The GGSN activates
or modifies a bearer whenever a service flow matches a statically
provisioned Policy and Charging Control (PCC) rule. The network,
based on QoS requirements of the application/service, determines
what bearers are needed and either modifies an existing bearer or
activates a new one.
Statically provisioned
PCC rules, called Network Requested Operation (NRO) rules, are configured
as charging rules in the Active Charging Service (ACS). As a part
of charging action for such rules, QoS-needed and corresponding
Traffic Flow Template (TFT) packet filters are configured. QoS-needed
mainly consists of QoS Class Identifier (QCI) and data rates. Whereas, TFT
mainly consists of uplink and downlink packet filter information.
 Warning |
This feature does not work in conjunction
with IMS-Authorization service.
|
When a packet arrives,
the ACS analyzes it and performs rule matching based on the priority in
the rulebase. If an NRO rule bound to the context on which the packet
arrived matches, ACS applies the bandwidth limit and gating. If
an NRO rule bound to some other context matches, ACS discards the
packet.
If an unbound NRO
rule matches, ACS finds a context with the same QCI as the NRO rule, where
the context's Maximum Bit Rate (MBR) and matched rule's
MBR (context's MBR + matched rule's MBR) is less than the
MBR for that QCI in the APN. If such a context is found, NRUPC for
that context is triggered. If the request succeeds, the rule will
be bound to that context.
Important: The packet that triggered
the NRUPC request is discarded.
If no context satisfying
the MBR limit is found, or if there is no context with the same
QCI as the NRO rule, the system triggers NRSPCA. If the request
succeeds, the rule is bound to that context.
Important: The packet that triggered
the NRSPCA request is discarded.
TFTs from the charging-action
associated with the NRO rule are also sent as part of the NRUPC/NRSPCA
request, and returned as part of the Create PDP Context Response.
Finally, if a non-NRO
rule matches, ACS proceeds with the normal processing of that packet.
Non-NRO charging-actions can still do "flow action" or
ITC (limit-for-flow-type and limit-for-bandwidth).
ACS also does the
following:Before making an NRUPC/NRSPCA
Request, ACS checks if there is any outstanding request for the
same QCI for the same subscriber. If there is, it will not process
the new request and discards the packet.
After a context is
terminated, ACS unbinds all the rules bound to that context. Such
a rule can later be bound to some other context when a packet matches
that rule.
Important: The packet that triggered
the NRUPC/NRSPCA request is discarded.