Introduction - Cisco ASR 5000 Series Administration Manual

▀ Introduction

Introduction
The Subscriber Level Trace provides a 3GPP standards-based session-level trace function for call debugging and testing
new functions and access terminals in an LTE environment.
In general, the Session Trace capability records and forwards all control activity for the monitored subscriber on the
monitored interfaces. This is typically all the signaling and authentication/subscriber services messages that flow when a
UE connects to the access network.
The EPC network entities like MME, S-GW, P-GW support 3GPP standards based session level trace capabilities to
monitor all call control events on the respective monitored interfaces including S6a, S1-MME and S11 on MME, S5,
S8, S11 at S-GW and S5 and S8 on P-GW. The trace can be initiated using multiple methods:
Management initiation via direct CLI configuration
Management initiation at HSS with trace activation via authentication response messages over S6a reference
interface
Signaling based activation through signaling from subscriber access terminal
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interfaces.
The session level trace function consists of trace activation followed by triggers. The time between the two events is
treated much like Lawful Intercept where the EPC network element buffers the trace activation instructions for the
provisioned subscriber in memory using camp-on monitoring. Trace files for active calls are buffered as XML files
using non-volatile memory on the local dual redundant hard drives on the ASR 5000 platforms. The Trace Depth
defines the granularity of data to be traced. Six levels are defined including Maximum, Minimum and Medium with
ability to configure additional levels based on vendor extensions.
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The following figure shows a high-level overview of the session-trace functionality and deployment scenario:
▄ Cisco ASR 5000 Series Serving Gateway Administration Guide
:
Once the trace is provisioned it can be provisioned through the access cloud via various signaling
:
Only Maximum Trace Depth is supported in the current release.
Configuring Subscriber Session Tracing
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