freebsd-skq/share/man/man4/bridge.4

.\"
.\" $FreeBSD$
.\"
.Dd September 28, 1998
.Dt BRIDGE 4
.Os
.Sh NAME
.Nm bridge
.Nd Bridging support
.Sh DESCRIPTION
Starting from version 2.2.8,
.Fx
supports bridging on ethernet-type
interfaces.
This is achieved using the following option
.Bd -literal
    options BRIDGE
.Ed
.Pp
in the kernel config file, and is controlled by two
.Nm sysctl
variables:
.Bd -literal
    net.link.ether.bridge
.Ed
.Pp
Set to 1 to enable bridging, set to 0 to disable it
.Bd -literal
    net.link.ether.bridge_ipfw
.Ed
.Pp
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
.Pq 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
Interfaces that cannot be put into promiscuous mode or that don't
support sending packets with arbitrary Ethernet source addresses
are not compatible with bridging.
.Sh SEE ALSO
.Xr ip 4 ,
.Xr ng_bridge 4 ,
.Xr ipfw 8 ,
.Xr sysctl 8
.Sh HISTORY
.Nm
bridging was introduced in
.Fx 2.2.8
by
.An Luigi Rizzo Aq luigi@iet.unipi.it .
Add manpages for dummynet and bridging 1998-12-21 22:37:53 +00:00			`.\"`
$Id$ -> $FreeBSD$ 1999-08-28 00:22:10 +00:00			`.\" $FreeBSD$`
Add manpages for dummynet and bridging 1998-12-21 22:37:53 +00:00			`.\"`
mdoc(7) police: use canonical form of .Dd macro. 2000-12-11 15:47:53 +00:00			`.Dd September 28, 1998`
Add manpages for dummynet and bridging 1998-12-21 22:37:53 +00:00			`.Dt BRIDGE 4`
			`.Os`
			`.Sh NAME`
			`.Nm bridge`
			`.Nd Bridging support`
			`.Sh DESCRIPTION`
Use Fx macro wherever possible. 2000-11-14 11:20:58 +00:00			`Starting from version 2.2.8,`
			`.Fx`
			`supports bridging on ethernet-type`
Remove single-space hard sentence breaks. These degrade the quality of the typeset output, tend to make diffs harder to read and provide bad examples for new-comers to mdoc. 2000-03-01 14:50:24 +00:00			`interfaces.`
			`This is achieved using the following option`
Add manpages for dummynet and bridging 1998-12-21 22:37:53 +00:00			`.Bd -literal`
			`options BRIDGE`
			`.Ed`
Use Fx macro wherever possible. 2000-11-14 11:20:58 +00:00			`.Pp`
Add manpages for dummynet and bridging 1998-12-21 22:37:53 +00:00			`in the kernel config file, and is controlled by two`
			`.Nm sysctl`
			`variables:`
			`.Bd -literal`
			`net.link.ether.bridge`
			`.Ed`
Use Fx macro wherever possible. 2000-11-14 11:20:58 +00:00			`.Pp`
Add manpages for dummynet and bridging 1998-12-21 22:37:53 +00:00			`Set to 1 to enable bridging, set to 0 to disable it`
			`.Bd -literal`
			`net.link.ether.bridge_ipfw`
			`.Ed`
Use Fx macro wherever possible. 2000-11-14 11:20:58 +00:00			`.Pp`
Add manpages for dummynet and bridging 1998-12-21 22:37:53 +00:00			`Set to 1 to enable`
			`.Nm ipfw`
Remove single-space hard sentence breaks. These degrade the quality of the typeset output, tend to make diffs harder to read and provide bad examples for new-comers to mdoc. 2000-03-01 14:50:24 +00:00			`filtering on bridged packets.`
			`Note that`
Add manpages for dummynet and bridging 1998-12-21 22:37:53 +00:00			`.Nm ipfw`
			`rules only apply`
Remove single-space hard sentence breaks. These degrade the quality of the typeset output, tend to make diffs harder to read and provide bad examples for new-comers to mdoc. 2000-03-01 14:50:24 +00:00			`to IP packets.`
			`Non-IP packets are subject to the default`
Add manpages for dummynet and bridging 1998-12-21 22:37:53 +00:00			`.Nm ipfw`
Revise list of interfaces on which bridging is supported. mdoc-ify a few things while I'm here. 1999-04-16 02:09:38 +00:00			`rule`
			`.Pq number 65535`
			`which must be an`
Add manpages for dummynet and bridging 1998-12-21 22:37:53 +00:00			`.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`
Remove single-space hard sentence breaks. These degrade the quality of the typeset output, tend to make diffs harder to read and provide bad examples for new-comers to mdoc. 2000-03-01 14:50:24 +00:00			`some interfaces when a loop is detected.`
			`No support for a daemon running the`
Add manpages for dummynet and bridging 1998-12-21 22:37:53 +00:00			`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`
Now almost all Ethernet drivers support bridging. Noticed by: gallatin 2000-11-10 16:58:13 +00:00			`Interfaces that cannot be put into promiscuous mode or that don't`
			`support sending packets with arbitrary Ethernet source addresses`
			`are not compatible with bridging.`
Add manpages for dummynet and bridging 1998-12-21 22:37:53 +00:00			`.Sh SEE ALSO`
			`.Xr ip 4 ,`
New netgraph node type for Ethernet bridging. 2000-09-01 01:37:25 +00:00			`.Xr ng_bridge 4 ,`
Add manpages for dummynet and bridging 1998-12-21 22:37:53 +00:00			`.Xr ipfw 8 ,`
remove fullstops from the end of .Xr lines in SEE ALSO sections. 2000-11-15 16:00:07 +00:00			`.Xr sysctl 8`
Add manpages for dummynet and bridging 1998-12-21 22:37:53 +00:00			`.Sh HISTORY`
			`.Nm`
Use Fx macro wherever possible. 2000-11-14 11:20:58 +00:00			`bridging was introduced in`
			`.Fx 2.2.8`
Revise list of interfaces on which bridging is supported. mdoc-ify a few things while I'm here. 1999-04-16 02:09:38 +00:00			`by`
			`.An Luigi Rizzo Aq luigi@iet.unipi.it .`