.\" .\" $Id: bridge.4,v 1.2 1998/12/21 22:37:53 luigi Exp $ .\" .Dd Sep 28, 1998 .Dt BRIDGE 4 .Os .Sh NAME .Nm bridge .Nd Bridging support .Sh DESCRIPTION Starting from version 2.2.8, FreeBSD supports bridging on ethernet-type interfaces. This is achieved using the following option .Bd -literal options BRIDGE .Ed in the kernel config file, and is controlled by two .Nm sysctl variables: .Bd -literal net.link.ether.bridge .Ed Set to 1 to enable bridging, set to 0 to disable it .Bd -literal net.link.ether.bridge_ipfw .Ed Set to 1 to enable .Nm ipfw filtering on bridged packets. Note that .Nm ipfw rules only apply to IP packets. Non-IP packets are subject to the default .Nm ipfw rule (number 65535) which must be an .Ar allow rule if we want ARP and other non-IP packets to flow through the bridge. .Sh BUGS .Pp Care must be taken not to construct loops in the bridge topology. The kernel supports only a primitive form of loop detection, by disabling some interfaces when a loop is detected. No support for a daemon running the spanning tree algorithm is currently provided. .Pp With bridging active, interfaces are in promiscuous mode, thus causing some load on the system to receive and filter out undesired traffic. .Pp Extended functionality to enable bridging selectively on clusters of interfaces is still in the works. .Pp Not all interface support bridging -- at the moment it works for ``ed'', ``de'', ``ep'', ``fxp'', ``lnc'', ``fe'' interfaces. .Sh SEE ALSO .Xr ip 4 , .Xr ipfw 8 , .Xr sysctl 8 . .Sh HISTORY .Nm bridging has been introduced in FreeBSD 2.2.8 by Luigi Rizzo .