Fundamentals of load balancing
There are three major components to a load balancer in Neutron:
Pool members
Pools
Virtual IPs
A pool member is a layer 4 object that is composed of the IP address and listening port of a service. For example, a pool member might be a web server with a configured IP address of 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:
10.30.0.2:80Server B:
10.30.0.4:80Server 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 often mapped to a domain name.
Note
The term virtual IP is also used in reference to VRRP, a router redundancy protocol, and should not be confused with its use in the context of load balancing...
