The Pool Assign agent can dynamically assign a local traffic pool; it provides this configuration element only: selection of a static pool.
In a per-session policy, the Pool Assign agent enables session-based pool selection from among valid pools in this priority order: a pool selected by an iRule that is defined for the virtual server takes precedence over any other; a static pool defined in the Pool Assign agent takes precedence over a static pool defined for the virtual server.
In a per-request policy, the Pool Assign agent enables request-based pool selection for reverse proxy (LTM+APM) only. In a per-request policy, the Pool Assign agent specifies the pool to use.
In a per-request policy, using the Pool Assign agent in a forward proxy configuration does not work and is not supported.