Filtering index
The switch automatically assigns each new filter
to the lowest-available index (IDX) number. The index numbers are
included in the show filter
command described in
the next section and are used with the show filter <index>
command
to display detailed information about a specific filter.
If there are no filters currently configured, and you create three filters in succession, they will have index numbers 1-3. However, if you then delete the filter using index number “2” and then configure two new filters, the first new filter will receive the index number “2” and the second new filter will receive the index number "4". This is because the index number “2” was made vacant by the earlier deletion, and was therefore the lowest index number available for the next new filter.