The PCRF Sub-Pool Selection table contains rules for selection of a PCRF Sub-Pool for a given PCRF Pool and Origin-Host value.
It is sometimes necessary to subdivide a PCRF Pool into sub-pools; for example, to support controlled routing of traffic to a new PCRF. In such a case, you can configure PCRF Sub-Pool Selection Rules to a selected a sub-pool on the basis of the Origin-Host of the binding capable session initiation request.
A PCRF Sub-Pool Selection Rule has the following attributes:
- The Default PCRF Pool can have sub-pools.
- The PCRF Pool Name column contains hyperlinks to the PCRF Pools page filtered by the PCRF Pool Name.
- Origin-Host is the only supported PCRF Sub-Pool Selection parameter.
- Supported Origin-Host operators are: Equals, Starts With, and Ends With.
- Priority values can range from 1 to 99, with 1 being the highest priority.
An APN-to-PCRF Pool mapping specifies that all binding-capable session initiation requests that result in creation of a new binding should be routed to a PCRF in PCRF Pool 'X'.
A PCRF Sub-Pool Selection Rule can override the APN-to-PCRF Pool mapping by specifying binding-capable session initiation requests that result in new bindings that were destined for PCRF Pool 'X', but come from PCEF 'Y', should be routed to a PCRF in PCRF Sub-Pool 'Z'.
A PCRF Sub-Pool Selection Rule will never be considered if no APN is mapped to its PCRF Pool. As a result, it is safe to add PCRF Sub-Pool Selection Rules prior to mapping APNs to the PCRF Pool that is being subdivided. It is also acceptable to add PCRF Sub-Pool Selection Rules for a PCRF Pool that is already mapped to an APN. However, if this is done, bindings that were created prior to the existence of the PCRF Sub-Pool Selection Rule take precedence over the PCRF Sub-Pool chosen for new binding-capable session initiation requests that arrive after the new rule is in place. This behavior is necessary to prevent split bindings.
PCRF Sub-Pool Selection Rules are configured using the NOAMP GUI as a network-wide managed object.
The creation of a new PCRF Sub-Pool Selection Rule does not affect P-DRA signaling in any way until both of the following conditions exist:
- An APN is mapped to the PCRF Pool using the Access Point Names GUI
- A binding-capable session initiation request arrives with an APN mapped to that PCRF Pool and an Origin-Host that matches the Condition specified in the PCRF Sub-Pool Selection Rule.
When a PCRF Sub-Pool Selection Rule entry is added, new bindings from that APN and Origin-Host will be routed to a PCRF in the specified PCRF Sub-Pool. When a PCRF Sub-Pool Selection Rule is mapped to a PCRF Sub-Pool, a check is performed to determine if the selected PCRF Sub-Pool is configured with a PRT mapping at each site. If at least one site does not have a mapping for the selected PCRF Sub-Pool, a confirmation dialog is displayed that including a warning as follows:
- If a site does not have the PCRF Sub-Pool mapped to a PRT table, a confirmation dialog is displayed on the APN GUI warning that Site 'X' does not have a mapping defined for this PCRF Sub-Pool. You can choose to continue, but with the knowledge that a call might fail at that site if a binding-capable session initiation request arrives with an APN and Origin-Host that is mapped to that PCRF Sub-Pool.
- If a site cannot be reached due to network errors, a confirmation dialog is displayed on to warn you that it cannot be determined whether Site 'X' has a mapping defined for this PCRF Sub-Pool. You can choose to continue, but with the knowledge that a call might fail at that site if a binding-capable session initiation request arrives with an APN and Origin-Host that is mapped to that PCRF Pool.
The PCRF Sub-Pool Selection Rule GUI prevents creation of rules that are:
- Ambiguous
- Conflicting
- Duplicate
Two rules are considered as
ambiguous if the following criteria are met:
- The rules have the same PCRF Pool values and
- The rules have the same Priority values and
- The rules have different PCRF Sub-Pool values and one of the following is true:
- One rule has an Origin-Host with a "Starts With" operator and the other rule has an Origin-Host with an "Ends With" operator -- OR –
- For example, starts With ab and Ends With xyz
- Value length is not considered as a factor in the best match decision at this time.
- Both rules have an Origin-Host with a "Starts With" operator and all of the value characters of the shorter value match the first characters of the longer value -- OR –
- For example, starts With abc and Starts With ab
- Both rules have an Origin-Host with a "Ends With" operator and all of the value characters of the shorter value match the last characters of the longer value.
- For examples, ends With xyz and Ends With yz
Two rules are considered to be
conflicting if all of the following criteria are met:
- The rules have the same PCRF Pool values.
- The rules have the same Priority values.
- The rules have the same Origin-Host operators and values.
- The rules have different PCRF Sub-Pool values.
Two rules are considered to be
duplicate if all of the following criteria are met:
- The rules have the same PCRF Pool values.
- The rules have the same Origin-Host operators and values.
- The rules have the same PCRF Sub-Pool values.