The documents explicitly state that the SDA L2 border switch (C9500) was running the older code '16.12.1s,' which caused ARP flooding and L2 forwarding issues. The problem was resolved after upgrading to '17.6.4,' but the principal discussion focuses on the version with the defect ('16.12.1s').
The issue occurred on software version 16.12.1s, leading to L2 forwarding failures. Upgrading to 17.6.4 resolved the problem.