Description

The virtual chassis is not formed after detached and attached 100G optics on QFX VC link. Initially it was working fine but after detached and attached that optics, VC doesn't get formed.
This is a software bug which has been fixed through PR1754838. This KB describes the details of this issue.

Symptoms

On QFX virtual-chassis sytem, VC doesn't get formed after detached and attached 100G VC cables or optics.
And after rebooting QFX, the issue would be resolved.
For example, when 100G DAC cable is used for VC link, that link won't came up.

<Topology>
QFX-A(et-0/0/52)--------VCP--------(et-0/0/52)QFX-B
-------------------- 
root@QFX-A> show chassis hardware | match 52
    Xcvr 52      REV 01   740-061000   AAAAAAAAAAAAA     QSFP28-100G-CU1M
    
labroot@QFX-B> show chassis hardware | match 52
    Xcvr 52      REV 01   740-061000   AAAAAAAAAAAAA     QSFP28-100G-CU1M
-------------------- 
root@QFX-A> show virtual-chassis vc-port
localre:
--------------------------------------------------------------------------
Interface   Type              Trunk  Status       Speed        Neighbor
or                             ID                 (mbps)       ID  Interface
PIC / Port
0/52        Configured         -1    Down         100000
-------------------- 
root@QFX-B> show virtual-chassis vc-port
localre:
--------------------------------------------------------------------------
Interface   Type              Trunk  Status       Speed        Neighbor
or                             ID                 (mbps)       ID  Interface
PIC / Port
0/52        Configured         -1    Down         100000
--------------------

Solution

This is a software bug which has been fixed through PR1754838. Please find the details from this PR.
https://prsearch.juniper.net/problemreport/PR1754838

Modification History

2023-10-16