This extension introduces these concepts:
- VIP
The primary load balancing configuration object. Specifies the virtual IP address and port where client traffic is received. Also defines other details such as the load balancing method to be used, protocol, and so on.
This entity is sometimes known in load-balancing products as a virtual server, vserver, or listener.
- pool
A logical set of devices, such as web servers, that you group together to receive and process traffic.
The load balancing function chooses which member of the pool handles the new requests or connections received on the VIP address. Each VIP has one pool.
- pool member
The application that runs on the back-end server.
- health monitor
Determines whether or not back-end members of the VIP pool can process a request. A pool can have several health monitors associated with it.
The LBaaS extension supports these types of health monitors:
PING. Pings the members by using ICMP.
TCP. Connects to the members by using TCP.
HTTP. Sends an HTTP request to the member.
HTTPS. Sends a secure HTTP request to the member.
When a pool has several monitors associated with it, all monitors check each member of the pool. If any monitor declares a member as unhealthy, the member status is changed to inactive and the member does not participate in the load balancing for the pool.
All monitors must declare the member to be healthy for it to stay active.
- session persistence
Forces connections or requests in the same session to be processed by the same member as long as it is active.
The LBaaS extension supports these types of persistence:
SOURCE_IP. All connections that originate from the same source IP address are handled by the same member of the pool.
HTTP_COOKIE. The load balancing function creates a cookie on the first request from a client. Subsequent requests that contain the same cookie value are handled by the same member of the pool.
APP_COOKIE. The load balancing function relies on a cookie established by the back-end application. All requests with the same cookie value are handled by the same member of the pool.
Absence of
session_persistenceattribute means no session persistence mechanism is used.When no session persistence is used, the
session_persistenceattribute does not appear in the API response, instead of returning null.You can clear session persistence for the VIP by sending
nullinsession_persistenceattribute in a VIP update request.
