This is the hack to create a routed (not NAT-ed) virtual network in Openstack with Openvswitch that was installed using PackStack.

  • create a new virtual network as usual
    • let say vnet1 with subnet=subnet1
    • do not mark this new vnet as external
  • create a new neutron router
    • let say r1
    • use existing external network as the gateway interface
    • take a note on what is the external network IP assigned to this router
      • let say the IP=gw_ip_1
    • attach the new vnet to this neutron router
      • in this example, attach vnet1 to this neutron router

  • disable snat on this neutron router

      neutron router-gateway-set --disable-snat <routername> <external network name>
    
  example:
  neutron router-gateway-set --disable-snat r2 public

  • Add routes to the new virtual network via the newly created neutron router external IP

      example: 
  # ip r add subnet1 via gw_ip_1

  • Outside openstack, make sure you have route towards your new subnet (subnet1) point to the network node IP address

  • openstack with ovs - disable snat on neutron router

  • packstack - add non-nat virtual network
    • create new vnet as usual, let say vnet1 with subnet=subnet1
    • do not mark this new vnet as external
    • create a new neutron router, let say r1
      • use existing external network as the gateway interface
      • take a note on what is the external network IP assigned to this router, let say the IP=gw_ip_1
      • attach the new vnet to this neutron router
    • disable snat on this neutron router
      • see “openstack with ovs - disable snat on neutron router” section above
    • go to network node
      • add static route to the new vnet subnet via the external
        • example: ip r add subnet1 via gw_ip_1
    • Outside openstack, make sure you have route towards your new subnet (subnet1) point to the network node IP address