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 (such as a need 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 certain attributes:
- The Default PCRF Pool can have sub-pools.
- The
PCRF Pool Name column contains
hyperlinks to the PCRF Pools screen 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 a pair of conditions exist:
- An APN is mapped to the PCRF Pool using the Access
Point Names screen.
- 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:
- 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 certain 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 several conditions 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
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
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.
