Cisco Cisco ASR 5000
Serving GPRS Support Node (SGSN) Overview
▀ Features and Functionality
▄ SGSN Administration Guide, StarOS Release 18
The SGSN's Ge support includes use of the gprsSSF CAMEL component with the SGSN and the gsmSCF component
with the SCP.
with the SCP.
CAMEL Configuration
To provide the CAMEL interface on the SGSN, a new service configuration mode, called “CAMEL Service”, has been
introduced on the SGSN.
introduced on the SGSN.
1. An SCCP Network configuration must be created or exist already.
2. A CAMEL Service instance must be created.
3. The CAMEL Service instance must be associated with either the SGSN Service configuration or the GPRS
2. A CAMEL Service instance must be created.
3. The CAMEL Service instance must be associated with either the SGSN Service configuration or the GPRS
Service configuration in order to enable use of the CAMEL interface.
4. The CAMEL Service must be associated with the SCCP Network configuration.
Until a CAMEL Service is properly configured, the SGSN will not process any TDP for pdp-context or mo-sms.
Commandguard
Operators can accidentally enter configuration mode via CLI or file replay. To protect against this, SGSN supports
commandguard
CLI command. Commandguard, which is disabled by default, can only be enabled or disabled from the
Global Configuration mode. When Commandguard is enabled it affects the
configure
and
autoconfirm
CLI
commands by causing them to prompt (Y/N) for confirmation. When
autoconfirm
is enabled Commandguard has no
affect. The commandguard state is preserved in the SCT and, when enabled, is output by the various variants of the
show config
CLI.
Configurable RAB Asymmetry Indicator in RAB Assignment Request
The SGSN sets the value for the RAB Asymmetry Indicator that is included in the RAB Assignment Request.
In releases prior to R12.0, the SGSN set the RAB asymmetry indicator to "Symmetric-Bidirectional" when downlink
and uplink bit rates were equal. Now, the SGSN selects the value based on the symmetry of negotiated maximum bit
rates as follows:
and uplink bit rates were equal. Now, the SGSN selects the value based on the symmetry of negotiated maximum bit
rates as follows:
If the uplink and downlink bit rates are equal then it is set to “Symmetric-Bidirectional”,
If uplink bit rate is set to 0 kbps, then it is set to “Asymmetric-Unidirectional-Downlink”,
If downlink bit rate is set to 0 kbps, then it is set to “Asymmetric-Unidirectional-Uplink”,
If the uplink and downlink bit rates are non-zero and different, then it is set to “Asymmetric-Bidirectional”.
A change in CLI configuration allows the SGSN to override the above functionality and set the RAB Asymmetry
Indicator to “Asymmetric-Bidirectional” when uplink and downlink bit rates are equal. As a result, two sets of bit rates -
one for downlink and one for uplink - will be included in the RAB Assignment Requests as mandated in 3GPP TS
25.413.
Indicator to “Asymmetric-Bidirectional” when uplink and downlink bit rates are equal. As a result, two sets of bit rates -
one for downlink and one for uplink - will be included in the RAB Assignment Requests as mandated in 3GPP TS
25.413.
Congestion Control
With Release 17, the SGSN supports several of the 3GPP TS23.060 R10 machine type communications (MTC)
overload control mechanisms to be used in the handling of signaling bursts from machine-to-machine (M2M) devices:
overload control mechanisms to be used in the handling of signaling bursts from machine-to-machine (M2M) devices:
General congestion control – applicable only for Mobility Management messages.