Understanding Traffic Suppression

Traffic suppression restricts broadcast, multicast, and unicast packets in the following three modes:

Interface view

Controls the bandwidth percentage, packets per second, and bits per second of incoming broadcast packets, unknown multicast packets, unknown unicast packets, known multicast packets, and known unicast packets.

A switch monitors rates of these packets on the interface and compares the rates with the thresholds. When the rate of incoming traffic reaches the threshold, the switch discards excess traffic.
Outbound interface view

Blocks outgoing broadcast packets, unknown multicast packets, and unknown unicast packets.
VLAN view

Limits the bits per second for broadcast packets.

A switch monitors broadcast packet rates in the same VLAN and compares the rates with the thresholds. When the traffic rate in the VLAN reaches the threshold, the switch discards excess traffic.

Traffic suppression can also limit the rate of ICMP packets by setting a threshold. A large number of ICMP packets may be sent to the CPU without traffic suppression. When this happens, other service functions may become abnormal.

By default, the device supports traffic suppression triggered by MAC address flapping. When MAC address flapping detection is enabled, traffic suppression will be triggered on the interface where MAC address flapping occurs. That is, the rate of unknown unicast packets is limited to 50% of the interface bandwidth.

If traffic suppression on unknown unicast packets is configured using the unicast-suppression command and the rate limit of unknown unicast packets is not 100% of the interface bandwidth, or storm control on unknown unicast packets is configured using the storm-control command, traffic suppression will not be triggered on an interface where MAC address flapping occurs.