Connectrix: MDS switch with CFS ipv4/ipv6 enabled reloads unexpectedly.
Summary: MDS switch with CFS ipv4/ipv6 enabled reloads unexpectedly.
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Symptoms
In rare circumstances, a MDS fabric switch may unexpectedly reload. In certain situations, the switch may subsequently enter into a continuous boot loop (see Further Problem Description for recovery steps in this case).
The reason for the reload is Kernel Panic.
`show system reset-reason`
----- reset reason for module 1 (from Supervisor in slot 1) ---
1) At 875120 usecs after Wed Sep 23 11:29:06 2020
Reason: Kernel Panic
Service:
Version: 8.4(1a)
This issue may happen only in the following circumstances:
By far, the most common use case for CFS distribution over ipv4/ipv6 is NPV mode, as in that configuration CFS distribution over FC is not supported. Since NPV mode is not supported on MDS 9250i, this software defect is less likely to occur on this, than on the other two affected platforms. One topology where it could still be implicated would be MDS 9250i as core switch with one or more NPV switches downstream.
The reason for the reload is Kernel Panic.
`show system reset-reason`
----- reset reason for module 1 (from Supervisor in slot 1) ---
1) At 875120 usecs after Wed Sep 23 11:29:06 2020
Reason: Kernel Panic
Service:
Version: 8.4(1a)
This issue may happen only in the following circumstances:
- Switch model is one of the following:
* MDS 9148S
* MDS 9396S
* MDS 9250i
* MDS 9396S
* MDS 9250i
- CFS distribution over ipv4 or ipv6 is configured on the switch:
cfs ipv4 distribute
cfs ipv6 distribute
cfs ipv6 distribute
By far, the most common use case for CFS distribution over ipv4/ipv6 is NPV mode, as in that configuration CFS distribution over FC is not supported. Since NPV mode is not supported on MDS 9250i, this software defect is less likely to occur on this, than on the other two affected platforms. One topology where it could still be implicated would be MDS 9250i as core switch with one or more NPV switches downstream.
Cause
Cisco NX-OS bug - CSCvs87512
Resolution
Resolution:
Upgrade to NX-OS 8.4.2a
Workaround:
Upgrade to NX-OS 8.4.2a
Workaround:
- If the affected device is running in NPV mode, disable CFS distribution completely.
config t
no cfs distribute
no cfs ipv4 distribute
no cfs ipv6 distribute
no cfs distribute
no cfs ipv4 distribute
no cfs ipv6 distribute
- If the affected device is running in switch mode, disable CFS distribution over ipv4/ipv6.
config t
no cfs ipv4 distribute
no cfs ipv6 distribute
no cfs ipv4 distribute
no cfs ipv6 distribute
Affected Products
Connectrix MDS-9148S, Connectrix MDS-9250i, Connectrix MDS-9396SArticle Properties
Article Number: 000181696
Article Type: Solution
Last Modified: 11 Mar 2021
Version: 1
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