NAME
brconfig
- configure network bridge parameters
SYNOPSIS
brconfig
-a
brconfig
bridge
brconfig
bridge
command
[args ...]
DESCRIPTION
The
brconfig
utility is used to configure network bridge parameters and retrieve
network bridge parameters and status from the kernel.
The bridging function is implemented by the
bridge(4)
driver.
A network bridge creates a logical link between two or more
IEEE 802 networks that use the same (or
``similar enough'')
framing format.
For example, it is possible to bridge Ethernet
and 802.11 networks together, but it is not possible to bridge
Ethernet and Token Ring together.
Bridge interfaces are created using the
ifconfig(8)
command's
``create''
sub-command.
All other bridge configuration is performed using
.
The options are as follows:
- -a
-
Display the status of all bridge devices present on the system.
This flag is mutually exclusive with all other sub-commands.
All other operations require that a bridge be specified.
If a bridge is specified with no sub-commands,
the status of that bridge is displayed.
The following sub-commands are available:
- up
-
Start forwarding packets on the bridge.
- down
-
Stop forwarding packets on the bridge.
- add interface
-
Add the interface named by
interface
as a member of the bridge.
The interface is put into promiscuous mode
so that it can receive every packet sent on the network.
- delete interface
-
Remove the interface named by
interface
from the bridge.
Promiscuous mode is disabled on the interface when
it is removed from the bridge.
- maxaddr size
-
Set the size of the bridge address cache to
size.
The default is 100 entries.
- timeout seconds
-
Set the timeout of address cache entries to
seconds
seconds.
If
seconds
is zero, then address cache entries will not be expired.
The default is 1200 seconds.
- deladdr address
-
Delete
address
from the address cache.
- flush
-
Delete all dynamically-learned addresses from the address cache.
- flushall
-
Delete all addresses, including static addresses, from the address cache.
- discover interface
-
Mark an interface as a
``discovering''
interface.
When the bridge has no address cache entry
(either dynamic or static)
for the destination address of a packet,
the bridge will forward the packet to all
member interfaces marked as
``discovering''.
This is the default for all interfaces added to a bridge.
- -discover interface
-
Clear the
``discovering''
attribute on a member interface.
For packets without the
``discovering''
attribute, the only packets forwarded on the interface are broadcast
or multicast packets and packets for which the destination address
is known to be on the interface's segment.
- ipf
-
Enable packet filtering with
pfil(9)
on the bridge.
The current implementation passes
all ARP and RARP packets through the bridge
while filtering IP and IPv6 packets through the configured packet
filter, such as
ipf(4)
or
pf(4).
Other packet types are blocked.
- learn interface
-
Mark an interface as a
``learning''
interface.
When a packet arrives on such an interface, the source
address of the packet is entered into the address cache as being a
destination address on the interface's segment.
This is the default for all interfaces added to a bridge.
- -learn interface
-
Clear the
``learning''
attribute on a member interface.
- stp interface
-
Enable Spanning Tree protocol on
interface.
The
bridge(4)
driver has support for the IEEE 802.1D Spanning Tree protocol (STP).
Spanning Tree is used to detect and remove loops in a network topology.
- -stp interface
-
Disable Spanning Tree protocol on
interface.
This is the default for all interfaces added to a bridge.
- maxage seconds
-
Set the time that a Spanning Tree protocol configuration is valid.
The default is 20 seconds.
The minimum is 1 second and the maximum is 255 seconds.
- fwddelay seconds
-
Set the time that must pass before an interface begins forwarding
packets when Spanning Tree is enabled.
The default is 15 seconds.
The minimum is 1 second and the maximum is 255 seconds.
- hellotime seconds
-
Set the time between broadcasting of Spanning Tree protocol
configuration messages.
The default is 2 seconds.
The minimum is 1 second and the maximum is 255 seconds.
- priority value
-
Set the bridge priority for Spanning Tree.
The default is 32768.
Allowed numerical values range from 0 (highest priority) to 65535
(lowest priority).
- ifpriority interface value
-
Set the Spanning Tree priority of
interface
to
value.
The default is 128.
The minimum is 0 and the maximum is 255.
- ifpathcost interface value
-
Set the Spanning Tree path cost of
interface
to
value.
The default is 55.
The minimum is 0 and the maximum is 65535.
EXAMPLES
The following, when placed in the file
/etc/ifconfig.bridge0
,
will cause a bridge called
`bridge0'
to be created, add the interfaces
`ray0'
and
`fxp0'
to the bridge, and then enable packet forwarding.
Such a configuration could be used to implement a simple
802.11-to-Ethernet bridge (assuming the 802.11 interface is
in ad-hoc mode).
-
create
!brconfig $int add ray0 add fxp0 up
Consider a system with two 4-port Ethernet boards.
The following placed in the file
/etc/ifconfig.bridge0
will cause a bridge consisting of all 8 ports with Spanning Tree
enabled to be created:
-
create
!brconfig $int \
add tlp0 stp tlp0 \
add tlp1 stp tlp1 \
add tlp2 stp tlp2 \
add tlp3 stp tlp3 \
add tlp4 stp tlp4 \
add tlp5 stp tlp5 \
add tlp6 stp tlp6 \
add tlp7 stp tlp7 \
up
SEE ALSO
bridge(4),
pf(4),
ifconfig.if(5),
ifconfig(8),
ipf(8),
pfil(9)
HISTORY
The
brconfig
utility first appeared in
NetBSD1.6.
AUTHORS
The
bridge(4)
driver and
brconfig
utility were originally written by
Jason L. Wright
<jason@thought.net>
as part of an undergraduate independent study at the
University of North Carolina at Greensboro.
This version of the
brconfig
utility was written from scratch by
Jason R. Thorpe
<thorpej@wasabisystems.com>.