1BRIDGE(8) Linux BRIDGE(8)
2
6 bridge - show / manipulate bridge addresses and devices
7
9 bridge [ OPTIONS ] OBJECT { COMMAND | help }
10 OBJECT := { link | fdb | mdb | vlan | monitor }
13 OPTIONS := { -V[ersion] | -s[tatistics] | -n[etns] name | -b[atch]
16 filename | -c[lor] | -p[retty] | -j[son] | -o[neline] }
17 bridge link set dev DEV [ cost COST ] [ priority PRIO ] [ state STATE ]
19 [ guard { on | off } ] [ hairpin { on | off } ] [ fastleave {
20 on | off } ] [ root_block { on | off } ] [ learning { on | off
21 } ] [ learning_sync { on | off } ] [ flood { on | off } ] [ hw‐
22 mode { vepa | veb } ] [ mcast_flood { on | off } ] [
23 mcast_to_unicast { on | off } ] [ neigh_suppress { on | off } ]
24 [ vlan_tunnel { on | off } ] [ isolated { on | off } ] [
25 backup_port DEVICE ] [ nobackup_port ] [ self ] [ master ]
26 bridge link [ show ] [ dev DEV ]
28 bridge fdb { add | append | del | replace } LLADDR dev DEV { local |
30 static | dynamic } [ self ] [ master ] [ router ] [ use ] [ ex‐
31 tern_learn ] [ sticky ] [ src_vni VNI ] { [ dst IPADDR ] [ vni
32 VNI ] [ port PORT ] [ via DEVICE ] | nhid NHID }
33 bridge fdb [ [ show ] [ br BRDEV ] [ brport DEV ] [ vlan VID ] [ state
35 STATE ] [ dynamic ] ]
36 bridge fdb get [ to ] LLADDR [ br BRDEV ] { brport | dev } DEV [ vlan
38 VID ] [ vni VNI ] [ self ] [ master ] [ dynamic ]
39 bridge mdb { add | del } dev DEV port PORT grp GROUP [ src SOURCE ] [
41 permanent | temp ] [ vid VID ]
42 bridge mdb show [ dev DEV ]
44 bridge vlan { add | del } dev DEV vid VID [ tunnel_info TUNNEL_ID ] [
46 pvid ] [ untagged ] [ self ] [ master ]
47 bridge vlan set dev DEV vid VID [ state STP_STATE ]
49 bridge vlan [ show | tunnelshow ] [ dev DEV ]
51 bridge monitor [ all | neigh | link | mdb | vlan ]
53
56 -V, -Version
57 print the version of the bridge utility and exit.
58 -s, -stats, -statistics
61 output more information. If this option is given multiple times,
62 the amount of information increases. As a rule, the information
63 is statistics or some time values.
64 -d, -details
67 print detailed information about bridge vlan filter entries or
68 MDB router ports.
69 -n, -net, -netns <NETNS>
72 switches bridge to the specified network namespace NETNS. Actu‐
73 ally it just simplifies executing of:
74 ip netns exec NETNS bridge [ OPTIONS ] OBJECT { COMMAND | help }
76 to
78 bridge -n[etns] NETNS [ OPTIONS ] OBJECT { COMMAND | help }
80 -b, -batch <FILENAME>
83 Read commands from provided file or standard input and invoke
84 them. First failure will cause termination of bridge command.
85 -force Don't terminate bridge command on errors in batch mode. If
88 there were any errors during execution of the commands, the ap‐
89 plication return code will be non zero.
90 -c[color][={always|auto|never}
93 Configure color output. If parameter is omitted or always, color
94 output is enabled regardless of stdout state. If parameter is
95 auto, stdout is checked to be a terminal before enabling color
96 output. If parameter is never, color output is disabled. If
97 specified multiple times, the last one takes precedence. This
98 flag is ignored if -json is also given.
99 -j, -json
102 Output results in JavaScript Object Notation (JSON).
103 -p, -pretty
106 When combined with -j generate a pretty JSON output.
107 -o, -oneline
110 output each record on a single line, replacing line feeds with
111 the '\' character. This is convenient when you want to count
112 records with wc(1) or to grep(1) the output.
