← Back to team overview

openstack team mailing list archive

Re: [Quantum & OVS] How to bi-direction communicate between VM instances and "old" LAN network(s)


Hi Chu,

I was able to get my instances and  LAN servers communicate by following the below steps. The basic idea is that you should add the external network interface to br-ex,  then create an external network in quantum with --router:external=True and allocate floating IPs to your instances from this external network. Now your LAN servers can talk to your instances using these routable floating IPs that you have allocated from the external network.


1.      Create an external bridge named br-ex and add the network card to that bridge. Also assign an IP on the external bridge so you can manage it. Assuming eth1 is your network card.

sudo ovs-vsctl add-br br-ex

sudo ovs-vsctl add-port br-ex eth1

sudo ip addr add <ip/mask> dev br-ex

sudo ip link set br-ex up

2.      Set eth1 as a promiscuous interface in Ubuntu with no IP address so your host OS does not mess with it.

Edit your /etc/network/interfaces and add the below lines:

iface eth1 inet manual

    up ifconfig $IFACE up

    up ifconfig $IFACE promisc

    down ifconfig $IFACE down

3.      Create a shared public network and subnet for your tenant routers to plug in.

Note that this network should be mapped to your existing LAN network and you should also set an existing gateway and assign IP allocation pools.

quantum net-create public --shared --router:external=True --provider:network_type local

quantum subnet-create --name public-subnet --gateway <gateway-ip>  --allocation-pool start=<start-ip>,end=<end-ip> public <external-LAN-subnet/mask>

4.      Then set an external gateway IP for your tenant routers and create your user nets

quantum router-create router1

quantum router-gateway-set router1 public

quantum net-create usernet1

quantum subnet-create --name subnet1 usernet1

quantum router-interface-add router1 subnet1

5.      To enable bi-directional network communication your old LAN network server farm use floating IPs. Allocate a floating IP and map it to your instance port either using command line or via horizon.

quantum floatingip-create --port_id $SERVER_PORT_ID public

Hope this helps.


From: Openstack [mailto:openstack-bounces+najoy=cisco.com@xxxxxxxxxxxxxxxxxxx] On Behalf Of Chu Duc Minh
Sent: Wednesday, May 22, 2013 5:04 AM
To: openstack@xxxxxxxxxxxxxxxxxxx
Subject: [Openstack] [Quantum & OVS] How to bi-direction communicate between VM instances and "old" LAN network(s)

Hi, i deployed a Openstack Grizzly cluster with Quantum using network-model "Per-tenant Routers with Private Networks". Everything is ok.
Now, i need to communicate (bi-direction) between VM network(s) and "old" LAN network(s) of old server farm. (<>,<>, v.v...)
I added a network card to Network-node and plug it to a LAN network (<>).
But still not yet figured out how i can achieve it (old server farm can connect to VM instance and vice-versa)
Could you help me, pls? Thanks a lot, folks!
PS: I attach my network topology in this mail for reference.
I think that, maybe I need to create a new "br-ex" for LAN, create port/interface in router of each tenant, then add a LAN IP (192.168.3.x) to router-interface.
Then add route to<> to

But "how to implement it" still not clear... :-(

Follow ups