Cisco Cisco ASR 5000
Monitoring and Troubleshooting
▀ Troubleshooting
▄ SGSN Administration Guide, StarOS Release 18
Troubleshooting
Troubleshooting is tricky unless you are very familiar with the system and the configuration of the system and the
various network components. The issue is divided into three groups intended to assist you with diagnosing problems and
determining courses of action.
various network components. The issue is divided into three groups intended to assist you with diagnosing problems and
determining courses of action.
Problems and Issues
Table 55. Possible Problems
Problem
Analysis
Users cannot Attach to the SGSN -
Attach Failure
Attach Failure
Typically, the root cause is either a fundamental configuration error or a connection
problem either on the system (the SGSN) or the network.
Configuration changes may have been made incorrectly on either the SGSN or on the
signalling network or access network equipment.
problem either on the system (the SGSN) or the network.
Configuration changes may have been made incorrectly on either the SGSN or on the
signalling network or access network equipment.
Users can Attach to the SGSN but
cannot Activate a PDP Context.
cannot Activate a PDP Context.
In most cases, this type of problem is related either to an issue with the LAN
connectivity between the SGSN and the DNS server or a general connectivity problem
between the SGSN and a GGSN.
connectivity between the SGSN and the DNS server or a general connectivity problem
between the SGSN and a GGSN.
Users can Attach to the SGSN, they can
Activate a PDP Context but data transfer
isn’t happening.
Activate a PDP Context but data transfer
isn’t happening.
The problem could be between the GGSN and an external server. The PDP Context
indicates that the tunnel between the SGSN and the GGSN is intact, but the lack of
data transfer suggests that external servers can not be reached.
indicates that the tunnel between the SGSN and the GGSN is intact, but the lack of
data transfer suggests that external servers can not be reached.
Users can Attach to the SGSN, they can
Activate a PDP Context but they
encounter other problems.
Activate a PDP Context but they
encounter other problems.
Problems, such as slow data transfer or a session disconnect for an already established
session, can be caused by congestion during high traffic periods, external network
problems, or handover problems.
session, can be caused by congestion during high traffic periods, external network
problems, or handover problems.
Troubleshooting More Serious Problems
You will see that the commands from the Daily Health Check section are also used for troubleshooting to diagnose
problems and possibly discover solutions. And of course, your Support Team is always available to help.
problems and possibly discover solutions. And of course, your Support Team is always available to help.
Causes for Attach Reject
If an SGSN receives Attach Request messages but responds with Attach Rejects, then the reason might be found in one
of the cause codes. These codes are included as attributes in the Reject messages and can be seen during monitoring
with the following command:
of the cause codes. These codes are included as attributes in the Reject messages and can be seen during monitoring
with the following command:
monitor subscriber IMSI
Single Attach and Single Activate Failures
To troubleshoot an Attach or Activate problem for a single subscriber, you will need to begin with the subscriber’s MS-
ISDN number. The attached flow chart suggests commands that should assist with determining the root of the problem:
ISDN number. The attached flow chart suggests commands that should assist with determining the root of the problem: