Cisco Cisco Packet Data Gateway (PDG) Nota Di Rilascio
SGSN Changes in Release 15.0
▀ SGSN Enhancements for November 30, 2013
▄ Cisco ASR 5x00 Release Change Reference
498
CSCuh99198 - CLI config to Accept RAB negotiation for PDP Activation in S4-
SGSN
Feature Changes
Configurable Control of RAB Negotiation in S4-SGSN
Previous Behavior: Per TS 23.060 section 9.2.2.1A, the S4-SGSN rejects PDP activation if RNC negotiates QoS
during RAB assignment.
during RAB assignment.
However, in some networks, the RNCs do negotiate QoS due to :
1. RNC is pre-R9 and the network knows that the UE is not capable beyond certain bit rates. So it negotiates the
MBR / GBR values to what is acceptable to the UE.
2. RNC has resource constraints or it is a legacy RNC capable of only certain bit rates, hence the network gives
only what is possible for the RNC to accept.
Scenario 1 is the most common case in a Gn SGSN + pre-R9 RNC deployment. But case (1) means the UE is not EPC-
capable so the SGSN will not allow use of the S4 interface for such UEs -- unless the UE has an EPS subscription.
capable so the SGSN will not allow use of the S4 interface for such UEs -- unless the UE has an EPS subscription.
Scenario 2, the S4-SGSN rejects PDP activation.
New Behavior: To allow customers to support legacy RNCs, the SGSN now supports a new CLI to configure S4-SGSn
acceptance of PDP activation even with such legacy RNCs. The CLI changes are documented below and use requires
the S4-SGSN license.
acceptance of PDP activation even with such legacy RNCs. The CLI changes are documented below and use requires
the S4-SGSN license.
Customer Impact: Provides flexibility to control S4-SGSN behavior based on CLI configuration if RNC negotiates
QoS. A CLI modification is needed for activation case alone as the default behavior, per 3GPP spec, is to reject
activation, which is service impacting. Hence, to avoid such service impacts a configuration is added to control the
behavior.
QoS. A CLI modification is needed for activation case alone as the default behavior, per 3GPP spec, is to reject
activation, which is service impacting. Hence, to avoid such service impacts a configuration is added to control the
behavior.
Command Changes
qos-modification
If the S4 interface is used for PDP activation and the new keyword
allow-s4-rab-negotiation
is configured , then
the SGSN locally accepts what the RNC sends as QoS in the RAB Assignment Response and sends that QoS in the
Activate Accept.
Activate Accept.
configure
context context_name
sgsn-service sgsn_service_name
qos-modification { inform-rnc-before-ue | allow-s4-rab-negotiation }
[ no ] qos-modification [ inform-rnc-before-ue | allow-s4-rab-negotiation ]
end
Notes:
The SGW and/or PGW will not be informed of the modified QoS, which is a per bearer MBR / GBR rate.