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Instances don't get an IP from DHCP (Quantum, OVS, multi-node computes)

asked 2012-05-18 14:45:39 -0500

emilienm gravatar image


Since 2 weeks, I've been looking for a solution with a Quantum + OVS issue.

The situation :

2 servers :

Essex-1 - Eth0 : - ETH1 : connected to br-int OVS bridge -> Glance, Nova-*, Keystone, Horizon, Quantum-Server, KVM, OVS, Quantum-Agent -> nova.conf : (

Essex-2 - Eth0 : - ETH1 : connected to br-int OVS bridge -> nova-compute, KVM, Quantum-Agent -> nova.conf : (

I've followed ( and (

I've created th network with : nova-manage network create --label=mysql --fixed_range_v4= --project_id=d2f0dc48a8944c6e96cb88c772376f06 --bridge=br-int --bridge_interface=eth1

What's not working : -> When I create an instance from dashboard, the VM does not get an IP from DHCP server (hosted on ESSEX-1). You can see the logs here :

What I did to investigate : -> dhcpdump -i br-int : I can see DHCPDISCOVER on both servers (without answers) -> ps -ef | grep dnsmasq : nobody 6564 1 0 14:12 ? 00:00:00 /usr/sbin/dnsmasq --strict-order --bind-interfaces --conf-file= --domain=novalocal --pid-file=/var/lib/nova/networks/ --listen-address= --except-interface=lo --dhcp-range=,static,120s --dhcp-lease-max=256 --dhcp-hostsfile=/var/lib/nova/networks/nova-gw-0f427a46-3f.conf --dhcp-script=/usr/bin/nova-dhcpbridge --leasefile-ro root 6565 6564 0 14:12 ? 00:00:00 /usr/sbin/dnsmasq --strict-order --bind-interfaces --conf-file= --domain=novalocal --pid-file=/var/lib/nova/networks/ --listen-address= --except-interface=lo --dhcp-range=,static,120s --dhcp-lease-max=256 --dhcp-hostsfile=/var/lib/nova/networks/nova-gw-0f427a46-3f.conf --dhcp-script=/usr/bin/nova-dhcpbridge --leasefile-ro root 16536 6192 0 14:40 pts/14 00:00:00 grep --color=auto dnsm

Is my nova.conf correct ? What's wrong with my configuration ? Is there a problem with DNSMASQ ?

I would apreciate any idea !


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answered 2012-05-28 16:45:44 -0500

emilienm gravatar image

I update with my day work :

Now, my VMs hosted by ESSEX-1 have network, but VMs hosted by ESSEX-2 not.

root@essex-1:/var/lib/nova/networks# more nova-gw-fbbd1249-c5.conf fa:16:3e:5e:e2:f3,host-, fa:16:3e:34:bf:36,host-,

root@essex-2:~# tcpdump -i eth1 | grep DHCP tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on eth1, link-type EN10MB (Ethernet), capture size 65535 bytes 16:29:50.653177 IP > BOOTP/DHCP, Request from fa:16:3e:34:bf:36 (oui Unknown), length 300 16:29:53.315672 IP > BOOTP/DHCP, Request from fa:16:3e:34:bf:36 (oui Unknown), length 300

For information : fa:16:3e:34:bf:36 is the MAC Adresse of the VM Nic hosted by ESSEX-2.

So, If I resume :

  • The OVS bridge is working
  • DNSMASQ is working (in local that sure, but not with br-int)
  • VMs hosted by ESSEX-1 have network
  • VMs hosted by ESSEX-2 don't have network

Any idea guys ?

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answered 2012-06-08 12:21:43 -0500

emilienm gravatar image

I close this question, and here is the following stuffs : (

Thank's to everybody :-)

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answered 2012-06-05 16:18:46 -0500

askstack gravatar image

Emilien Sorry I did not get back to you sooner, I was on vacation for a week. Have you tried using a ethernet directly connecting the two eth1 ports. This way it will by pass the switch and no packets will get dropped.

my network setting.

