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Cisco Bug: CSCua99861 - persistently unreachable adjacencies cause higher CPU in 3.3.0SG

Last Modified

Feb 28, 2018

Products (1)

  • Cisco Catalyst 4500 Series Switches

Known Affected Releases


Description (partial)


CPU is high due in large part to "IP Input".  Sub-second protocol neighborships may flap.


Catalyst 4k switch running 15.1(1)SG / 3.3.0SG, 15.1(1)SG1 / 3.3.1SG or 15.1(1)SG2 / 3.3.2SG
A large amount of ARP resolution is occurring (possibly to due to a network subnet scan)

Related Community Discussions

Hello Support Please inform me on how to prevent high cpu ulization on a cisco device. An example is a cisco 4500X switch with a sample of the configs shown below. BRM_HQ_CSW_01#sh proc cpu sort Core 0: CPU utilization for five seconds: 1%; one minute: 4%; five minutes: 23% Core 1: CPU utilization for five seconds: 99%; one minute: 70%; five minutes: 56% PID   Runtime(ms) Invoked uSecs 5Sec     1Min     5Min     TTY   Process 8418   120346     280131   429   49.94   36.36   28.11  0     iosd              ...
Latest activity: Sep 02, 2019
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