113
117 OBJECT
118 link - Bridge port.
119 fdb - Forwarding Database entry.
122 mdb - Multicast group database entry.
125 vlan - VLAN filter list.
128 COMMAND
131 Specifies the action to perform on the object. The set of possible ac‐
132 tions depends on the object type. As a rule, it is possible to add,
133 delete and show (or list ) objects, but some objects do not allow all
134 of these operations or have some additional commands. The help command
135 is available for all objects. It prints out a list of available com‐
136 mands and argument syntax conventions.
137 If no command is given, some default command is assumed. Usually it is
139 list or, if the objects of this class cannot be listed, help.
140
143 link objects correspond to the port devices of the bridge.
144 The corresponding commands set and display port status and bridge spe‐
147 cific attributes.
148 bridge link set - set bridge specific attributes on a port
151 dev NAME
152 interface name of the bridge port
153 cost COST
156 the STP path cost of the specified port.
157 priority PRIO
160 the STP port priority. The priority value is an unsigned 8-bit
161 quantity (number between 0 and 255). This metric is used in the
162 designated port an droot port selection algorithms.
163 state STATE
166 the operation state of the port. Except state 0 (disable STP or
167 BPDU filter feature), this is primarily used by user space
168 STP/RSTP implementation. One may enter port state name (case in‐
169 sensitive), or one of the numbers below. Negative inputs are ig‐
170 nored, and unrecognized names return an error.
171 0 - port is in STP DISABLED state. Make this port completely in‐
173 active for STP. This is also called BPDU filter and could be
174 used to disable STP on an untrusted port, like a leaf virtual
175 devices.
176 1 - port is in STP LISTENING state. Only valid if STP is enabled
179 on the bridge. In this state the port listens for STP BPDUs and
180 drops all other traffic frames.
181 2 - port is in STP LEARNING state. Only valid if STP is enabled
184 on the bridge. In this state the port will accept traffic only
185 for the purpose of updating MAC address tables.
186 3 - port is in STP FORWARDING state. Port is fully active.
189 4 - port is in STP BLOCKING state. Only valid if STP is enabled
192 on the bridge. This state is used during the STP election
193 process. In this state, port will only process STP BPDUs.
194 guard on or guard off
198 Controls whether STP BPDUs will be processed by the bridge port.
199 By default, the flag is turned off allowed BPDU processing.
200 Turning this flag on will disables the bridge port if a STP BPDU
201 packet is received.
202 If running Spanning Tree on bridge, hostile devices on the net‐
204 work may send BPDU on a port and cause network failure. Setting
205 guard on will detect and stop this by disabling the port. The
206 port will be restarted if link is brought down, or removed and
207 reattached. For example if guard is enable on eth0:
208 ip link set dev eth0 down; ip link set dev eth0 up
210 hairpin on or hairpin off
213 Controls whether traffic may be send back out of the port on
214 which it was received. This option is also called reflective re‐
215 lay mode, and is used to support basic VEPA (Virtual Ethernet
216 Port Aggregator) capabilities. By default, this flag is turned
217 off and the bridge will not forward traffic back out of the re‐
218 ceiving port.
219 fastleave on or fastleave off
222 This flag allows the bridge to immediately stop multicast traf‐
223 fic on a port that receives IGMP Leave message. It is only used
224 with IGMP snooping is enabled on the bridge. By default the flag
225 is off.
226 root_block on or root_block off
229 Controls whether a given port is allowed to become root port or
230 not. Only used when STP is enabled on the bridge. By default the
231 flag is off.
232 This feature is also called root port guard. If BPDU is re‐
234 ceived from a leaf (edge) port, it should not be elected as root
235 port. This could be used if using STP on a bridge and the down‐
236 stream bridges are not fully trusted; this prevents a hostile
237 guest from rerouting traffic.