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answered 2012-05-28 10:21:05 -0500

emilienm gravatar image

To all, here the situation today.

-> Node 1 : nova.conf : ( -> Node 2 : nova.conf : (

Here my nova-compute.conf for both servers :

--libvirt_type=kvm --libvirt_use_virtio_for_bridges=true --libvirt_ovs_bridge=br-int --libvirt_vif_type=ethernet --libvirt_vif_driver=nova.virt.libvirt.vif.LibvirtOpenVswitchDriver

On both servers : ovs-vsctl add-port br-int eth1

My /var/lib/nova/networks/nova-gw-bcc5fbd4-a1.conf is NOT empty : fa:16:3e:3b:c6:3b,host-, fa:16:3e:59:ed:5a,host-,

But, no VM gets an IP from DHCP (neither VMs hosted by ESSEX-1 nor ESSEX-2).

When i do a tcpdump -i br-int | grep DHCP on both servers, I can see a lot of requests : 10:13:00.942132 IP > BOOTP/DHCP, Request from 00:25:90:4b:25:21 (oui Unknown), length 300 10:13:01.230608 IP > BOOTP/DHCP, Request from 00:25:90:4b:24:ab (oui Unknown), length 300

But it seems DNSMASQ does not answer with a network configuration.

What do you think :

  • an issue with DNSMASQ ?
  • a problem with the bridge ?

If someone has a multinode architecture with Quantum + OVS which is working, please provide any information about what he did.

Thank you

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answered 2012-05-24 17:00:23 -0500

askstack gravatar image

Emilien I have a second node working now. I don't have nova-compute.conf. Both hosts are using nova.conf.

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answered 2012-05-24 15:25:49 -0500

emilienm gravatar image

Hi Askstack,

Can you share with me your configurations files (nova.conf, nova-compute.conf, OVS commands you did)


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answered 2012-05-24 15:12:03 -0500

askstack gravatar image

Emilien This is only a single node setup with quantum+ovs. I will be working on a second node though.

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answered 2012-05-23 22:04:10 -0500

emilienm gravatar image

@astack :

Can you give more details ?

In multi-node compute architecture ? With OVS ?

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answered 2012-05-23 18:53:41 -0500

askstack gravatar image

I droped the nova db and created a new one, did a "nova-manage db sync". After that I was able to launch VMs with dhcp IP addresses. Thanks Hyunsun Moon and dan wendlandt

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answered 2012-05-22 23:32:57 -0500

askstack gravatar image

Hyunsun Moon Thanks for your help. I do want to use the VLAN mode. I just didn't find a good tutorial for it.

By looking at the /var/log/message, it appears nova+quantum are doing the same thing as the cookbook. May 22 18:47:39 core01 ovs-vsctl: 00001|vsctl|INFO|Called as /usr/bin/ovs-vsctl -- --may-exist add-port br-int tapb8dc6e11-26 -- set Interface tapb8dc6e11-26 external-ids:iface-id=b8dc6e11-2640-4950-b383-1df2645dd73c -- set Interface tapb8dc6e11-26 external-ids:iface-status=active -- set Interface tapb8dc6e11-26 external-ids:attached-mac=fa:16:3e:14:26:c7 -- set Interface tapb8dc6e11-26 external-ids:vm-uuid=b0e42af1-8376-4d36-979d-aafbfc47fb57 May 22 18:47:40 core01 ovs-vsctl: 00001|vsctl|INFO|Called as /usr/bin/ovs-vsctl --timeout=2 set Port tapb8dc6e11-26 tag=10

Probably I am stll doing something wrong with the trunk port or I need to "Networks created using other Nova network managers are not compatible with Quantum. When using Quantum with nova, you must start with a fresh Nova database to make sure that no previous networks created using other network managers exist. ", according the admin guide.

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Asked: 2012-05-18 14:45:39 -0500

Seen: 428 times

Last updated: Jun 08 '12