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What is external inetrface of network node?

asked 2015-01-20 07:19:14 -0600

Yedhu Sastri gravatar image

Iam very new to openstack. I succesffully tried Openstack-Devstack instalation on single node. Now i started minimal architecture with neutron netwokring with compute node, controller node and netwrok node. I dont understand what is 3rd NIC of Network Node doing. What is the purpose of interface without any IP?? My OS is ubuntu 14.04 LTS. My 3rd NIC of Network Node is eth3. I edited /etc/network/interfaces as given in the Openstack documentation. After reeboot eht3 is updated without any IP. is that needed?? Any tests needed to perfom to check whether I have done correct configuartion for eth3?? please help...

my /etc/network/interfaces is

auto lo
iface lo inet loopback

allow-hotplug eth1
auto eth1
iface eth1 inet static
        address 192.168.9.10
        netmask 255.255.255.0
        gateway 192.168.9.254
        dns-nameservers 8.8.8.8

allow-hotplug eth2
auto eth2
iface eth2 inet static
        address 10.0.1.21
        netmask 255.255.255.0


auto eth3
allow-hotplug eth3
iface eth3 inet manual
        up ip link set dev $IFACE up
        down ip link set dev $IFACE down
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answered 2015-01-20 10:17:49 -0600

dbaxps gravatar image

View page 20 at https://www.hastexo.com/system/files/...

1.The packet leaves the VM and hits the hypervisor node on br-int
2.From there,it is forwarded to br-tun,which adds the GRE encapsulation to it
3.It leaves the hypervisor on eth2 into the GRE network
4.It reaches eth2 on the network node
5.It gets sent through br-tun,which removes the GRE Headers
6.It is then forwarded to br-int(br-int on the network node is connected to the
qROUTERnamespace--that is why we defined our external network as router for
the admin tenant network earlier)
7.From br-int,the packet hits the external bridge(br-ex) and finally leaves the
network node into the internet

You can replace "GRE" by "VXLAN" in text above and it will have the same sense.
Eth3 is OVS port of external OVS bridge br-ex ( having IP belongs to external network ). That's why it doesn't have IP. It's IP got moved to external OVS bridge br-ex ( Network Node).
On RH systems corresponding ifcfg-* files look like :-

[root@juno1 network-scripts(keystone_admin)]# cat ifcfg-br-ex
DEVICE="br-ex"
BOOTPROTO="static"
IPADDR="192.168.1.127"
NETMASK="255.255.255.0"
DNS1="83.221.202.254"
BROADCAST="192.168.1.255"
GATEWAY="192.168.1.1"
NM_CONTROLLED="no"
DEFROUTE="yes"
IPV4_FAILURE_FATAL="yes"
IPV6INIT=no
ONBOOT="yes"
TYPE="OVSIntPort"
OVS_BRIDGE=br-ex
DEVICETYPE="ovs"

[root@juno1 network-scripts(keystone_admin)]# cat ifcfg-enp2s0
DEVICE="enp2s0"
# HWADDR=00:22:15:63:E4:E2
ONBOOT="yes"
TYPE="OVSPort"
DEVICETYPE="ovs"
OVS_BRIDGE=br-ex
NM_CONTROLLED=no
IPV6INIT=no

and ovs-vsctl show report on Network Node looks as follows

. . . . . . . . . . . . . . . . . . . . 
 Bridge br-ex
        Port br-ex
            Interface br-ex
                type: internal
        Port "enp2s0"
            Interface "enp2s0"
        Port phy-br-ex
            Interface phy-br-ex
                type: patch
                options: {peer=int-br-ex}
        Port "qg-a632b464-07"
            Interface "qg-a632b464-07"
                type: internal
    ovs_version: "2.3.1"
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Asked: 2015-01-20 07:19:14 -0600

Seen: 218 times

Last updated: Jan 20 '15