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Manual Chapter: Configuring Device-Specific Probing and Statistics Collection
Manual Chapter
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Overview: Configuring device-specific probing and statistics collection

BIG-IP Global Traffic Manager (GTM) performs intelligent probing of your network resources to determine whether the resources are up or down. In some circumstances, for example, if your network contains firewalls, you might want to set up device-specific probing to specify which BIG-IP systems probe specific servers for health and performance data.

About Prober pools

A Prober pool is an ordered collection of one or more BIG-IP systems. A BIG-IP system can be a member of more than one Prober pool, and a Prober pool can be assigned to an individual server or a data center. When you assign a Prober pool to a data center, by default, the servers in that data center inherit that Prober pool.

The members of a Prober pool perform monitor probes of servers to gather data about the health and performance of the resources on the servers. BIG-IP GTM makes load balancing decisions based on the gathered data. If all of the members of a Prober pool are marked down, or if a server has no Prober pool assigned, BIG-IP GTM reverts to a default intelligent probing algorithm to gather data about the resources on the server.

The following figure illustrates how Prober pools work. BIG-IP GTM contains two BIG-IP Local Traffic Manager (LTM) systems that are assigned Prober pools and one BIG-IP LTM system that is not assigned a Prober pool:

Example illustration of how Prober pools work Example illustration of how Prober pools work
Prober Pool 1 is assigned to a generic host server
BIG-IP LTM3 is the only member of Prober Pool 1, and performs all HTTPS monitor probes of the server.
Prober Pool 2 is assigned to generic load balancers
BIG-IP LTM1 and BIG-IP LTM2 are members of Prober Pool 2. These two systems perform HTTP monitor probes of generic load balancers based on the load balancing method assigned to Prober Pool 2.
The generic load balancers on the left side of the graphic are not assigned a Prober pool
BIG-IP GTM can solicit any BIG-IP system to perform FTP monitor probes of these load balancers, including systems that are Prober pool members.

About Prober pool status

The status of a Prober pool also indicates the status of the members of the pool. If at least one member of a Prober pool has green status (Available), the Prober pool has green status.

The status of a Prober pool member indicates whether the BIG-IP GTM system, on which you are viewing status, can establish an iQuery connection with the member.

Note: If a Prober pool member has red status (Offline), no iQuery connection exists between the member and the BIG-IP GTM system on which you are viewing status. Therefore, that BIG-IP GTM system cannot request that member to perform probes, and the Prober pool will not select the member for load balancing.

About Prober pool statistics

You can view the number of successful and failed probe requests that the BIG-IP GTM system (on which you are viewing statistics) made to the Prober pools. These statistics reflect only the number of Probe requests and their success or failure. These statistics do not reflect the actual probes that the pool members made to servers on your network.

Prober pool statistics are not aggregated among the BIG-IP GTM systems in a synchronization group. The statistics on one BIG-IP GTM include only the requests made from that BIG-IP GTM system.

In the following figure, the Prober pool statistics that display on BIG-IP GTM1 are the probe requests made only by that system.

Prober pool statistics displayed per system Prober pool statistics displayed per system

Task summary

Perform these tasks to configure device-specific probing and statistics collection.

Creating a Prober pool

Obtain a list of the BIG-IP systems in your network and ensure that a server object is configured for each system on BIG-IP GTM.
Create a Prober pool that contains the BIG-IP systems that you want to perform monitor probes of a specific server or the servers in a data center.
  1. On the Main tab, click Global Traffic > Prober Pools. The Prober Pool List screen opens.
  2. Click Create. The New Prober Pool screen opens.
  3. In the Name field, type a name for the Prober pool.
    Important: Prober pool names are limited to 63 characters.
  4. Select a method from the Load Balancing Method list.
    Option Description
    Round Robin BIG-IP GTM load balances monitor probes among the members of a Prober pool in a circular and sequential pattern.
    Global Availability BIG-IP GTM selects the first available Prober pool member to perform a monitor probe.
  5. Assign members to the pool by moving servers from the Available list to the Selected list.
  6. To reorder the members in the Selected list, choose a server and use the Up and Down buttons to move the server to a different location in the list. The order of the servers in the list is important in relation to the load balancing method you selected.
  7. Click Finished.
Assign the Prober pool to a data center or a server.

Assigning a Prober pool to a data center

Ensure that a Prober pool is available on the system.
To make a specific collection of BIG-IP systems available to probe the servers in a data center, assign a Prober pool to the data center.
  1. On the Main tab, click Global Traffic > Data Centers. The Data Center List screen opens.
  2. Click a data center name in the list. The data center settings and values display.
  3. From the Prober Pool list, select the Prober pool that contains the BIG-IP systems that you want to perform monitor probes of the servers in this data center. By default, all of the servers in the data center inherit this Prober pool.
  4. Click Finished.

Assigning a Prober pool to a server

Ensure that a Prober pool is available on the system.
To specify which BIG-IP systems perform monitor probes of a server, assign a Prober pool to the server.
  1. On the Main tab, click Global Traffic > Servers. The Server List screen opens.
  2. Click a server name. The server settings and values display.
  3. From the Prober Pool list, select one of the following.
    Option Description
    Inherit from Data Center By default, a server inherits the Prober pool assigned to the data center in which the server resides.
    Prober pool name Select the Prober pool that contains the BIG-IP systems that you want to perform monitor probes of this server.
  4. Click Finished.

Viewing Prober pool statistics and status

You can view status and statistics for Prober pools and the members of the pools.
  1. On the Main tab, click Global Traffic > Prober Pools. The Prober Pool List screen opens.
  2. On the menu bar, click Statistics. The Global Traffic Statistics screen opens.
  3. Click the Refresh button. The statistics are updated.
  4. To view additional information about the status of a Prober pool, place your cursor over the icon in the Status column.
  5. To view additional information about the status of a Prober pool member, click View in the Members column, and then place your cursor over the icon in the Status column of a specific member.

Determining which Prober pool member marked a resource down

When a resource is marked down, you can open the BIG-IP GTM log to view the SNMP trap and determine which member of a Prober pool marked the resource down.
  1. On the Main tab, click System > Logs. The System Logs screen opens.
  2. On the menu bar, click Global Traffic. The Global Traffic Logs screen opens.
  3. You can either scroll through the log or search for a log entry about a specific event.

Implementation result

You now have an implementation in which a specific BIG-IP system probes the resources on a specific server, or the servers in a specific data center.

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