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Add a section about RSTP support.

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This commit is contained in:
Andrew Thompson 2007-01-20 02:39:34 +00:00
parent 1113949379
commit ab86b1c667
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=166119
1 changed files with 33 additions and 17 deletions
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50
share/man/man4/if_bridge.4
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@ -35,7 +35,7 @@
.\"
.\" $FreeBSD$
.\"
.Dd October 8, 2006
.Dd January 20, 2007
.Dt IF_BRIDGE 4
.Os
.Sh NAME
@ -95,17 +95,6 @@ interfaces that are part of the bridge.
For unicast traffic, the bridge learns which MAC addresses are associated
with which interfaces and will forward the traffic selectively.
.Pp
The
.Nm
driver implements the IEEE 802.1D Spanning Tree protocol (STP).
Spanning Tree is used to detect and remove loops in a network topology.
The bridge can log STP port changes to
.Xr syslog 3
by enabling the
.Va net.link.bridge.log_stp
variable using
.Xr sysctl 8 .
.Pp
All the bridged member interfaces need to be up in order to pass network traffic.
These can be enabled using
.Xr ifconfig 8
@ -130,6 +119,32 @@ This can be used to multiplex the input of two or more interfaces into a single
stream.
This is useful for reconstructing the traffic for network taps
that transmit the RX/TX signals out through two separate interfaces.
.Sh SPANNING TREE
The
.Nm
driver implements the Rapid Spanning Tree Protocol (RSTP or 802.1w) with
backwards compatibility with the legacy Spanning Tree Protocol (STP).
Spanning Tree is used to detect and remove loops in a network topology.
.Pp
RSTP provides faster spanning tree convergence than legacy STP, the protocol
will exchange information with neighbouring switches to quickly transition to
forwarding without creating loops.
.Pp
The code will default to RSTP mode but will downgrade any port connected to a
legacy STP network so is fully backward compatible.
A bridge can be forced to operate in STP mode without rapid state transitions
via the
.Va proto
command in
.Xr ifconfig 8 .
.Pp
The bridge can log STP port changes to
.Xr syslog 3
by enabling the
.Va net.link.bridge.log_stp
variable using
.Xr sysctl 8 .
.Pp
.Sh PACKET FILTERING
Packet filtering can be used with any firewall package that hooks in via the
.Xr pfil 9
@ -234,8 +249,8 @@ ifconfig_fxp0="up"
.Ed
.Pp
Consider a system with two 4-port Ethernet boards.
The following will cause a bridge consisting of all 8 ports with Spanning Tree
enabled to be created:
The following will cause a bridge consisting of all 8 ports with Rapid Spanning
Tree enabled to be created:
.Bd -literal -offset indent
ifconfig bridge0 create
ifconfig bridge0 \e
@ -302,6 +317,10 @@ This version of the
driver has been heavily modified from the original version by
.An Jason R. Thorpe
.Aq thorpej@wasabisystems.com .
.Pp
Rapid Spanning Tree Protocol (RSTP) support was added by
.An Andrew Thompson
.Aq thompsa@FreeBSD.org .
.Sh BUGS
The
.Nm
@ -310,6 +329,3 @@ network devices, with exactly the same interface MTU size as the bridge device.
.Pp
Only wireless interfaces in hostap mode can be bridged due to the 802.11
framing format, bridging a wireless client is not supported yet.
.Pp
The bridge implements version IEEE 802.1D 1998 of the Spanning Tree Protocol so
newer features in IEEE 802.1D 2004 such as RSTP are not available.