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Cisco Bug: CSCvs34401 - Port-monitor generates txwait random falling-threshold alerts with constant R-RDY delay

Last Modified

May 04, 2020

Products (1)

  • Cisco MDS 9000 Series Multilayer Switches

Known Affected Releases

8.3(1) 8.3(2) 8.4(1a) 8.4(2.156)

Description (partial)

Randomly, on a slow port, a Port Monitor txwait falling threshold alert with 'value=0' is followed 1 second later by a txwait rising threshold alert. The following type of syslogs are logged:
    2019 Dec  2 16:22:35 mds9396t %PMON-SLOT1-3-RISING_THRESHOLD_REACHED: TXWait has reached the rising threshold (port=fc1/54 [0x1035000], value=96) .
    2019 Dec  2 16:24:07 mds9396t %PMON-SLOT1-3-FALLING_THRESHOLD_REACHED: TXWait has reached the falling threshold (port=fc1/54 [0x1035000], value=0) .
    2019 Dec  2 16:24:08 mds9396t %PMON-SLOT1-3-RISING_THRESHOLD_REACHED: TXWait has reached the rising threshold (port=fc1/54 [0x1035000], value=96) .

This issue only applies to MDS 9396T switches with constant transmit delay (constant receive R_RDY delay from peer). Other platforms are not affected.
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