Using 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. When you enable IS-IS trace flags, the system displays only trace information about the set flag.

Before you begin

You must know what you want to trace before you enable trace.

Procedure

Enter Privileged EXEC mode:

enable
Enable the Intermediate-System-to-Intermediate-System trace flags:

trace flags isis set { none | tx-hello | rx-hello | tx-pkt | rx-pkt | adj | opt | tx-lsack | rx-lsack | tx-lsp | rx-lsp | pkt-err | nbr-mismatch | flood | prefix | nbr-change | intf-change | decide | fdb | dr | dd-masterslave | auth-fail | config | purge | policy | redist | tx-snp | rx-snp | timer | global | perf | ucast-fib | node | mcast-fib | isid | ip-shortcut }
Identify the module ID for which you want to use the trace tool:

show trace modid-list
Clear the trace:

clear trace
Begin the trace operation:
trace level [<Module_ID>] [<0-4>]

OR

trace spbm isis level [<0-4>]

OR

trace cfm level [<0-4>]
Note
- Module ID 119 represents the IS-IS module.
Wait approximately 30 seconds.
The default trace settings for CPU utilization are:
- High CPU Utilization: 90%
- High Track Duration: 5 seconds
- Low CPU Utilization: 75%
- Low Track Duration: 5 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.
Save the trace file.

save trace [file WORD<1–99>]

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

show trace file [tail]
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.
Stop tracing:

trace shutdown
Disable the Intermediate-System-to-Intermediate-System trace flags:

trace flags isis remove { none | tx-hello | rx-hello | tx-pkt | rx-pkt | adj | opt | tx-lsack | rx-lsack | tx-lsp | rx-lsp | pkt-err | nbr-mismatch | flood | spf-intra | spf-inter | spf-extern | prefix | nbr-change | intf-change | decide | fdb | dr | dd-masterslave | auth-fail | config | purge | policy | redist | tx-snp | rx-snp | timer | spbm-decide | global | perf | ucast-fib | node | mcast-fib | isid | ip-shortcut }

Example

Switch:1> enable

Clear prior trace information:

Switch:1# clear trace

Enable IS-IS trace flags for received IS-IS hello packets:

Switch:1# trace flags isis set rx-hello

Enable IS-IS trace flags for transmitted IS-IS hello packets:

Switch:1# trace flags isis set tx-hello

Configure the module ID to 119 (IS-IS module) and the trace to 4 (very verbose):

Switch:1# trace level 119 4

Enable the display of trace output to the screen:

Switch:1# trace screen enable

Switch:1# Screen tracing is on

Disable the display of trace output to the screen:

Switch:1# trace screen disable

Switch:1# Screen tracing is off

Variable Definitions

The following table defines parameters for the trace flags isis command.


Variable	Value
remove `{ none \| tx-hello \| rx-hello \| tx-pkt \| rx-pkt \| adj \| opt \| tx-lsack \| rx-lsack \| tx-lsp \| rx-lsp \| pkt-err \| nbr-mismatch \| flood \| prefix \| nbr-change \| intf-change \| decide \| fdb \| dr \| auth-fail \| config \| purge \| policy \| redist \| tx-snp \| rx-snp \| timer \| global \| perf \| ucast-fib \| node \| isid \| ip-shortcut }`	Removes the Intermediate-System-to-Intermediate-System (IS-IS) trace flags for the specified option.
set `{ none \| tx-hello \| rx-hello \| tx-pkt \| rx-pkt \| adj \| opt \| tx-lsack \| rx-lsack \| tx-lsp \| rx-lsp \| pkt-err \| nbr-mismatch \| flood \| prefix \| nbr-change \| intf-change \| decide \| fdb \| dr \| auth-fail \| config \| purge \| policy \| redist \| tx-snp \| rx-snp \| timer \| global \| perf \| ucast-fib \| node \| isid \| ip-shortcut }`	Enables the Intermediate-System-to-Intermediate-System (IS-IS) trace flags for the specified option. none — none tx-hello — Transmitted IS-IS hello packet rx-hello — Received IS-IS hello packet tx-pkt — Transmitted packet rx-pkt — Received packet adj — Adjacencies opt — IS-IS TLVs tx-lsack — Transmitted LSP acknowledgement rx-lsack — Received LSP acknowledgement tx-lsp — Transmitted Link State Packet rx-lsp — Received Link State Packet pkt-err — Packet Error nbr-mismatch — Neighbor mismatch flood — Flood prefix — Prefix nbr-change — Neighbor change intf-change — IS-IS circuit (interface) events decide — Shortest Path First computation fdb — Filtering Database dr — Designated Router auth-fail — Authorization failed config — Configuration purge — Link State Packet purge redist — Redistribute tx-snp — Transmitted Sequence Number PDU (CSNP and PSNP) rx-snp — Received Sequence Number Packet (CSNP and PSNP) timer — Timer perf — SPBM performance ucast-fib — Unicast Forwarding Information Base node — Node isid — I-SID ip-shortcut — IP Shortcut

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.
cfm level `[<0-4>]`	Starts tracing by CFM. <0-4> specifies the trace level from 0–4, where 0 is disabled; 1 is very terse; 2 is terse; 3 is verbose, 4 is very verbose.
spbm isis level `[<0-4>]`	Specifies exactly which IS-IS component to display. <0-4> specifies the trace level from 0–4, where 0 is disabled; 1 is very terse; 2 is terse; 3 is verbose, 4 is very verbose.
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 ID ranges because of feature support differences. To see which module IDs are available on the switch, 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.