Re: Dual-Active detection Link Down on Virtual StackWise switches

Gabiche9 · ‎08-24-2018

Hello,

I am currently facing an issue on my Virtual StackWise switches.

We have two WS-C3850-48XS-E configured with Virtual Stackwise.

There are two Virtual Stackwise Links of 10G as part of the SVL domain 1.

There is one fiber link 1G for Dual Active detection. The protocol is Fast-Hello.

We recently lost the Fast-Hello Link. I'm not confident of letting the switches in this state because split brain can now occur.

I tried to fix the Fast-Hello link but it doesn't want to be in Up state. The fiber has been check between the switches.

Do you know if the only way to get this link up is through a reboot of the switches ?

Any help would be really appreciated. You can find below the configuration of the Stackwise Link.

Thank you

switch#sh stackwise-virtual dual-active-detection
Dual-Active-Detection Configuration:
-------------------------------------
Switch Dad port
------ ------------
1 TenGigabitEthernet1/0/44
2 TenGigabitEthernet2/0/44

switch#sh int te1/0/44
TenGigabitEthernet1/0/44 is down, line protocol is down (notconnect)

switch#sh stackwise-virtual link
Stackwise Virtual Link(SVL) Information:
----------------------------------------
Flags:
------
Link Status
-----------
U-Up D-Down
Protocol Status
---------------
S-Suspended P-Pending E-Error T-Timeout R-Ready
-----------------------------------------------
Switch SVL     Ports                           Link-Status     Protocol-Status
------ ---     -----                           -----------     ---------------
1       1       TenGigabitEthernet1/0/45        U               R
                TenGigabitEthernet1/0/46        U               R
2       1       TenGigabitEthernet2/0/45        U               R
                TenGigabitEthernet2/0/46        U               R

switch#sh run int t1/0/44
Building configuration...

Current configuration : 112 bytes
!
interface TenGigabitEthernet1/0/44
stackwise-virtual dual-active-detection
description Fast-Hello Link
end

andresfr · ‎08-24-2018

Hello Gabiche,

Have you already try bouncing (shut/no shut) interfaces TenGigabitEthernet1/0/44 and TenGigabitEthernet2/0/44? What about defaulting those two interfaces and re-configuring them as dual-active link?

conf t

default interface TenGigabitEthernet1/0/44

default interface TenGigabitEthernet2/0/44

interface TenGigabitEthernet1/0/44

stackwise-virtual dual-active-detection

exit

!

interface TenGigabitEthernet2/0/44

stackwise-virtual dual-active-detection

end

!

If bouncing the those ports do not solve the problem, you'll have to reload/restart the switch. Is there are no issues with the stackwise virtual link, that should not be a problem.

Regards,

Gabiche9 · ‎08-27-2018

Hello Andres,

Thank you very much for your reply.

Unfortunately the switch doesn't accept neither the default command nor the shutdown command:

switch(config)#default interface t1/0/44
% Error, TenGigabitEthernet1/0/44 is a distributed stack inferface, default configuration will not be accepted

(misprint in the switch for "inferface" :) )

With the "no stackwise" command:

switch(config-if)#no stackwise-virtual dual-active-detection
WARNING: Stackwise Virtual Dual Active Detection Configuration for TenGigabitEthernet1/0/44 will be removed on reboot.
switch(config-if)#stackwise-virtual dual-active-detection
WARNING: All the extraneous configurations will be removed for TenGigabitEthernet1/0/44 on reboot.

switch(config)#int t1/0/44
switch(config-if)#shutdown
^
% Invalid input detected at '^' marker.

So it seems the reboot is mandatory to include again a Dual-Active Detection link in the Virtual Stackwise.

The reboot seems understanding for a Virtual Stackwise Link, but I would have not expect this for the Fast Hello Link.

By the way, I will take advantage of the reboot operation to add a second Fast-Hello link with a different Fiber path and avoid this situation again.

I will keep you informed after the reboot and close this thread in the meantime.

Thank you !

jjfaure · ‎10-01-2018

Hi Gabiche,

Do you solved this DAD issue ? Could you remove physical DAD interfaces? I have a similar issue using virtual stackwise and DAD : i have some ports that i would like to dissasociate from DAD but systems does not allow.

Regards

GabSCHPro · ‎11-13-2018

Hello,

The only way to remove / include a DAD link or a SVL is to reboot the entire core (both 3850).

Concerning my issue, it may have been solved with the newest OS release.

Please note that I did not find this issue with 9500 serie switch.

Regards,

cjjones · ‎11-19-2019

This does also happen on 9500s. I have a pair that rebooted due to a memory leak bug and DAD didn't come back up. At least when I upgrade the ios and reboot, hopefully the DAD links will come back up!

Fo2/0/23 DAD link to Fo1/0/ notconnect 4094 full 40G QSFP 40G SR BD SFP
Fo2/0/24 DAD link to Fo1/0/ notconnect 4094 full 40G QSFP 40G SR BD SFP

jjfaure · ‎10-01-2018

Hi Gabiche,

Do you solved this DAD issue ? Could you remove physical DAD interfaces? I have a similar issue using virtual stackwise and DAD : i have some ports that i would like to dissasociate from DAD but systems does not allow.

Regards

GabSCHPro · ‎11-27-2019

Hi jjfaure,

The DAD still appears not stable, and when it goes down the only way to get it back up is to reboot the entire Core.

If you want to remove a DAD configuration from a port:

switch(config-if)#no stackwise-virtual dual-active-detection
WARNING: Stackwise Virtual Dual Active Detection Configuration for TenGigabitEthernet1/0/44 will be removed on reboot.

Then you have to reboot the entire Core.

Best regards,