Manual Chapter :
Configuring the BIG-IP System to Auto-Populate Pools
Applies To:
Show VersionsBIG-IP AAM
- 15.1.10, 15.1.9, 15.1.8, 15.1.7, 15.1.6, 15.1.5, 15.1.4, 15.1.3, 15.1.2, 15.1.1, 15.1.0, 15.0.1, 15.0.0
BIG-IP APM
- 16.1.5, 16.1.4, 16.1.3, 16.1.2, 16.1.1, 16.1.0, 16.0.1, 16.0.0, 15.1.10, 15.1.9, 15.1.8, 15.1.7, 15.1.6, 15.1.5, 15.1.4, 15.1.3, 15.1.2, 15.1.1, 15.1.0, 15.0.1, 15.0.0
BIG-IP Analytics
- 16.1.5, 16.1.4, 16.1.3, 16.1.2, 16.1.1, 16.1.0, 16.0.1, 16.0.0, 15.1.10, 15.1.9, 15.1.8, 15.1.7, 15.1.6, 15.1.5, 15.1.4, 15.1.3, 15.1.2, 15.1.1, 15.1.0, 15.0.1, 15.0.0
BIG-IP Link Controller
- 16.1.5, 16.1.4, 16.1.3, 16.1.2, 16.1.1, 16.1.0, 16.0.1, 16.0.0, 15.1.10, 15.1.9, 15.1.8, 15.1.7, 15.1.6, 15.1.5, 15.1.4, 15.1.3, 15.1.2, 15.1.1, 15.1.0, 15.0.1, 15.0.0
BIG-IP LTM
- 16.1.5, 16.1.4, 16.1.3, 16.1.2, 16.1.1, 16.1.0, 16.0.1, 16.0.0, 15.1.10, 15.1.9, 15.1.8, 15.1.7, 15.1.6, 15.1.5, 15.1.4, 15.1.3, 15.1.2, 15.1.1, 15.1.0, 15.0.1, 15.0.0
BIG-IP PEM
- 16.1.5, 16.1.4, 16.1.3, 16.1.2, 16.1.1, 16.1.0, 16.0.1, 16.0.0, 15.1.10, 15.1.9, 15.1.8, 15.1.7, 15.1.6, 15.1.5, 15.1.4, 15.1.3, 15.1.2, 15.1.1, 15.1.0, 15.0.1, 15.0.0
BIG-IP AFM
- 16.1.5, 16.1.4, 16.1.3, 16.1.2, 16.1.1, 16.1.0, 16.0.1, 16.0.0, 15.1.10, 15.1.9, 15.1.8, 15.1.7, 15.1.6, 15.1.5, 15.1.4, 15.1.3, 15.1.2, 15.1.1, 15.1.0, 15.0.1, 15.0.0
BIG-IP DNS
- 16.1.5, 16.1.4, 16.1.3, 16.1.2, 16.1.1, 16.1.0, 16.0.1, 16.0.0, 15.1.10, 15.1.9, 15.1.8, 15.1.7, 15.1.6, 15.1.5, 15.1.4, 15.1.3, 15.1.2, 15.1.1, 15.1.0, 15.0.1, 15.0.0
BIG-IP ASM
- 16.1.5, 16.1.4, 16.1.3, 16.1.2, 16.1.1, 16.1.0, 16.0.1, 16.0.0, 15.1.10, 15.1.9, 15.1.8, 15.1.7, 15.1.6, 15.1.5, 15.1.4, 15.1.3, 15.1.2, 15.1.1, 15.1.0, 15.0.1, 15.0.0
Configuring the BIG-IP System to Auto-Populate Pools
Overview: Using host names to identify pool members and nodes
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.
You can configure a BIG-IP system with nodes and pool members that are identified with
fully-qualified domain names (FQDNs). When you configure pool members with FQDN, addresses will
dynamically follow DNS changes. Fully dynamic DNS-managed pools may even be created. In the
following illustration, the BIG-IP Local Traffic Manager creates an
ephemeral pool member for each IP address returned in the DNS response.
This next illustration shows another option. With this configuration, the
system sends a DNS query for the FQDN, and then creates only one ephemeral node or pool
member using the first IP address returned in the DNS response. An advantage to this
configuration is that you can change the IP addresses of the backend servers that host the
domain without reconfiguring the BIG-IP system. If your DNS servers are configured to round
robin the DNS responses, be sure that the DNS servers return all available.
About modes of failure and related nodes or pool members
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.
Task summary
for configuring BIG-IP auto-populate pools
Perform these tasks to configure the system to auto-populate
pools.
Creating a default gateway pool
Create a default gateway pool for the system to use to forward
traffic.
- On the Main tab, click.The Pool List screen opens.
- ClickCreate.The New Pool screen opens.
- In theNamefield, type a unique name for the pool.
- For theHealth Monitorssetting, from theAvailablelist, select thegateway_icmpmonitor and move the monitor to theActivelist.
- Using theNew Memberssetting, add each router that you want to include in the default gateway pool:
- Type the IP address of a router in theAddressfield.
- Type an asterisk (*) in theService Portfield, or select*All Servicesfrom the list.
- ClickAdd.
- ClickFinished.
Configuring the
BIG-IP system to handle DNS lookups
Configure how the BIG-IP system handles DNS lookups when you want to use
fully-qualified domain names (FQDNs) to identify nodes and pool members.
- On the Main tab, click.The DNS Device configuration screen opens.
