Broadcast filtering enables you to filter out broadcast traffic such as ARP storms or UDP broadcasts. By eliminating excessive broadcast traffic at the network interface level rather than within the MCP host, you can free up the MCP processor for its normal workload and prevent a Denial of Service from being imposed on the MCP host.
Use the NW TCPIP BROADCASTFILTER command to enable, disable, and inquire about the configuration of broadcast filtering. You can specify high and low threshold values with this command so that if the number of broadcast packets received per second from the network is higher than the high threshold, all broadcast packets will be filtered (not processed) until the rate drops below the low threshold value.
| Note: | This command does not apply to IPv6 traffic because broadcasts are not supported in IPv6. |
For example, suppose you use the command to set the high threshold at 800 and the low threshold at 400. If the rate of broadcast packets received per second rises to 801 (or any rate above 800), broadcast filtering is enabled. If the rate then decreases to 700, broadcast filtering remains enabled. If the rate drops further to 399 (or any rate below 400), broadcast filtering is disabled and remains so until the rate again rises above 800.
Enter the following command to enable broadcast filtering:
NW TCPIP BROADCASTFILTER ENABLE [HIGHTHRESHOLD <threshold> LOWTHRESHOLD <threshold>]
The variable is described as follows.
|
Variable |
Description |
|---|---|
|
<threshold> |
The threshold values of packets received per second (high and low) for which broadcast filtering is enabled or disabled. You must specify both the high and low threshold values, or no values at all. If you enter this command without specifying thresholds, the default value is 1000 for high threshold and 500 for low threshold. |
Enter the following command to disable broadcast filtering:
NW TCPIP BROADCASTFILTER DISABLE
If you enter the TCPIP BROADCASTFILTER command without an ENABLE or DISABLE selection, the command serves as an inquiry and returns the current configuration of the broadcast filtering feature.
Refer to the Networking Commands and Inquiries Help for additional details on the syntax and usage of this command.
