BRIDGE(3) BRIDGE(3)
NAME
bridge - IP Ethernet bridge
SYNOPSIS
bind -a #Bb /net
/net/bridgeb/ctl
/net/bridgeb/cache
/net/bridgeb/log
/net/bridgeb/stats
/net/bridgeb/n
/net/bridgeb/n/ctl
/net/bridgeb/n/local
/net/bridgeb/n/status
DESCRIPTION
The bridge device bridges packets amongst Ethernet inter-
faces. The number b in the bind is optional and selects a
particular bridge (default 0).
The /net/bridge0 directory contains ctl, cache, log, and
stats files, and numbered subdirectories for each physical
interface.
Opening the ctl file reserves an interface. The file
descriptor returned from the open(2) will point to the con-
trol file, ctl, of the newly allocated interface. Reading
ctl returns a text string representing the number of the
interface. Writing ctl alters aspects of the interface.
The possible ctl messages are:
bind ether name ownhash path [pvid[#prio][,vlans...]]
Treat the device mounted at path (e.g., `/net/ether0')
as an Ethernet medium and associate it with this bridge
(forward its packets to the other interfaces associated
with this bridge). Ownhash is an `owner hash'. The
optional [pvid[#prio][,vlans...]] argument is explained
in vlan command below.
bind bypass name ownhash path [pvid[#prio][,vlans...]]
This is the same as ether above, but bypasses the phys-
ical interface, ignoring all received frames from the
interface and diverts all frames transmitted on that
interface to the bridge.
bind tunnel name ownhash path path2 [pvid[#prio][,vlans...]]
Treat the device mounted at path as a network tunnel
carrying Ethernet packets, the device mounted at path2
as an Ethernet and associate them with this bridge
(forward its packets to the other interfaces associated
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BRIDGE(3) BRIDGE(3)
with this bridge). Read packets from the path inter-
face and write them to the path2 interface. Such tun-
nels have an MTU of 1400 bytes.
vlan pvid[#prio][,vlans...] type name [ownhash]
Change the 802.1Q VLAN configuration of a port identi-
fied by type, name and ownhash. The pvid is the
"Native" VLAN id associated with untagged packets on a
port. Packets with a VLAN id of pvid will be send out
untagged on the port. Untagged packets received on the
port will be tagged with the pvid. When pvid was not
specified in a bind command above, ports default to a
pvid of 1. The pvid can be specified as 0 when
untagged packets should be ignored on a port. The
optional prio argument specifies the default priority
to assign to a incoming untagged packet on the port
between 0 (lowest, default) and 7 (highest). The
vlans... argument specifies comma separated ranges of
other VLAN id's that the port is a member of (for trunk
ports). Membership means the port is accepting tagged
packets with VLAN id's listed here and ignores VLAN
id's not listed here. Once accepted, packets are for-
warded only to other ports that are members of the same
(accepted) VLAN id. Unless pvid is 0, a port is always
a member of its own pvid VLAN id, so it does not need
to be listed twice.
unbind type name [ownhash]
Disassociate the interface associated with name from
this bridge. Type must be `ether' or `tunnel'.
cacheflush
Clear the cache of (destination MAC address, VLAN id,
port) tuples.
delay delay0 delayn
Set the delay0 and delayn parameters. delay0 is the
constant microsecond delay per packet and delayn is the
microsecond delay per byte.
set option
Set bridge option. The only known option is `tcpmss',
which limits the TCP Maximum Segment Size of TCP pack-
ets passing through to 1300 bytes.
clear option
Clear bridge option.
Reading stats returns statistics about the bridge.
Reading the log file returns data from the bridge's log and
will block at end of file awaiting new data.
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Reading the cache file prints the cache of (destination MAC
address, VLAN id, port) tuples, one entry per line. The
format is: the destination MAC (e.g., Ethernet) address in
hex, VLAN id, port number, count of packets from this
address, count of packets to this address, expiry time in
seconds since the epoch, and `e' for expired entries or `v'
for valid entries.
In a connection subdirectory, ctl and local don't do any-
thing, but status returns a one-line status summary.
EXAMPLES
Set up a network bridge between two Ethernets (`#l0' and
`#l1').
bind -a '#B' /net
bind -a '#l1' /net
echo 'bind ether outer 0 /net/ether0' >/net/bridge0/ctl
echo 'bind ether inner 0 /net/ether1' >/net/bridge0/ctl
Set up bridge1 with 3 access ports and a trunk port.
# create bridge1
bind -a '#B1' /net
# nic for trunk carrying only tagged vlans 10,20 and 30
bind -a '#l0' /net
echo 'bind ether trunk 0 /net/ether0 0,10,20,30' >/net/bridge1/ctl
# create virtual nics for access ports
bind -a '#l1:sink ea=001122334401' /net
bind -a '#l2:sink ea=001122334402' /net
bind -a '#l3:sink ea=001122334403' /net
echo 'bind ether port1 0 /net/ether1 10' >/net/bridge1/ctl
echo 'bind ether port2 0 /net/ether2 20' >/net/bridge1/ctl
echo 'bind ether port3 0 /net/ether3 30' >/net/bridge1/ctl
SEE ALSO
ip(3), ether(3)
SOURCE
/sys/src/9/port/devbridge.c
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