SNMP and CLEAR COUNTER on interfaces

Discussion in 'Cisco' started by Nadir Sahnoun, Jul 28, 2004.

  1. Hi all,

    i use Nagios 1.2 to check Errors IN and OUT on Cisco network interfaces by
    using check_snmp (snmpget) and i check returned data with GETIF to be sure
    that the result is the same. all work fine.

    i have some errors on Serial interfaces of routers. When i clear counter on
    all interfaces (clear counter) and i execute "show int" on the router, the
    errors number of IN/OUT is reseted to zero. OK, it's normal.

    But, Nagios (snmpget) and GETIF always get the old error IN/OUT number ! Why

    Thanks a lot

    @+ nadir
    Nadir Sahnoun, Jul 28, 2004
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  2. So that you can clear counters and not screw up any SNMP monitors which
    would interpret the negative jump as a wrap-around of the counter. You
    SNMP monitor should be showing you the rate of errors (an interesting
    number) rather than the absolute number (a worthless number, that's why
    you keep reseting the counter). If your monitor is not smart enough to
    convert polled values of uptime and errors (or whatever parameter you're
    monitoring) to useful rate values, it's time to replace the SNMP
    monitor with something intended to be used by humans.

    Good luck and have fun!
    Vincent C Jones, Jul 29, 2004
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  3. Thanks Vincent for your reponse.

    i found this note a bout clear counters command on cisco web :
    This command does not clear counters retrieved using Simple Network
    Management Protocol (SNMP), but only those seen with the show interface EXEC

    i will search more...

    @+ Nadir
    Nadir Sahnoun, Jul 29, 2004
  4. by reloading the router (2621), the MIB is updated (reseted)

    i need to find command CLI to do it without reboot the router

    ThankYou very much
    @+ nadir
    Nadir Sahnoun, Jul 29, 2004
  5. If you read the definition of the MIB value you are tracking,
    you will discover that it is defined as the number of errors since
    SNMP started. So to reset the counter you would need to shut down
    SNMP and then restart it. That way, all MIB values are set to zero,
    including system.uptime (which is really SNMP uptime).
    Vincent C Jones, Jul 29, 2004
  6. ok !

    so, how can i restart SNMP service on the router ?

    ThankYou very much

    @+ Nadir
    Nadir Sahnoun, Jul 29, 2004
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