Cisco Cisco ASR 5000
Serving GPRS Support Node (SGSN) Overview
Features and Functionality ▀
SGSN Administration Guide, StarOS Release 18 ▄
The new Gb Manager provides increased flexibility in handling link level procedures for each access type independently
and ensures scalability. The consequence of relieving the Link Manager, of a large amount of message handling, is to
decrease delays in sending sscop STAT messages resulting in the detection of link failure at the remote end. Use of this
separate new proclet to handle 2G signaling messages means there will not be any MTP link fluctuation towards the
RNS, which is seen during the BSC restart or extension activity in the network. As well, this improves the fluctuation
towards the 3G connectivity.
and ensures scalability. The consequence of relieving the Link Manager, of a large amount of message handling, is to
decrease delays in sending sscop STAT messages resulting in the detection of link failure at the remote end. Use of this
separate new proclet to handle 2G signaling messages means there will not be any MTP link fluctuation towards the
RNS, which is seen during the BSC restart or extension activity in the network. As well, this improves the fluctuation
towards the 3G connectivity.
GMM-SM Event Logging
To facilitate troubleshooting, the SGSN will capture procedure-level information per 2G or 3G subscriber (IMSI-based)
in CSV formatted event data records (EDRs) that are stored on an external server.
in CSV formatted event data records (EDRs) that are stored on an external server.
This feature logs the following events:
Attaches
Activation of PDP Context
RAU
ISRAU
Deactivation of PDP Context
Detaches
Authentications
PDP Modifications
The new SGSN event logging feature is enabled/disabled per service via CLI commands. For more information on this
feature, refer to the section GMM/SM Event Logging in this guide.
feature, refer to the section GMM/SM Event Logging in this guide.
Gn/Gp Delay Monitoring
The SGSN measures the control plane packet delay for GTP-C signaling messages on the SGSN’s Gn/Gp interface
towards the GGSN.
towards the GGSN.
If the delay crosses a configurable threshold, an alarm will be generated to prompt the operator.
A delay trap is generated when the GGSN response to an ECHO message request is delayed more than a configured
amount of time and for a configured number of consecutive responses. When this occurs, the GGSN will be flagged as
experiencing delay.
amount of time and for a configured number of consecutive responses. When this occurs, the GGSN will be flagged as
experiencing delay.
A clear delay trap is generated when successive ECHO Response (number of successive responses to detect a delay
clearance is configurable), are received from a GGSN previously flagged as experiencing delay.
clearance is configurable), are received from a GGSN previously flagged as experiencing delay.
This functionality can assist with network maintenance, troubleshooting, and early fault discovery.
GTP-C Path Failure Detection and Management
The SGSN now provides the ability to manage GTP-C path failures detected as a result of spurious restart counter
change messages received from the GGSN.
change messages received from the GGSN.
Previous Behavior: The old default behavior was to have the Session Manager (SessMgr) detect GTP-C path failure
based upon receiving restart counter changes in messages (Create PDP Context Response or Update PDP Context
based upon receiving restart counter changes in messages (Create PDP Context Response or Update PDP Context