A traffic group is a collection of related configuration objects that run on a BIG-IP® device. Together, these objects process a particular type of traffic on that device. When a BIG-IP device becomes unavailable, a traffic group floats (that is, fails over) to another device in a device group to ensure that application traffic continues to be processed with little to no interruption in service. In general, a traffic group ensures that when a device becomes unavailable, all of the failover objects in the traffic group fail over to any one of the devices in the device group, based on the number of active traffic groups on each device.
A traffic group is initially active on the device on which you create it, until the traffic group fails over to another device. For example, if you initially create three traffic groups on Device A, these traffic groups remain active on Device A until one or more traffic groups fail over to another device. If you want to balance the traffic group load among all devices in the device group, you can intentionally cause a traffic group to fail over to another device. You do this using the Force to Standby option of the Configuration utility.
Only certain types of configuration objects can belong to a traffic group. Examples of traffic group objects are self IP addresses and virtual IP addresses.
An example of a set of objects in a traffic group is an iApps™ application service. If a device with this traffic group is a member of a device group, and the device becomes unavailable, the traffic group floats to another member of the device group, and that member becomes the device that processes the application traffic.
When a traffic group fails over to another device in the device group, the device that the system selects is normally the device with the least number of active traffic groups. When you initially create the traffic group on a device, however, you specify the device in the group that you prefer that traffic group to run on in the event that the available devices have an equal number of active traffic groups (that is, no device has fewer active traffic groups than another). Note that, in general, the system considers the most available device in a device group to be the device that contains the fewest active traffic groups at any given time.
When you initially run the Setup utility on a device or upgrade from a previous BIG-IP® version, the system creates two default traffic groups:
A MAC masquerade address is a unique, floating Media Access Control (MAC) address that you create and control. You can assign one MAC masquerade address to each traffic group on a BIG-IP device. By assigning a MAC masquerade address to a traffic group, you indirectly associate that address with any floating IP addresses (services) associated with that traffic group. With a MAC masquerade address per traffic group, a single VLAN can potentially carry traffic and services for multiple traffic groups, with each service having its own MAC masquerade address.
A primary purpose of a MAC masquerade address is to minimize ARP communications or dropped packets as a result of a failover event. A MAC masquerade address ensures that any traffic destined for the relevant traffic group reaches an available device after failover has occurred, because the MAC masquerade address floats to the available device along with the traffic group. Without a MAC masquerade address, on failover the sending host must relearn the MAC address for the newly-active device, either by sending an ARP request for the IP address for the traffic or by relying on the gratuitous ARP from the newly-active device to refresh its stale ARP entry.
The assignment of a MAC masquerade address to a traffic group is optional. Also, there is no requirement for a MAC masquerade address to reside in the same MAC address space as that of the BIG-IP device.
The following configuration restrictions apply to traffic groups:
Perform this task when you want to create a traffic group for a BIG-IP® device. You can perform this task on any BIG-IP device within the device group, and the task creates a traffic group on that device. To cause the traffic group to run on another device in the device group, use the Force to Standby button. Forcing a traffic group into a standby state on the local device causes the traffic group to become active on a remote device.
During any config sync operation, each traffic group within a device group is synchronized to the other device group members. Therefore, on each device, a particular traffic group is in either an active state or a standby state. In an active state, a traffic group on a device processes application traffic. In a standby state, a traffic group on a device is idle.
When a device with an active traffic group becomes unavailable, the active traffic group floats to another device, choosing whichever device in the device group is most available at that moment. The term floats means that on the target device, the traffic group switches from a standby state to an active state.
This task causes the selected traffic group on the local device to switch to a standby state. By forcing the traffic group into a standby state, the traffic group becomes active on another device in the device group. For device groups with more than two members, you can choose the specific device to which the traffic group fails over. This task is optional.
The types of configuration objects that you can associate with a floating traffic group are:
You can associate configuration objects with a traffic group in these ways:
Within a Sync-Failover type of device group, each BIG-IP® device has a specific designation with respect to a traffic group. That is, a device in the device group can be a default device, as well as a current device or a next active device.
|Default Device||A default device is a device that you specify on which a traffic group
runs after failover. A traffic group fails over to the default device in these cases:
|Current Device||A current device is the device on which a traffic group is currently running. For example, if Device A is currently processing traffic using the objects in Traffic-Group-1, then Device A is the current device. If Device A becomes unavailable and Traffic-Group-1 fails over to Device C (currently the device with the fewest number of active traffic groups), then Device C becomes the current device. The current device is system-selected, and might or might not be the default device.|
|Next Active Device||A next active device is the device currently designated to accept a traffic group if failover of a traffic group should occur. For example, if traffic-group-1 is running on Device A, and the designated device for future failover is currently Device C, then Device C is the next active device. The next active device can be either system- or user-selected, and might or might not be the default device.|
The failover feature includes an option known as auto-failback. When you enable auto-failback, a traffic group that has failed over to another device fails back to its default device whenever that default device is available to process the traffic. This occurs even when other devices in the group are more available than the default device to process the traffic.
If auto-failback is not enabled for a traffic group and the traffic group fails over to another device, the traffic group runs on the failover (now current) device until that device becomes unavailable. In that event, the traffic group fails over to the most available device in the group. The traffic group only fails over to its default device when the availability of the default device equals or exceeds the availability of another device in the group.
This table lists and describes the properties of a traffic group.
|Name||The name of the traffic group, such as Traffic-Group-1.|
|Partition / Path||The name of the folder or sub-folder in which the traffic group resides.|
|Description||A user-defined description of the traffic group.|
|Default Device||The device with which a traffic group has some affinity when auto-failback is not enabled.|
|Current Device||The device on which a traffic group is currently running.|
|Next Active Device||The device currently most available to accept a traffic group if failover of that traffic group should occur.|
|MAC Masquerade Address||A user-created MAC address that floats on failover, to minimize ARP communications and dropped connections.|
|Auto Failback||The condition where the traffic group tries to fail back to the default device whenever possible.|
|Auto Failback Timeout||The number of seconds before auto failback expires. This setting appear only when you enable the Auto Failback setting.|
|Floating||A designation that makes if possible for the traffic group to float to another device in the device group when failover occurs.|