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br-ex configuration on ubuntu

asked 2015-05-30 18:05:05 -0500

adendukuri gravatar image

updated 2015-05-30 23:02:29 -0500

dbaxps gravatar image

In this document, it appears that it is necessary to configure br-ex in the /etc/network/interfaces file.

This is how we configured /etc/network/interfaces file on network node in 3 node configuration.

on network node

auto br-ex
 iface br-ex inet static

but I am not able to ping which is the gateway. Something is not right.

as br-ex interface connected to external network which in this case eth2 which is connected to router having internet access the gateway for this connection

Can somebody guide in this.

Thanks Arun

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Please provide output of the following commands/files.

ovs-vsctl show
ip route
netstat -nr
cat /etc/network/interfaces
Tobias Urdin gravatar imageTobias Urdin ( 2015-05-30 19:31:39 -0500 )edit

2 answers

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answered 2015-05-30 23:18:14 -0500

dbaxps gravatar image

updated 2015-05-31 00:46:45 -0500

Take a look at this schema :- image description

    Br-ex is supposed to be OVS BRIDGE with IP belongs, third Ehernet interface eth2 ( Network Node, not   supporting  mgmt network  and VXLAN (GRE, VLAN data) tunnel is supposed to be OVS PORT of br-ex.

Eth2 should be connected to external router . Br-ex is supposed to belong external network the same on which outside router resides

To configure the Open vSwitch (OVS) service

# service openvswitch-switch restart
Add the external bridge:
# ovs-vsctl add-br br-ex
Add a port to the external bridge that connects to the physical external network interface:
Replace INTERFACE_NAME with the actual interface name. For example, eth2 or ens256.
# ovs-vsctl add-port br-ex INTERFACE_NAME

regarding Eth2 configuration in /etc/network/interfaces
Same manual advises :

External on with gateway

Then your physical outside router should have IP, otherwise , at least via my experience,
it won't work.

 Your gateway and external network created via Neutron CLI or via Dashboard should match real ones. I mean IP addresses been used for gateway and external network address and network mask.

otherwise, physical router won't work for you.

auto br-ex
 iface br-ex inet static
 address 192.168.1.(XX)

# The external network interface
auto eth2
iface eth2  inet manual
        up ip link set dev $IFACE up
        down ip link set dev $IFACE down
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BTW , Your question
is addressed as well.

dbaxps gravatar imagedbaxps ( 2015-05-31 00:50:55 -0500 )edit

answered 2015-05-31 10:50:57 -0500

jiangjun gravatar image

Agree with @dbaxps

Actually, what we need to do is just MOVE eth2's original ip TO br-ex.

Before all the operation, we assume that eth2 has YOUR_ETH2_IP. After moving IP to br-ex, we still need to enable eth2 (but has no IP), add eth2 into br-ex, and correct the route table.

You can manually test by the following steps: (not permanent, lost after reboot)

ifconfig br-ex promisc up
ifconfig eth2
ifconfig eth2 promisc 
ifconfig br-ex YOUR_ETH2_IP netmask YOUR_NETMASK

ovs-vsctl add-port br-ex eth2

# Then, re-add the default route if needed
ip route add default via YOUR_GATEWAY_IP

@dbaxps 's answer has the right steps for a permanent network configuration for br-ex & eth2.

Finally, you can follow his configuration.

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What do you mean "YOUR_ETH2_IP" here? 192.168.1.XX is a tenant subnet IP, right? why it is not (router gateway)?

Allen Liu gravatar imageAllen Liu ( 2015-10-22 15:33:37 -0500 )edit

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Asked: 2015-05-30 18:05:05 -0500

Seen: 22,628 times

Last updated: May 31 '15