Configuring a filter on a port trunk

This operation uses the same command as is used for configuring a filter on an individual port. However, the configuration process requires two steps:

  1. Configure the port trunk.

  2. Configure a filter on the port trunk by using the trunk name (trk1, trk2, ...trk6) instead of a port name.

For example, to create a filter on port trunk 1 to drop traffic received inbound for trunk 2 and ports 10-15:

switch(config)# filter source-port trk1 drop trk2,10-15

Note that if you first configure a filter on a port and then later add the port to a trunk, the port remains configured for filtering but the filtering action will be suspended while the port is a member of the trunk. That is, the trunk does not adopt filtering from the port configuration. You must still explicitly configure the filter on the port trunk. If you use the show filter <index> command for a filter created before the related source port was added to a trunk, the port number appears between asterisks ( * ), indicating that the filter action has been suspended for that filter. For example, if you create a filter on port 5, then create a trunk with ports 5 and 6, and display the results, you would see the following:

Switch response to adding a filtered source port to a trunk