RackSwitch G8000 Application Guide
Chapter 6: Quality of Service
105BMD00041, November 2008
Using Storm Control Filters
The G8000 provides filters that can limit the number of the following packet types transmitted
by switch ports:
Broadcast packets
Multicast packets
Unknown unicast packets (destination lookup failure)
Broadcast storms
Excessive transmission of broadcast or multicast traffic can result in a broadcast storm.
A broadcast storm can overwhelm your network with constant broadcast or multicast traffic,
and degrade network performance. Common symptoms of a broadcast storm are slow network
response times and network operations timing out.
Unicast packets whose destination MAC address is not in the Forwarding Database are
unknown unicasts. When an unknown unicast is encountered, the switch handles it like a
broadcast packet and floods it to all other ports in the VLAN (broadcast domain). A high rate
of unknown unicast traffic can have the same negative effects as a broadcast storm.
Configuring storm control
Configure broadcast filters on each port that requires broadcast storm control. Set a threshold
that defines the total number of broadcast packets transmitted, in Megabits per second.
When the threshold is reached, no more packets of the specified type are transmitted.
To filter broadcast packets on a port, use the following commands:
To filter multicast packets on a port, use the following commands:
To filter unknown unicast packets on a port, use the following commands:
RS G8000 (config)# interface port 1
RS G8000 (config-if)# broadcast-threshold <packet rate (1-33554431)>
RS G8000 (config-if)# exit
RS G8000 (config)# interface port 1
RS G8000 (config-if)# multicast-threshold <packet rate (1-33554431)>
RS G8000 (config-if)# exit
RS G8000 (config)# interface port 1
RS G8000 (config-if)# dest-lookup-threshold <packet rate (1-33554431)>
RS G8000 (config-if)# exit
