
Introduction
Transparent mode essentially turns a layer-3 firewall into a “transparent,” layer-2
“bump in a wire.” An architect may be reluctant to alter the routing by adding a hop
and modifying the layer-3 topology of her environment because of functional
requirements, or for convenience.To implement a layer-2 device, all she needs is to
schedule an outage and move some cables, and the transparent firewall deployment is
akin to dropping such a bridge or switch (a multiport bridge in its own right) into
her infrastructure. No routes added up or downstream, no subnetting, and no cabling
considerations. Perhaps most crucial to simplicity, nodes behind ...