I am using VM to install Openstack ICEHOUSE Single Node setup, using a single NIC etho, by following [(https://fosskb.wordpress.com/2014/04/12/openstack-icehouse-on-ubuntu-12-04-lts-single-machine-setup/)] first of all my understanding about the Openstack Packet flow for a single node is:

VMs --> br-int --> br-eth1 [for vlans] -->br-ex [for external connectivity], is it right?

Then I have Edited file: /etc/network/interfaces

auto lo iface lo inet loopback

auto eth0
iface eth0 inet manual
                up  ip address add 0/0 dev $IFACE
                up ip link set $IFACE up
                up ifconfig $IFACE promisc
                up ifconfig $IFACE multicast
                down  ip link set $IFACE down

auto br-ex
iface br-ex inet static
                address  10.3.1.145
                netmask  255.255.255.0
                network  10.3.1.0
                broadcast  10.3.1.255
                gateway  10.3.1.254
                up ifconfig $IFACE promisc
                dns-nameservers  10.3.1.102

Defined networks [Flat and VLAN] in /etc/neutron/plugins/ml2/ml2_conf.ini, so
[ml2]
type_drivers=flat,vlan
tenant_network_types=vlan,flat
 [ml2_type_flat]
flat_networks=External
[ml2_type_vlan]
network_vlan_ranges=Intnet1:100:200
.....
[ovs]
bridge_mappings=External:br-ex,Intnet1:br-eth1
 =========================================
Created bridges and ports:
ovs-vsctl add-br br-int
ovs-vsctl add-br br-eth1
ovs-vsctl add-br br-ex
ovs-vsctl add-port br-eth1 eth1
ovs-vsctl add-port br-ex eth0

Created Router, with 2 networks [Internal 10.3.11.0/24 and External 10.3.1.0/24 (with only 4 IPs in a row)]
Now I can ping
10.3.11.0   --> 10.3.11.254
10.3.11.0   --> 10.3.1.216 [router's external interface]
10.3.11.0   --> 10.3.1.217-8 [Other Instance and Floating IP], and 10.3.1.145 its server IP
But NO LUCK TO HIT 10.3.1.254

any suggestion or solution will be highly appreciable.

Regards Ali Murtaza Solangi