You create nodes on the BIG-IP® system to represent the backend servers on your network. In turn, you create pool members to represent the backend servers on your network when you create a pool and want to load balance traffic to multiple backend servers.
BIG-IP system auto-populating a pool and routing traffic to the pool members
BIG-IP system routing traffic to a node identified by a host name
If a node or pool member that is identified by a fully-qualified domain name (FQDN) is down for a specified amount of time, the BIG-IP® system marks the node or pool member down. Failure to resolve a FQDN will not cause the marking down of nodes or pool members currently in service. While the status of the FQDN node or pool member for DNS is reflected in the status of the FQDN node, since the FQDN node or pool member does not itself monitor any servers, its status does not contribute to the status of the pool in any way.
Failure of a monitored ephemeral to respond to monitor probes results in the marking down of a specific node. Niether the FQDN or any of the related ephemeals are directly affected. Because ephemeral objects monitor servers, the status of the epemeral node or pool member affects the pool status in the same way as any other pool member or node.
Perform these tasks to configure the BIG-IP® system to auto-populate pools.
|Node Default||Specifies that the system uses the defined default monitors for nodes. The default monitors are defined on the Default Monitors screen of the BIG-IP Configuration utility.|
|Node Specific||Specifies that the system monitors this node with the monitors that
you configure in the Select Monitors setting.
Note: When you select the Node Specific option, the screen refreshes to display the Select Monitors setting.
|None||Specifies that the system does not monitor this node.|
|Enabled||The system automatically creates ephemeral nodes using the IP addresses returned by the resolution of a DNS query for the FQDN, that is, for each DNS entry of the resolved FQDN.|
|Disabled||The system automatically creates a node that corresponds to the IP address of only the first DNS entry of the resolved FQDN.|
Before creating a pool, determine the servers that you want to add to the pool using a fully-qualified domain name (FQDN).
Ensure that your DNS servers are not configured for round robin DNS resolutions; instead, ensure that your DNS servers return all available IP addresses in a DNS resolution.
|Enabled||The system generates an ephemeral node for each IP address returned in response to a DNS query for the FQDN of the node. Additionally, when a DNS response indicates the IP address of an ephemeral node no longer exists, the system deletes the ephemeral node.|
|Disabled||The system selects the first address and generates an ephemeral for that address.|
When you change the configuration of a fully-qualified domain name (FQDN) pool member or node, any ephemeral pool members or nodes that the BIG-IP® system created based on the IP addresses returned in a DNS response for that FQDN are automatically modified, as well. For example, if you change the monitor on an FQDN node, the system automatically changes the monitor assigned to the ephemeral nodes associated with that node.
When you want to modify an FQDN pool member or node, but you want persistent and active connections to be completed before the BIG-IP system marks the pool member or node as down, disable the pool member or node first, and then make modifications.
Determine the node that you want to disable.
Determine the pool member that you want to disable. You can only disable a parent fully-qualified domain name (FQDN) node or pool member. The ephemeral dependents are then disabled. You cannot directly disable the ephemerals.
You can view statistics about pool members and nodes identified by host names.