DAD interface down on stackwise virtual 9500 16X

[yum3372]

Hello guys,

I got some weird case on my 9500 virtual stacks. I have multiple 9500-16X and they are in stackwise virtual as a pair. On 2 pairs of mine, DAD interfaces are showing down. Their IOS version is 17.12.04, is there any bug related with this symptom? And is there any impact on switch operation if I bounce the DAD interfaces? The switches should not go down due to production.

Cisco IOS XE Software, Version 17.12.04
Cisco IOS Software [Dublin], Catalyst L3 Switch Software (CAT9K_IOSXE), Version 17.12.4, RELEASE SOFTWARE (fc3)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2024 by Cisco Systems, Inc.
Compiled Tue 23-Jul-24 09:40 by mcpre

In dual-active recovery mode: No
Recovery Reload: Enabled

Dual-Active-Detection Configuration:
-------------------------------------
Switch Dad port Status
------ ------------ ---------
1 TenGigabitEthernet1/0/16 down
2 TenGigabitEthernet2/0/16 down

[Mark Elsen]

  - @yum3372              Check logs on the switch too and look for anomalies 

  M.

[yum3372]

Hello Mark,

I looked at logs and found nothing related to it. And I figured out that port couldn't recognize a SFP module. I've replaced the module serveral times, but it's showing unknown as same. Is it possible to be a hardwear problem on the port?

Te1/0/16 ## STACKWISE VIRTU notconnect 4094 full auto unknown

[Mark Elsen]

  - @yum3372                     Note sure, I advice to contact TAC

  M.

[MHM Cisco World]

• DAD and SVL can only be configured on specific supported interfaces. Not all switch ports support DAD/SVL configuration, so please verify that the selected ports are supported for this purpose.
• If the SFP is not being recognized, please check whether it is a third-party transceiver. If so, on Cisco switches you may need to disable the SFP compatibility check (where supported by the platform and software version).
• To determine whether the issue is physical-layer related or caused by a higher-layer configuration problem, check the SFP operational parameters, including optical transmit/receive power levels and temperature. Abnormal values may indicate a faulty transceiver, fiber issue, or optical signal problem.

[balaji.bandi · Accepted solution]

There are known bugs matching your exact symptom on the 17.12 train, but the good news is that bouncing the DAD interfaces is completely safe and will not impact your production data traffic.

https://bst.cisco.com/quickview/bug/CSCwh25704

[yum3372 · Accepted solution]

Thanks for your answer. Unfortunately DAD interfaces do not allow boucing, so I reinserted the module physically. And it went up back. Probably just SFP module issue.

[balaji.bandi]

Sure, reseating option also considers port bounce, good to know all is good.