/vlan2.leases --dhcp-lease-max=11
--dhcp-no-override --log-queries --log-facilities=/path_to_my_file/my_file 
tailf /path_to_my_file/my_file

obtaining the following output:
dnsmasq-dhcp[]: DHCPDISCOVER(port2) 52:94:00:02:a7:1e
dnsmasq-dhcp[]: DHCPOFFER(port2) 192.168.100.129 52:94:00:02:a7:1e
...
dnsmasq-dhcp[]: DHCPDISCOVER(port2) 52:94:00:02:a7:1e
dnsmasq-dhcp[]: DHCPOFFER(port2) 192.168.100.129 52:94:00:02:a7:1e
...
Now I have a different problem: none DHCP Offer is sent by port2.

Do someone know why does it happen and what to do about it?

Thanks,
Daniele Milani
Daniele Milani

Date: Thu, 22 Mar 2012 10:54:21 -0700
Subject: Re: [libvirt] Problem with Open vSwitch and dnsmasq
From: aatteka(a)nicira.com
To: dano1988(a)hotmail.it

CC: libvir-list(a)redhat.com; roberto.sassu(a)polito.it

On Thu, Mar 22, 2012 at 6:10 AM, Daniele Milani <dano1988(a)hotmail.it&gt; wrote:

Dear all,
I have the following situation:
-I replaced the standard bridge driver with the Open VSwitch one;
-I started a NAT-network on Libvirt (bridge name virbr1);
-I started a Virtual Machine (VM1) on Libvirt, and I tagged his interface (vnet0) with
tag=2;

-if I run "# ovs-vsctl show" I obtain:

Bridge "virbr1"
        Port "vnet0"
            tag: 2
            Interface "vnet0"
        Port "virbr1-nic"

            Interface "virb1-nic"
        Port "virbr1"
            Interface "virbr1"
                type: internal

-the problem is that it is impossible to assign to VM1 an IP, because the dnsmasq daemon
does not accept the tagged DHCP Discover frame.

Does someone know if there is a way for dnsmasq to accept tagged frames through
"virbr1", and send a tagged DHCP Offer packet back to VM1?

I believe you would need to run dedicated dnsmasq process instance per each VLAN that you
have. By

default I guess dnsmasq runs on virbr1, hence it does not see the tagged traffic that
comes from vnet0.

You could try to:
add another port to that bridge with the same VLAN as VM has. And run a separate instance
of dnsmasq there; or

change the tag of virb1 port, but this might lead to other issues (e.g. then non-tagged
VMs will not get DHCP leases).
Perhaps someone else can suggest something easier...

Greetings,
Daniele Milani

--

libvir-list mailing list

libvir-list(a)redhat.com

https://www.redhat.com/mailman/listinfo/libvir-list

2024

2023

2022

2021

2020

2019

2018

2017

2016

2015

2014

2013

2012

2011

2010

Re: [libvirt-users] [libvirt] Problem with Open vSwitch and dnsmasq