- In the DNS Lookup Server List area, in theAddressfield, type the IP address of the DNS server(s) you want to add.The system uses these DNS servers to validate DNS lookups and resolve host names. Then, clickAdd.If you did not disable DHCP before the first boot of the system, and if the DHCP server provides the information about your local DNS servers, then this field is automatically populated.
- ClickUpdate.
Creating nodes using host names
Determine the fully-qualified domain name (FQDN) that you want to use to identify a
node.
You can create nodes identified by FQDNs and then create a pool and add pool
members from a list of nodes.
- On the Main tab, expandLocal Traffic, and clickNodes.The Node List screen opens.
- Click theCreatebutton.The New Node screen opens.
- In theNamefield, type a descriptive label for the node.Names are case-sensitive.
- For theAddresssetting, selectFQDN, and then type the host name in the field.
- In the Configuration area, from theHealth Monitorslist, select the way that you want the system to apply monitors to the node.The default setting isNode Default.Node DefaultSpecifies 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 SpecificSpecifies that the system monitors this node with the monitors that you configure in theSelect Monitorssetting.When you select theNode Specificoption, the screen refreshes to display theSelect Monitorssetting.NoneSpecifies that the system does not monitor this node.
- In theRatiofield, type a number for the ratio weight of the node.
- In theConnection Limitfield, type a number for the maximum established connection limit for the node.
- In theConnection Rate Limitfield, type a number that specifies the number of new connections accepted per second for the node.
- From theAddress Typelist, select whether the node resolves to an IPv4 or IPv6 address. The default isIPv4.
- From theAuto Populatelist, selectEnabled. The options are:EnabledThe 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.DisabledThe system automatically creates a node that corresponds to the IP address of only the first DNS entry of the resolved FQDN.
- In theIntervalfield, type the number of seconds before the system creates new ephemeral nodes or deletes expired ephemeral nodes based on the IP addresses returned in response to a DNS query for the FQDN of the node. The default is the TTL of the IP address in the DNS response.
- In theDown Intervalfield, type the number of seconds the system waits to mark an FQDN node down following a DNS query failure.
- ClickFinished.The screen refreshes, and the new node appears in the node list.
Creating a pool using host names
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 return all available IP addresses,
instead of just one IP address.
When you want the BIG-IP system to automatically update pool
members as you make changes to the IP addresses of servers in your network, you can
create a pool of servers that are identified by FQDNs.
- On the Main tab, click.The Pool List screen opens.
- ClickCreate.The New Pool screen opens.
- In theNamefield, type a unique name for the pool.
- For theHealth Monitorssetting, from theAvailablelist, select a monitor and move the monitor to theActivelist.A pool containing nodes represented by FQDNs cannot be monitored byinbandorsaspmonitors.
- From theLoad Balancing Methodlist, select how the system distributes traffic to members of this pool.The default isRound Robin.
- In theNew Memberssetting, add at least one node with a static IP address. This node serves as a fallback if a DNS query returns no records for the nodes identified by FQDNs.
- SelectNode List.
- From theAddresslist, select a node identified by a static IP address.
- From theService Portlist, make a selection.
- ClickAdd.
- In theNew Memberssetting, add the members that you want to include in the pool using FQDNs.
- SelectFQDN Node List.
- From theAddresslist, select a node identified by an FQDN.
- Make a selection from theService Portlist.
- In theNew Memberssetting, selectEnabled. The options are:EnabledThe 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.DisabledThe system selects the first address and generates an ephemeral for that address.
- ClickAdd.
- Repeat steps 7-9 to add additional members to the pool.
- ClickFinished.The screen refreshes, and you see the new pool in the Pool list.
About modifying nodes and pool members identified by host names
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.
Task summary
Disabling a node
Determine the node that you want to disable.
You can disable a node when you want to make changes to your network, but you want
persistent and active connections to be completed before the BIG-IP system marks the node as down.
- On the Main tab, click.The Node List screen opens.
- In the Name column, click a node name.
- In the State area, clickDisabled (Only persistent or active connections allowed).You can only disable the parent FQDN node or pool member. After disabling, the ephemeral dependents are then disabled, but you cannot directly disable an ephemeral node.
- ClickUpdate.The screen refreshes, and the status in the Availability area changes.
Disabling a pool member
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.
Disable a pool member when you want to make changes to your network, but you want
persistent and active connections to be completed before the BIG-IP system marks the pool member as down.
- On the Main tab, click.The Pool List screen opens.
- Click a pool name in the Pool List.
- On the menu bar, clickMembers.
- In theMemberlist, select the relevant pool member.
- In the State area, clickDisabled (Only persistent or active connections allowed).
- ClickUpdate.The screen refreshes, and the status in the Availability area changes.
About pool member and node statistics
You can view statistics about pool members and nodes identified by host names.
Task summary
Viewing statistics for a specific node
Ensure that at least one LTM node exists on the BIG-IP system.
You can view statistics for an LTM node when you want to analyze BIG-IP system
traffic.
- On the Main tab, click.The Local Traffic statistics screen opens.
- From theStatistics Typelist, selectNodes.Information displays about the node.
Viewing statistics for ephemeral pool members
Ensure that at least one LTM node exists on the BIG-IP system.
When you want to analyze how the BIG-IP system is handling traffic, you can view
statistics for pools and pool members, including the ephemeral pools created when the
pool member is identified by a fully-qualified domain name (FQDN) and
Auto
Populate
is enabled for the pool member. - On the Main tab, click.The Local Traffic statistics screen opens.
- From theStatistics Typelist, selectPools.Information displays about the pools configured on the BIG-IP system. The ephemeral pool members are shown indented below their parent pool member and with two dashes preceding the pool member name.