Symptom

The problem impacts the DHCP traffic because ICMP redirect CoPP queue can be overloded The access device is sending multicast traffic to a private IP destination According to the CPU debug, traffic is punted to create ICMP unreachable messages The destination interface is an SVI, but the status is administratively down The switch is acting like the First Hop Router instead of forwarding the multicast traffic

Conditions

C9606R running 17.06.03 SVI interface configuration SVI interface status is administratively down ICMP Redirect CPU Queue Statistics is increasing

Workaround

apply "no ip unreachables" under the interface

Further Problem Description