BRIDGE(8) Linux BRIDGE(8)
NAME
bridge - show / manipulate bridge addresses and devices
SYNOPSIS
bridge [ OPTIONS ] OBJECT { COMMAND | help }
OBJECT := { link | fdb | mdb | vlan | monitor }
OPTIONS := { -V[ersion] | -s[tatistics] | -n[etns] name }
bridge link set dev DEV [ cost COST ] [ priority PRIO ] [ state STATE] [ guard { on | off } ] [ hairpin { on
| off } ] [ fastleave { on | off } ] [ root_block { on | off } ] [ hwmode { vepa | veb } ]
bridge link [ show ] [ dev DEV ]
bridge fdb { add | append | del } LLADDR dev DEV { local | temp } [ self ] [ master ] [ router ] [ use ] [ dst
IPADDR ] [ vni VNI ] [ port PORT ] [ via DEVICE ]
bridge fdb [ show ] [ dev DEV ]
bridge mdb { add | del } dev DEV port PORT grp GROUP [ permanent | temp ]
bridge mdb show [ dev DEV ]
bridge vlan { add | del } dev DEV vid VID [ pvid ] [ untagged ] [ self ] [ master ]
bridge vlan [ show ] [ dev DEV ]
bridge monitor [ all | neigh | link | mdb ]
OPTIONS
-V, -Version
print the version of the bridge utility and exit.
-s, -stats, -statistics
output more information. If this option is given multiple times, the amount of information increases.
As a rule, the information is statistics or some time values.
-n, -net, -netns <NETNS>
switches bridge to the specified network namespace NETNS. Actually it just simplifies executing of:
ip netns exec NETNS bridge [ OPTIONS ] OBJECT { COMMAND | help }
to
bridge -n[etns] NETNS [ OPTIONS ] OBJECT { COMMAND | help }
BRIDGE - COMMAND SYNTAX
OBJECT
COMMAND
Specifies the action to perform on the object. The set of possible actions depends on the object type. As a
rule, it is possible to add, delete and show (or list ) objects, but some objects do not allow all of these
operations or have some additional commands. The help command is available for all objects. It prints out a
list of available commands and argument syntax conventions.
If no command is given, some default command is assumed. Usually it is list or, if the objects of this class
cannot be listed, help.
bridge link - bridge port
link objects correspond to the port devices of the bridge.
The corresponding commands set and display port status and bridge specific attributes.
bridge link set - set bridge specific attributes on a port
dev NAME
interface name of the bridge port
cost COST
the STP path cost of the specified port.
priority PRIO
the STP port priority. The priority value is an unsigned 8-bit quantity (number between 0 and 255).
This metric is used in the designated port an droot port selectio algorithms.
state STATE
the operation state of the port. This is primarily used by user space STP/RSTP implementation. The fol‐
lowing is a list of valid values:
0 - port is DISABLED. Make this port completely inactive.
1 - STP LISTENING state. Only valid if STP is enabled on the brige. In this state the port for list for
STP BPDUs and drop all other traffic.
2 - STP LEARNING state. Only valid if STP is enabled on the bridge. In this state the port will accept
traffic only for the purpose of updating MAC address tables.
3 - STP FORWARDING state. Port is fully active.
4 - STP BLOCKING state. Only valid if STP is enabled on the bridge. This state is used during the STP
election process. In this state, port will only process STP BPDUs.
message. It is only used with IGMP snooping is enabled on the bridge. By default the flag is off.
root_block on or root_block off
Controls whether a given port is allowed to become root port or not. Only used when STP is enabled on
the bridge. By default the flag is off.
hwmode Some network interface cards support HW bridge functionality and they may be configured in different
modes. Currently support modes are:
vepa - Data sent between HW ports is sent on the wire to the external switch.
veb - bridging happens in hardware.
bridge link show - list bridge port configuration.
This command displays the current bridge port configuration and flags.
bridge fdb - forwarding database management
fdb objects contain known Ethernet addresses on a link.
