This read-write enumerated INTEGER sets the bridging method (transparent, source-route, source-route-transparent, or none) applied to frames at this port, noting Ethernet and FDDI ports support transparent, srt, or none, Token Ring ports support all four, and the UART only supports none. An admin configures this to match the bridging behavior appropriate to the port's media type and the network's bridging topology. Setting sprotoBridge to srt(3) on a Token Ring port allows it to interoperate with both source-routed Token Ring devices and transparently bridged segments.