Use Trace to Examine IS-IS Control Packets

Use trace as a debug tool to examine the code flow and Intermediate-System-to-Intermediate-System (IS-IS) control packets.

About this task

The default trace settings for CPU utilization are:

Enter Privileged EXEC mode:

enable
Identify the module ID for which you want to use the trace tool:

show trace modid-list
Clear any previous trace:

clear trace
Begin the trace operation:

trace level [<Module_ID>] [<0-4>]
Wait approximately 30 seconds.
Stop tracing:

trace shutdown
View the trace results:

trace screen enable

Important

If you use trace level 3 (verbose) or trace level 4 (very verbose), do not use the screen to view commands due to the volume of information the system generates and the effect on the system.
Optional: Save the trace file.

save trace [file WORD<1–99>]

If you do not specify a file name, the file name is systrace.txt.
Optional: Display trace lines saved to a file:

show trace file [tail]
Optional: Search trace results for a specific string value:

trace grep [WORD<0-128>]

If you use this command and do not specify a string value, you clear the results of a previous search.

Clear prior trace information, and then enable the display of trace output to the screen. Begin the trace operation for received IS-IS hello packets:

Switch:1#clear trace 
Switch:1>enable 
Switch:1#trace screen enable 
Switch:1#Screen tracing is on
Switch:1#trace level 267 2

The following table defines parameters for the show trace command.


Variable	Value
auto	Displays the current configuration for the automatic trace function.
file [tail]	Displays the trace results saved to a file.
level	Displays the current trace level for all modules.
modid-list	Specifies the module ID list.

The following table defines parameters for the trace command.


Variable	Value
grep `[WORD<0-128>]`	Specifies the search keyword. You can use a specific MAC address. You can search for errors, using the command, trace grep error.
level [`<Module_ID>`] `[<0-4>]`	Starts the trace by specifying the module ID and level. `<Module_ID>` specifies the module for the trace. Different hardware platforms support different IDs because of feature support differences. For feature support information, see Fabric Engine and VOSS Feature Support Matrix. To see the list of module IDs, use the show trace modid-list command or CLI command completion Help. 0–4 specifies the trace level: 0 — Disabled 1 — Very terse 2 — Terse 3 — Verbose 4 — Very verbose
shutdown	Stops the trace operation.
screen {disable\|enable}	Enables or disables the display of trace output to the screen. Important: Avoid using the screen to view commands if you use trace level 3 (verbose) or trace level 4 (very verbose) due to the volume of information generated and the effect on the system.

The following table defines parameters for the save trace command.


Variable	Value
file `WORD<1–99>`	Specifies the file name in one of the following formats: a.b.c.d: <file> WORD<1–99> is a string of 1–99 characters. Note: If you do not specify a file name, the file name is systrace.txt.