Cisco Cisco ASR 5000
Subscriber Overcharging Protection
▀ Feature Overview
▄ SGSN Administration Guide, StarOS Release 18
Feature Overview
Subscriber Overcharging Protection enables the SGSN to avoid overcharging the subscriber if/when a loss of radio
coverage (LORC) occurs.
coverage (LORC) occurs.
When a mobile is streaming or downloading files from external sources (for example, via a background or interactive
traffic class) and the mobile goes out of radio coverage, the GGSN is unaware of such loss of connectivity and continues
to forward the downlink packets to the SGSN.
traffic class) and the mobile goes out of radio coverage, the GGSN is unaware of such loss of connectivity and continues
to forward the downlink packets to the SGSN.
Previously, upon loss of radio coverage (LORC), the SGSN did not perform the UPC procedure to set QoS to 0kbps, as
it does when the traffic class is either streaming or conversational. Therefore, when the SGSN did a Paging Request, if
the mobile did not respond the SGSN would simply drop the packets without notifying the GGSN; the G-CDR would
have increased counts but the S-CDR would not, causing overcharges when operators charged the subscribers based on
the G-CDR.
it does when the traffic class is either streaming or conversational. Therefore, when the SGSN did a Paging Request, if
the mobile did not respond the SGSN would simply drop the packets without notifying the GGSN; the G-CDR would
have increased counts but the S-CDR would not, causing overcharges when operators charged the subscribers based on
the G-CDR.
Now operators can accommodate this situation, they can configure the SGSN to set QoS to 0kbps, or to a negotiated
value, upon detecting the loss of radio coverage. The overcharging protection feature relies upon the SGSN adding a
proprietary private extension to GTP LORC Intimation IE to messages. This LORC Intimation IE is included in UPCQ,
DPCQ, DPCR, and SGSN Context Response GTP messages. One of the functions of these messages is to notify the
GGSN to prevent overcharging.
value, upon detecting the loss of radio coverage. The overcharging protection feature relies upon the SGSN adding a
proprietary private extension to GTP LORC Intimation IE to messages. This LORC Intimation IE is included in UPCQ,
DPCQ, DPCR, and SGSN Context Response GTP messages. One of the functions of these messages is to notify the
GGSN to prevent overcharging.
The GGSN becomes aware of the LORC status by recognizing the message from the SGSN and discards the downlink
packets if LORC status indicates loss of radio coverage or stops discarding downlink packets if LORC status indicates
gain of radio coverage for the UE.
packets if LORC status indicates loss of radio coverage or stops discarding downlink packets if LORC status indicates
gain of radio coverage for the UE.
The following table summarizes the SGSN's actions when radio coverage is lost or regained and LORC overcharging
protection is enabled.
protection is enabled.
Table 48. LORC Conditions and Overcharging Protection
Condition
Triggered by
SGSN Action
LORC Intimation IE - private
extension payload
extension payload
Loss of radio coverage
(LORC)
(LORC)
RNC sends Iu release request with
cause code matching configured
value
cause code matching configured
value
Send UPCQ to GGSN
Start counting unsent
packets/bytes
Stop forwarding packets in
downlink direction
Start counting unsent
packets/bytes
Stop forwarding packets in
downlink direction
No payload
Mobile regains coverage
in same SGSN area
in same SGSN area
MS/SGSN
Send UPCQ to GGSN
Stop counting unsent
packets/bytes
Stop discarding downlink
packets
Stop counting unsent
packets/bytes
Stop discarding downlink
packets
New loss-of-radio-coverage
state and unsent packet/byte
counts
state and unsent packet/byte
counts
Mobile regains coverage
in different SGSN area
in different SGSN area
MS/SGSN
Send SGSN Context
Response message to new
SGSN
Stop counting unsent
packets/bytes
Response message to new
SGSN
Stop counting unsent
packets/bytes
Unsent packet/byte counts
PDP deactivated during
LORC
LORC
MS/SGSN
Send DPCQ to GGSN
Stop counting unsent
packets/bytes
Stop counting unsent
packets/bytes
Unsent packet/byte counts