The corresponding commands display fdb entries, add new entries, append entries, and delete old ones.
bridge fdb add - add a new fdb entry
This command creates a new fdb entry.
LLADDR the Ethernet MAC address.
dev DEV
the interface to which this address is associated.
self - the address is associated with the port drivers fdb. Usually hardware.
master - the address is associated with master devices fdb. Usually software (default).
router - the destination address is associated with a router. Valid if the referenced device is a
VXLAN type device and has route shortcircuit enabled.
use - the address is in use. User space can use this option to indicate to the kernel that the fdb
entry is in use.
The next command line parameters apply only when the specified device DEV is of type VXLAN.
dst IPADDR
via DEVICE
device name of the outgoing interface for the VXLAN device driver to reach the remote VXLAN tunnel end‐
point.
bridge fdb append - append a forwarding database entry
This command adds a new fdb entry with an already known LLADDR. Valid only for multicast link layer
addresses. The command adds support for broadcast and multicast Ethernet MAC addresses. The Ethernet MAC
address is added multiple times into the forwarding database and the vxlan device driver sends a copy of the
data packet to each entry found.
The arguments are the same as with bridge fdb add,
bridge fdb delete - delete a forwarding database entry
This command removes an existing fdb entry.
The arguments are the same as with bridge fdb add,
bridge fdb show - list forwarding entries.
This command displays the current forwarding table.
With the -statistics option, the command becomes verbose. It prints out the last updated and last used time
for each entry.
bridge mdb - multicast group database management
mdb objects contain known IP multicast group addresses on a link.
The corresponding commands display mdb entries, add new entries, and delete old ones.
bridge mdb add - add a new multicast group database entry
This command creates a new mdb entry.
dev DEV
the interface where this group address is associated.
port PORT
the port whose link is known to have members of this multicast group.
grp GROUP
the IP multicast group address whose members reside on the link connected to the port.
permanent - the mdb entry is permanent
bridge mdb show - list multicast group database entries
This command displays the current multicast group membership table. The table is populated by IGMP and MLD
snooping in the bridge driver automatically. It can be altered by bridge mdb add and bridge mdb del commands
manually too.
dev DEV
the interface only whose entries should be listed. Default is to list all bridge interfaces.
With the -details option, the command becomes verbose. It prints out the ports known to have a connected
router.
bridge vlan - VLAN filter list
vlan objects contain known VLAN IDs for a link.
The corresponding commands display vlan filter entries, add new entries, and delete old ones.
bridge vlan add - add a new vlan filter entry
This command creates a new vlan filter entry.
dev NAME
the interface with which this vlan is associated.
vid VID
the VLAN ID that identifies the vlan.
pvid the vlan specified is to be considered a PVID at ingress. Any untagged frames will be assigned to this
VLAN.
untagged
the vlan specified is to be treated as untagged on egress.
self the vlan is configured on the specified physical device. Required if the device is the bridge device.
master the vlan is configured on the software bridge (default).
bridge vlan delete - delete a forwarding database entry
This command removes an existing fdb entry.
The arguments are the same as with bridge vlan add. The pvid and untagged flags are ignored.
OBJECT-LIST is the list of object types that we want to monitor. It may contain link, fdb, and mdb. If no
file argument is given, bridge opens RTNETLINK, listens on it and dumps state changes in the format described
in previous sections.
If a file name is given, it does not listen on RTNETLINK, but opens the file containing RTNETLINK messages
saved in binary format and dumps them.
NOTES
This command uses facilities added in Linux 3.0.
Although the forwarding table is maintained on a per-bridge device basis the bridge device is not part of the
syntax. This is a limitation of the underlying netlink neighbour message protocol. When displaying the for‐
warding table, entries for all bridges are displayed. Add/delete/modify commands determine the underlying
bridge device based on the bridge to which the corresponding ethernet device is attached.
SEE ALSO
ip(8)
BUGS
Please direct bugreports and patches to: <[email protected]>
AUTHOR
Original Manpage by Stephen Hemminger
iproute2 1 August 2012 BRIDGE(8)
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