Ref: 13390014
Title: Using Reverse Filtering for Multiple Protocol Networks
Date: 11/07/90

Copyright 3Com Corporation, 1991.  All rights reserved.

Following is an example of using reverse filters on a network that has
NBP/XNS, TCP and AARP (Appletalk Address Resolution Protocol), to allow TCP
and AARP on one segment of the network and NBP/XNS on another.

On the segment where you want NBP/XNS packets, use the following reverse
filters to allow only NBP/XNS packets to pass through the bridge:

   add filter !1 ~%C:%0600  (XNS packets)
   add filter !2 ~%C:%3C    (NBP packets)

Because these are reverse filters, all packets that meet the filter
criteria are forwarded.  All other packets are discarded.

Caution:  If you also use standard filters, make sure ALL standard filters
are executed BEFORE the reverse filters.  To further optimize the filtering
process, the most restrictive filters (those that block the most traffic)
should be executed before less restrictive filters.

