freebsd-dev/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 enabled by including the following line in the kernel configuration
file:
.Pp
.Dl "options BRIDGE"
.Pp
Runtime operation of the bridge is controlled by several
.Xr sysctl 8
variables.
The
.Va net.link.ether.bridge
variable can be set to 
.Li 1
to enable bridging, or set to
.Li 0
to disable it.
.Pp
The
.Va net.link.ether.bridge_ipfw
.Xr sysctl 8
variable can be set to
.Li 1
to enable
.Xr ipfw 8
filtering on bridged packets.
Note that
.Xr ipfw 8
rules only apply
to IP packets.
Non-IP packets are subject to the default
.Xr ipfw 8
rule
.Pq number 65535
which must be an
.Ar allow
rule if ARP and other non-IP packets need to flow through the
bridge.
.Pp
The bridge configuration is controlled by the
.Va net.link.ether.bridge_cfg
.Xr sysctl 8
variable.
It consists of a comma-separated list of
.Ar interface : Ns Ar cluster
pairs, where all interfaces with the same
.Ar cluster 
number will
be bridged together.
.Pp
Another
.Xr sysctl 8
variable reinitializes the bridge; this is required if bridged
configurations include loadable interfaces.
After loading new interface drivers, setting the
.Va net.link.ether.bridge_refresh
variable to
.Li 1
will cause the bridge to reinitialize itself.
.Sh EXAMPLES
The following command will cause the
.Li ep0
and
.Li fxp0
interfaces to be bridged together, and the
.Li fxp1
and
.Li de0 
interfaces to be bridged together:
.Pp
.Dl "sysctl -w net.link.ether.bridge_cfg ep0:0,fxp0:0,fxp1:1,de0:1"
.Sh BUGS
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`
mdoc(7) police: normalize .Nd. 2001-04-18 15:54:10 +00:00			`.Nd bridging support`
Add manpages for dummynet and bridging 1998-12-21 22:37:53 +00:00			`.Sh DESCRIPTION`
Use Fx macro wherever possible. 2000-11-14 11:20:58 +00:00			`Starting from version 2.2.8,`
			`.Fx`
Finally document the net.link.ether.bridge_cfg and net.link.ether.bridge_refresh variables. While I'm here, try to make some of the markup on this page more consistent with the new (markup-reviewed) content. PR: 22060 Reviewed by: ru (for markup, on an earlier version of this delta) MFC after: 2 days 2001-07-26 21:19:25 +00:00			`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.`
Finally document the net.link.ether.bridge_cfg and net.link.ether.bridge_refresh variables. While I'm here, try to make some of the markup on this page more consistent with the new (markup-reviewed) content. PR: 22060 Reviewed by: ru (for markup, on an earlier version of this delta) MFC after: 2 days 2001-07-26 21:19:25 +00:00			`This is enabled by including the following line in the kernel configuration`
			`file:`
Use Fx macro wherever possible. 2000-11-14 11:20:58 +00:00			`.Pp`
Finally document the net.link.ether.bridge_cfg and net.link.ether.bridge_refresh variables. While I'm here, try to make some of the markup on this page more consistent with the new (markup-reviewed) content. PR: 22060 Reviewed by: ru (for markup, on an earlier version of this delta) MFC after: 2 days 2001-07-26 21:19:25 +00:00			`.Dl "options BRIDGE"`
Use Fx macro wherever possible. 2000-11-14 11:20:58 +00:00			`.Pp`
Finally document the net.link.ether.bridge_cfg and net.link.ether.bridge_refresh variables. While I'm here, try to make some of the markup on this page more consistent with the new (markup-reviewed) content. PR: 22060 Reviewed by: ru (for markup, on an earlier version of this delta) MFC after: 2 days 2001-07-26 21:19:25 +00:00			`Runtime operation of the bridge is controlled by several`
			`.Xr sysctl 8`
			`variables.`
			`The`
			`.Va net.link.ether.bridge`
