Dear Folks, Routing protocols like OSPF maintain neigbour relationships with other routers in the area by exchanging periodic hello messages.
This can be used as a means of very quickly detecting router reachabily failures because the hello messages typically occur several times a minute and a failure is detected in less than a minute. OSPF routers report a neighbour failure with messages like 155795 bar syslog-notice 2006-08-02 01:40:49 134777: %OSPF-5-ADJCHG: Process 1, Nbr baz on Tunnel0 from FULL to DOW N, Neighbor Down: Dead timer expired 155796 foo syslog-notice 2006-08-02 01:40:49 231: Aug 1 15:40:49: %OSPF-5-ADJCHG: Process 1, Nbr baz on Tunnel0 fro m FULL to DOWN, Neighbor Down: Dead timer expired In this case, there is an OSPF broadcast network with DRs bar and foo. The Neighbour baz is reported as having failed to respond to poll (after 10 failures to respond ie 40 seconds). The DRs both report the failure within 30 seconds of each other. The way to to detect such failures in real time is with an event correlation tool like SEC. A very good introduction to the challenges of event correlation and how to deal with them using SEC is John Rouillards paper at http://www.cs.umb.edu/~rouilj/sec/sec_paper.pdf In this case the challenges include 1 detecting the pair of messages within a time interval of each other 2 allowing a delay interval for the neighbour to recover before notifying 3 notifying on recovery. SEC allows a rich set of actions to be performed when it detects an event. These include running programs such as a mail client or ssh to submit a passive service check result. Yours sincerely. ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Nagios-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/nagios-users ::: Please include Nagios version, plugin version (-v) and OS when reporting any issue. ::: Messages without supporting info will risk being sent to /dev/null
