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11.14 Tracing IS-IS Protocol Traffic<br />

Problem<br />

You are setting up IS-IS on your network and want to keep a running log of IS-IS<br />

protocol packets that the router is sending to help you track any problems that might<br />

occur during the configuration process.<br />

Solution<br />

Set up a tracing file that captures information about IS-IS protocol operations:<br />

[edit protocols isis]<br />

aviva@RouterJ# set traceoptions file isis-logs<br />

aviva@RouterJ# set traceoptions flag error<br />

aviva@RouterJ# set traceoptions flag general<br />

aviva@RouterJ# set traceoptions flag normal<br />

To stop the tracing, remove the traceoptions statement from the configuration:<br />

[edit protocols isis]<br />

aviva@RouterJ# delete traceoptions<br />

<strong>Discussion</strong><br />

To debug IS-IS operations, use the JUNOS tracing facility to track the packets that<br />

IS-IS is sending and receiving. You specify the name of the file to which you want to<br />

collect the information and the type of information you want to trace. In this example,<br />

we set three flags to track normal operations and errors in the file isis-logs, which<br />

is on the router’s hard disk in the directory /var/log (on M-series and T-series routers)<br />

and /cf/var/log (on J-series routers).<br />

When you are first bringing up an IS-IS network, you may find that an adjacency is<br />

not establishing between two Level 1 routers:<br />

aviva@RouterJ> show isis adjacency<br />

Interface System L State Hold (secs) SNPA<br />

fe-0/0/1.0 RouterF 1 Down 0 0:5:85:c1:86:31<br />

fe-1/0/0.0 RouterH 2 Up 22 0:5:85:c1:d1:f4<br />

fe-1/0/1.0 RouterG 2 Up 24 0:5:85:c2:2e:f5<br />

The logfile shows where the problem is:<br />

aviva@RouterJ> show log isis-logs | last<br />

Jun 25 12:47:15 ERROR: IIH from RouterG with no matching areas, interface fe-1/0/1.0<br />

Jun 25 12:47:15 local area 49.0050<br />

Jun 25 12:47:15 remote area 49.0020 (3 bytes)<br />

Jun 25 12:47:15 ERROR: IIH from RouterF with no matching areas, interface fe-0/0/1.0<br />

Jun 25 12:47:15 local area 49.0050<br />

Jun 25 12:47:15 remote area 49.0051 (3 bytes)<br />

This is the Title of the Book, eMatter Edition<br />

Copyright © 2008 O’Reilly & Associates, Inc. All rights reserved.<br />

Tracing IS-IS Protocol Traffic | 379

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