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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
 address 203.0.113.101
 netmask 255.255.255.0
 gateway 203.0.113.1
 dns-nameservers 8.8.8.8

but I am not able to ping 203.0.113.1 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 192.168.1.1

Can somebody guide in this.

Thanks Arun

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Please provide output of the following commands/files.

ifconfig
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 192.168.1.0/24, 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

Follow http://docs.openstack.org/kilo/instal...
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

View http://docs.openstack.org/kilo/instal...
regarding Eth2 configuration in /etc/network/interfaces
Same manual advises :

External on 203.0.113.0/24 with gateway 203.0.113.1

Then your physical outside router should have IP 203.0.113.1, 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 192.168.1.1 won't work for you.

auto br-ex
 iface br-ex inet static
 address 192.168.1.(XX)
 netmask 255.255.255.0
 gateway 192.168.1.1
 dns-nameservers 8.8.8.8

# 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 https://ask.openstack.org/en/question...
is addressed as well.

dbaxps gravatar imagedbaxps ( 2015-05-31 00:50:55 -0500 )edit
0

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 0.0.0.0
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 203.0.113.101 (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: 17,733 times

Last updated: May 31 '15