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Cisco Nexus 7000 Series Switches

Field Notice: FN - 63280 - Nexus 7000 May Encounter an Unexpected Supervisor Switchover or Reload Due to High Availability Policy for Diagnostic Service

Field Notice: FN - 63280 - Nexus 7000 May Encounter an Unexpected Supervisor Switchover or Reload Due to High Availability Policy for Diagnostic Service

September 30, 2009


NOTICE:

THIS FIELD NOTICE IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTY OF MERCHANTABILITY. YOUR USE OF THE INFORMATION ON THE FIELD NOTICE OR MATERIALS LINKED FROM THE FIELD NOTICE IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS FIELD NOTICE AT ANY TIME.

Revision History

Revision Date Comment
1.0
30-SEP-2009
Initial Public Release

Products Affected

Products Affected
N7000 NX-OS - 4.2(1)
N7000 NX-OS - 4.2(2)

Problem Description

Two specific diagnostic tests on the Nexus 7000 can cause an unexpected process error due to a slow resource leak resulting in two scenarios:

1) A supervisor switchover due to the high availability (HA) policy for service diag_port_lb, when dual supervisors are present

2) A system reload due to HA policy for service diag_port_lb, when only a single supervisor is present

This unexpected process error is documented in CSCtc17493.

Background

The NX-OS software supports a Generic Online Diagnostic (GOLD) feature that proactively monitors the health of the switch. For this particular issue, there are two particular diagnostic tests that are affected and would need to be disabled in order to avoid this situation in the 4.2(1) and 4.2(2) releases:

1) The GOLD PortLoopback test. This test is enabled by default as health monitoring. Any ports that fail the loopback test stay in the error-disabled state and are not available for configuration.

2) The StandbyFabricLoopback test. This is a health monitoring test that is enabled by default, designed to verify the integrity of the data path between the Standby supervisor and the Fabric. The diagnostic has the flexibility to define the action on failure: syslog (default action), onboard diagnostic failure logging, supervisor switchover. Multiple actions can be simultaneously triggered. Before Cisco NX-OS Release 4.2(1), such a health monitoring test was supported only for the active supervisor in the chassis.

Problem Symptom

An unexpected supervisor switchover or system reload may occur on the Nexus 7000 switch.

Workaround/Solution

Solution:

CSCtc17493 can be resolved by upgrading to NX-OS release 4.2(2a). NX-OS release 4.2(2a) can be downloaded from the NX-OS system software page (registered customers only).

Workaround:

If upgrading the NX-OS software is not a viable option, there is a workaround for CSCtc17493.

Disable the periodic packet loopback tests. Please note that disabling these tests does not affect normal functioning of the device.

Disable these tests by entering the following commands:

1) Enter the following command on each of the modules that are present on the device (for line cards only, not applicable to supervisors):
(config)# no diagnostic monitor module < x > test 5,6

2) Enter the following command to disable the bootup diagnostics:
(config)# diagnostic bootup level bypass

3) Enter the following command to save the configuration to startup-config:
(config)# copy running-config startup

Descriptions of these tests (test 5 and test 6) are given below:

switch# show diagnostic description module 1 test 5
A health monitoring test that will test the packet path from the Supervisor card to the physical port in ADMIN DOWN state on Linecards.

switch# show diagnostic description module 1 test 6
A health monitoring test, enabled by default, that does nondisruptive loopback for all LC ports up to the Rewrite Engine.

DDTS

To follow the bug ID link below and see detailed bug information, you must be a registered customer and you must be logged in.

DDTS Description
{CSCtc17493} (registered customers only) Nexus 7000 May Encounter an Unexpected Supervisor Switchover or Reload Due to High Availability Policy for Diagnostic Service

For More Information

If you require further assistance, or if you have any further questions regarding this field notice, please contact the Cisco Systems Technical Assistance Center (TAC) by one of the following methods:

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