Symptom

Applicable to all F2 (Clipper/Clipper CR) based cards. Congestion seen on ingress traffic on some/all of the ports. This is because, frames are stuck in the IB caused due to bad acos to ccos table. To confirm if the issue is due to bad table, please compare the acos to ccos mapping in the below commands show hardware internal qengine inst x vq acos_ccos_4cl/acos_ccos_8cl compare it with the ccos mapping in show hardware internal qengine inst x table fr_dcx4q_oq_ccos/fr_dcx8q_oq_ccos if the acos to ccos mapping are different, then the Credit Loop logic will affected and frames will be stuck in the IB resulting in congestion on the ingress ports.

Conditions

Do ISSU and then VDC reload (VDC containing ports from F2 LC). This is because, the shadow memory in our Qengine driver was corrupted during ISSU and VDC reload causes a shadow refresh to the HW. If customer has performed the ISSU from impacted version to a fixed version, issue will still remain. Customer need to perform the LC or switch reload

Workaround

1. Reload the line card OR 2. Reload the chassis

Further Problem Description

Fix-Remarks

If the problem is present on the switch and ISSU is performed to the software version with the fix, the problem may not be resolved. Line card or switch reload is required after ISSU for the fix to become effective.