PDN Gateway Overview
Features and Functionality - Base Software ▀
Cisco ASR 5x00 Packet Data Network Gateway Administration Guide ▄
67
configured Network Element types received by the S-GW. Trace configuration can be specified or transferred in any of
the following message types:
S5/S8: Create Session Request
S5/S8: Modify Bearer Request
S5/S8: Trace Session Activation (New message defined in TS 32.422)
Performance Goals
: As subscriber level trace is a CPU intensive activity the max number of concurrently monitored
trace sessions per Cisco P-GW is 32. Use in a production network should be restricted to minimize the impact on
existing services.
3GPP tracing was enhanced in StarOS Release 15.0 to increase the number of simultaneous traces to 1000. The
generated trace files are forwarded to external trace collection entity at regular intervals through (S)FTP if “push” mode
is enabled. If the push mode is not used, the files are stored on the local hard drive and must be pulled off by the TCE
using FTP or SFTP.
Important:
The number of session trace files generated would be limited by the total available hard disk
capacity.
3GPP Tracing to Intercept Random Subscriber
Previously, a subscriber identifier like IMSI was required in order to enable trace. Sometimes operators want to enable a
trace without knowing the subscriber ID. For example, an operator may want to monitor the next “n” number of calls, or
monitor subscribers in a particular IMSI range. The InTracer tool allows these use cases.
3GPP tracing was enhanced in StarOS Release 15.0 to intercept random subscribers with this feature. The current
session trace feature is either signaling or management based, which is very specific to a particular subscriber. The
requirement is to trace random subscribers which are not explicitly linked or identified by IMSI in GTP messages or
configured through CLI.
The random subscribers could be in an IMSI range, context activation in particular time intervals, etc.
The session trace is activated on demand for a limited period of time for specific analysis purposes. The maximum limit
would restrict the number of random subscriber tracing. Random session trace will be given priority over signalling and
management-based session trace.
Threshold Crossing Alerts (TCA) Support
Thresholding on the system is used to monitor the system for conditions that could potentially cause errors or outage.
Typically, these conditions are temporary (i.e high CPU utilization, or packet collisions on a network) and are quickly
resolved. However, continuous or large numbers of these error conditions within a specific time interval may be
indicative of larger, more severe issues. The purpose of thresholding is to help identify potentially severe conditions so
that immediate action can be taken to minimize and/or avoid system downtime.
The system supports Threshold Crossing Alerts for certain key resources such as CPU, memory, IP pool addresses, etc.
With this capability, the operator can configure threshold on these resources whereby, should the resource depletion
cross the configured threshold, a SNMP Trap would be sent.
The following thresholding models are supported by the system:
Alert
: A value is monitored and an alert condition occurs when the value reaches or exceeds the configured high
threshold within the specified polling interval. The alert is generated then generated and/or sent at the end of
the polling interval.
