The BIG-IP® acceleration functionality caches objects from origin web servers and delivers them directly to clients. The BIG-IP device handles both static content and dynamic content, by processing HTTP responses, including objects referenced in the response, and then sending the included objects as a single object to the browser. This form of caching reduces server TCP and application processing, improves web page loading time, and reduces the need to regularly expand the number of web servers required to service an application.
Configuring BIG-IP acceleration in a server-farm configuration involves creation of a Sync-Only device group for two or more devices in a pool, creation of a parent folder for acceleration objects under /Common on each device, and synchronization of all devices in the Sync-Only device group.
BIG-IP® acceleration in a server farm deployment comprises multiple devices in a scalable trusted deployment, operating as peers in a pool behind a load balancer. Each BIG-IP device within the pool separately processes traffic and maintains a discrete cache. Because a BIG-IP server farm deployment requires a trusted deployment, the configuration, invalidations, and performance statistics are shared across the BIG-IP devices within the device group.
A BIG-IP server farm deployment
One of the types of device groups that you can create is a Sync-Only device group. A Sync-Only device group contains devices that synchronize configuration data with one another, but their configuration data does not fail over to other members of the device group. A maximum of 32 devices is supported in a Sync-Only device group.
A device in a trust domain can be a member of more than one Sync-Only device group. A device can also be a member of both a Sync-Failover group and a Sync-Only group.
A typical use of a Sync-Only device group is one in which you configure a device to synchronize the contents of a specific folder to a different device group than to the device group to which the other folders are synchronized.
Before any BIG-IP® devices on a local network can synchronize configuration data or fail over to one another, they must establish a trust relationship known as device trust. Device trust between any two BIG-IP devices on the network is based on mutual authentication through the signing and exchange of x509 certificates.
Devices on a local network that trust one another constitute a trust domain. A trust domain is a collection of BIG-IP devices that trust one another and can therefore synchronize and possibly fail over their BIG-IP configuration data, as well as exchange status and failover messages on a regular basis. A local trust domain is a trust domain that includes the local device, that is, the device you are currently logged in to. You can synchronize a device's configuration data with either all of the devices in the local trust domain, or to a subset of devices in the local trust domain.
The trust domain is represented by a system-generated device group named device_trust_group, which the system uses internally to synchronize trust domain information across all devices. You cannot delete this special device group from the system.
You can use a Sync-Only device group to synchronize policy data in a specific folder across a local trust domain.
Sync-Only Device Group
The devices in a BIG-IP® device group use x509 certificates for mutual authentication. Each device in a device group has an x509 certificate installed on it that the device uses to authenticate itself to the other devices in the group.
Device identity is a set of information that uniquely identifies that device in the device group, for the purpose of authentication. Device identity consists of the x509 certificate, plus this information:
Perform these tasks to create a Sync-Only device group.
Perform these tasks to accelerate HTTP traffic in a server farm.
The BIG-IP devices are configured to accelerate HTTP traffic in a server farm.