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In this case, the routing for 203.0.113.0/24 is done by an external router ( yours or your providers ) via gw 203.0.113.1

So the 203.0.113.1 is not inside your OS environment. When you configure the provider net, you tell neutron about the subnet and the gw address ( some more parameters are possible, like vlan id ..) . When you setup a router inside your OS env, you need add a gateway, which will be located inside the provider net. This router then will receive a public IP frpm nside this net ( e.g. 203.0.113.2 ). If everything is correct, you will then be able to ping that ip. The router's IP exists inside a so call namespace. You can inspect the namespaces with the command ip netns. You may see something like qrouter-a2da1577-b986-4af9-bbd6-9718f6294920 With "ip netns exec qrouter-a2da1577-b986-4af9-bbd6-9718f6294920 ip a" you will then be able see the routers Gateway IP. Physically the interface only needs to be set as manually up. that's why:

  1. iface INTERFACE_NAME inet manual
    ip link set dev $IFACE up

In this case, the routing for 203.0.113.0/24 is done by an external router ( yours or your providers ) via gw 203.0.113.1

So the 203.0.113.1 is not inside your OS environment. When you configure the provider net, you tell neutron about the subnet and the gw address ( some more parameters are possible, like vlan id ..) . When you setup a router inside your OS env, you need to add a gateway, which will be located inside the provider net. This router then will receive a public IP frpm nside from inside this net ( e.g. 203.0.113.2 ). If everything is correct, you will then be able to ping that ip. The router's IP exists inside a so call namespace. You can inspect the namespaces with the command ip netns. You may see something like

qrouter-a2da1577-b986-4af9-bbd6-9718f6294920
With "ip netns exec qrouter-a2da1577-b986-4af9-bbd6-9718f6294920 ip a" you will then be able see the routers Gateway IP.

Physically the interface only needs to be set as manually up. that's why:

  1. iface INTERFACE_NAME inet manual
    ip link set dev $IFACE up

In this case, the routing for 203.0.113.0/24 is done by an external router ( yours or your providers ) via gw 203.0.113.1

So the 203.0.113.1 is not inside your OS environment. When you configure the provider net, you tell neutron about the subnet and the gw address ( some more parameters are possible, like vlan id ..) . When you setup a router inside your OS env, you need to add a gateway, which will be located inside the provider net. This router then will receive a public IP from inside this net ( e.g. 203.0.113.2 ). If everything is correct, you will be able to ping that ip. The router's IP exists inside a so call called namespace. You can inspect the namespaces with the command ip netns. You may see something like

qrouter-a2da1577-b986-4af9-bbd6-9718f6294920 With "ip " ip netns exec qrouter-a2da1577-b986-4af9-bbd6-9718f6294920 ip a" a you will then be able see the routers Gateway IP.

IP.

Physically the interface only needs to be set as manually up. that's why:

iface INTERFACE_NAME inet manual
ip link set dev $IFACE up