Comment 4 for bug 1586584

Adding a neutron API like this is very useful.
First, tenants can see the virtual network topology clearly and it contributes to understanding and planning network. Also ,it can reduce the requirement of the basic knowledge.
Second, for administrators , they can know how many devices connected to the network, and the details about every device, such as tenant_id, node, ip etc. So we can limit the number of instances in a network, also can know it whether supports dhcp ,floating-ip or not.
Third, it can simplify a lot of work for neutron developers. Don't need using nova command, such as "nova list", "nova interface-list" etc, we can know all information about network . If there are a ip which is unreachable, using neutron new API can search the network,instance, node, port about the ip directly. Just spend a little time on assuring the host node when we need to check the configuration environment or capture packets.