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

76 lines
1.6 KiB
Groff
Raw Normal View History

1998-12-21 22:37:53 +00:00
.\"
1999-08-28 00:22:10 +00:00
.\" $FreeBSD$
1998-12-21 22:37:53 +00:00
.\"
.Dd September 28, 1998
1998-12-21 22:37:53 +00:00
.Dt BRIDGE 4
.Os
.Sh NAME
.Nm bridge
.Nd Bridging support
.Sh DESCRIPTION
2000-11-14 11:20:58 +00:00
Starting from version 2.2.8,
.Fx
supports bridging on ethernet-type
interfaces.
This is achieved using the following option
1998-12-21 22:37:53 +00:00
.Bd -literal
options BRIDGE
.Ed
2000-11-14 11:20:58 +00:00
.Pp
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
2000-11-14 11:20:58 +00:00
.Pp
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
2000-11-14 11:20:58 +00:00
.Pp
1998-12-21 22:37:53 +00:00
Set to 1 to enable
.Nm ipfw
filtering on bridged packets.
Note that
1998-12-21 22:37:53 +00:00
.Nm ipfw
rules only apply
to IP packets.
Non-IP packets are subject to the default
1998-12-21 22:37:53 +00:00
.Nm ipfw
rule
.Pq number 65535
which must be an
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
some interfaces when a loop is detected.
No support for a daemon running the
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
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.
1998-12-21 22:37:53 +00:00
.Sh SEE ALSO
.Xr ip 4 ,
.Xr ng_bridge 4 ,
1998-12-21 22:37:53 +00:00
.Xr ipfw 8 ,
.Xr sysctl 8
1998-12-21 22:37:53 +00:00
.Sh HISTORY
.Nm
2000-11-14 11:20:58 +00:00
bridging was introduced in
.Fx 2.2.8
by
.An Luigi Rizzo Aq luigi@iet.unipi.it .