There are three major components to a load balancer in Neutron:
Pool member(s)
Pool(s)
Virtual IP(s)
A pool member is a layer 4 object and is composed of the IP address of a service and the listening port of the service. For example, a pool member might be a web server with a configured IP address, 10.30.0.2, listening on TCP port 80.
A pool is a group of pool members that typically serve identical content. A pool composed of web servers, for example, may resemble the following membership:
Server A: 10.30.0.2:80
Server B: 10.30.0.4:80
Server C: 10.30.0.6:80
A virtual IP, or VIP, is an IP address that resides on the load balancer and listens for incoming connections. The load balancer then balances client connections among the members of the associated pool. A virtual IP is usually exposed to the Internet and is often mapped to a domain name.