PCRF Selection and Routing
PCRF selection involves distribution of subscriber bindings to PCRFs that are configured in advance. When a Diameter Request message arrives on a Gx, Gxx, or S9 interface aiming at generating a new session, the Policy DRA must determine if a binding already exists for the IMSI APN included in the Diameter message.
If a binding-capable session initiation request is received that would result in a new binding, and no PCRFs are configured at the site, Policy DRA generates an error response.
Note:
This does not apply if a binding already exists for the IMSI and APN, or IMSI and PCRF Pool.See Query Subscriber's Binding Status for a description of PCRF selection when PCRF Pooling is enabled.