Tracing L2TP Operations for Subscriber Access

The Junos OS trace feature tracks L2TP operations and records events in a log file. The error descriptions captured in the log file provide detailed information to help you solve problems.

Note: This topic refers to tracing L2TP operations on MX Series routers. To trace L2TP operations on M Series routers, see Tracing L2TP Operations.

1. Important events are logged in a file located in the /var/log directory. By default, the router uses the filename jl2tpd. You can specify a different filename, but you cannot change the directory in which trace files are located.
2. When the trace log file filename reaches 128 kilobytes (KB), it is compressed and renamed filename.0.gz. Subsequent events are logged in a new file called filename, until it reaches capacity again. At this point, filename.0.gz is renamed filename.1.gz and filename is compressed and renamed filename.0.gz. This process repeats until the number of archived files reaches the maximum file number. Then the oldest trace file—the one with the highest number—is overwritten.

   You can optionally specify the number of trace files to be from 2 through 1000. You can also configure the maximum file size to be from 10 KB through 1 gigabyte (GB). (For more information about how log files are created, see the Junos OS System Log Messages Reference.)

By default, only the user who configures the tracing operation can access log files. You can optionally configure read-only access for all users.

1. (Optional) Configure a trace log filename.

   See Configuring the L2TP Trace Log Filename.

2. (Optional) Configure the number and size of trace logs.

   See Configuring the Number and Size of L2TP Log Files.

3. (Optional) Configure user access to trace logs.

   See Configuring Access to the L2TP Log File.

4. (Optional) Configure a regular expression to filter the information to be included in the trace log.

   See Configuring a Regular Expression for L2TP Messages to Be Logged.

5. (Optional) Configure flags to specify which events are logged.

   See Configuring the L2TP Tracing Flags.

6. (Optional) Configure a severity level for messages to specify which event messages are logged.

   See Configuring the Severity Level to Filter Which L2TP Messages Are Logged.