			`variable can be set to`
			`.Li 1`
			`to enable bridging, or set to`
			`.Li 0`
			`to disable it.`
Use Fx macro wherever possible. 2000-11-14 11:20:58 +00:00			`.Pp`
Finally document the net.link.ether.bridge_cfg and net.link.ether.bridge_refresh variables. While I'm here, try to make some of the markup on this page more consistent with the new (markup-reviewed) content. PR: 22060 Reviewed by: ru (for markup, on an earlier version of this delta) MFC after: 2 days 2001-07-26 21:19:25 +00:00			`The`
			`.Va net.link.ether.bridge_ipfw`
			`.Xr sysctl 8`
			`variable can be set to`
			`.Li 1`
			`to enable`
			`.Xr ipfw 8`
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`
Finally document the net.link.ether.bridge_cfg and net.link.ether.bridge_refresh variables. While I'm here, try to make some of the markup on this page more consistent with the new (markup-reviewed) content. PR: 22060 Reviewed by: ru (for markup, on an earlier version of this delta) MFC after: 2 days 2001-07-26 21:19:25 +00:00			`.Xr ipfw 8`
Add manpages for dummynet and bridging 1998-12-21 22:37:53 +00:00			`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`
Finally document the net.link.ether.bridge_cfg and net.link.ether.bridge_refresh variables. While I'm here, try to make some of the markup on this page more consistent with the new (markup-reviewed) content. PR: 22060 Reviewed by: ru (for markup, on an earlier version of this delta) MFC after: 2 days 2001-07-26 21:19:25 +00:00			`.Xr ipfw 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			`rule`
			`.Pq number 65535`
			`which must be an`
Add manpages for dummynet and bridging 1998-12-21 22:37:53 +00:00			`.Ar allow`
Finally document the net.link.ether.bridge_cfg and net.link.ether.bridge_refresh variables. While I'm here, try to make some of the markup on this page more consistent with the new (markup-reviewed) content. PR: 22060 Reviewed by: ru (for markup, on an earlier version of this delta) MFC after: 2 days 2001-07-26 21:19:25 +00:00			`rule if ARP and other non-IP packets need to flow through the`
Add manpages for dummynet and bridging 1998-12-21 22:37:53 +00:00			`bridge.`
Finally document the net.link.ether.bridge_cfg and net.link.ether.bridge_refresh variables. While I'm here, try to make some of the markup on this page more consistent with the new (markup-reviewed) content. PR: 22060 Reviewed by: ru (for markup, on an earlier version of this delta) MFC after: 2 days 2001-07-26 21:19:25 +00:00			`.Pp`
			`The bridge configuration is controlled by the`
			`.Va net.link.ether.bridge_cfg`
			`.Xr sysctl 8`
			`variable.`
			`It consists of a comma-separated list of`
			`.Ar interface : Ns Ar cluster`
			`pairs, where all interfaces with the same`
			`.Ar cluster`
			`number will`
			`be bridged together.`
			`.Pp`
			`Another`
			`.Xr sysctl 8`
			`variable reinitializes the bridge; this is required if bridged`
			`configurations include loadable interfaces.`
			`After loading new interface drivers, setting the`
			`.Va net.link.ether.bridge_refresh`
			`variable to`
			`.Li 1`
			`will cause the bridge to reinitialize itself.`
			`.Sh EXAMPLES`
			`The following command will cause the`
			`.Li ep0`
			`and`
			`.Li fxp0`
			`interfaces to be bridged together, and the`
			`.Li fxp1`
			`and`
			`.Li de0`
			`interfaces to be bridged together:`
			`.Pp`
			`.Dl "sysctl -w net.link.ether.bridge_cfg ep0:0,fxp0:0,fxp1:1,de0:1"`
Add manpages for dummynet and bridging 1998-12-21 22:37:53 +00:00			`.Sh BUGS`
			`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 .`