238 learning on or learning off
241 Controls whether a given port will learn MAC addresses from re‐
242 ceived traffic or not. If learning if off, the bridge will end
243 up flooding any traffic for which it has no FDB entry. By de‐
244 fault this flag is on.
245 learning_sync on or learning_sync off
248 Controls whether a given port will sync MAC addresses learned on
249 device port to bridge FDB.
250 flood on or flood off
253 Controls whether unicast traffic for which there is no FDB entry
254 will be flooded towards this given port. By default this flag is
255 on.
256 hwmode Some network interface cards support HW bridge functionality and
259 they may be configured in different modes. Currently support
260 modes are:
261 vepa - Data sent between HW ports is sent on the wire to the ex‐
263 ternal switch.
264 veb - bridging happens in hardware.
266 mcast_flood on or mcast_flood off
269 Controls whether multicast traffic for which there is no MDB en‐
270 try will be flooded towards this given port. By default this
271 flag is on.
272 mcast_to_unicast on or mcast_to_unicast off
275 Controls whether a given port will replicate packets using uni‐
276 cast instead of multicast. By default this flag is off.
277 This is done by copying the packet per host and changing the
279 multicast destination MAC to a unicast one accordingly.
280 mcast_to_unicast works on top of the multicast snooping feature
282 of the bridge. Which means unicast copies are only delivered to
283 hosts which are interested in it and signalized this via
284 IGMP/MLD reports previously.
285 This feature is intended for interface types which have a more
287 reliable and/or efficient way to deliver unicast packets than
288 broadcast ones (e.g. WiFi).
289 However, it should only be enabled on interfaces where no
291 IGMPv2/MLDv1 report suppression takes place. IGMP/MLD report
292 suppression issue is usually overcome by the network daemon
293 (supplicant) enabling AP isolation and by that separating all
294 STAs.
295 Delivery of STA-to-STA IP multicast is made possible again by
297 enabling and utilizing the bridge hairpin mode, which considers
298 the incoming port as a potential outgoing port, too (see hairpin
299 option). Hairpin mode is performed after multicast snooping,
300 therefore leading to only deliver reports to STAs running a mul‐
301 ticast router.
302 neigh_suppress on or neigh_suppress off
305 Controls whether neigh discovery (arp and nd) proxy and suppres‐
306 sion is enabled on the port. By default this flag is off.
307 vlan_tunnel on or vlan_tunnel off
310 Controls whether vlan to tunnel mapping is enabled on the port.
311 By default this flag is off.
312 isolated on or isolated off
315 Controls whether a given port will be isolated, which means it
316 will be able to communicate with non-isolated ports only. By
317 default this flag is off.
318 backup_port DEVICE
321 If the port loses carrier all traffic will be redirected to the
322 configured backup port
323 nobackup_port
326 Removes the currently configured backup port
327 self link setting is configured on specified physical device
330 master link setting is configured on the software bridge (default)
333 -t, -timestamp
336 display current time when using monitor option.
337 bridge link show - list ports configuration for all bridges.
340 This command displays port configuration and flags for all bridges.
341 To display port configuration and flags for a specific bridge, use the
343 "ip link show master <bridge_device>" command.
344
347 fdb objects contain known Ethernet addresses on a link.
348 The corresponding commands display fdb entries, add new entries, append
351 entries, and delete old ones.
352 bridge fdb add - add a new fdb entry
355 This command creates a new fdb entry.
356 LLADDR the Ethernet MAC address.
359 dev DEV
362 the interface to which this address is associated.
363 local - is a local permanent fdb entry, which means that the
365 bridge will not forward frames with this destination MAC address
366 and VLAN ID, but terminate them locally. This flag is default
367 unless "static" or "dynamic" are explicitly specified.
368 permanent - this is a synonym for "local"
371 static - is a static (no arp) fdb entry
374 dynamic - is a dynamic reachable age-able fdb entry
377 self - the operation is fulfilled directly by the driver for the
380 specified network device. If the network device belongs to a
381 master like a bridge, then the bridge is bypassed and not noti‐
382 fied of this operation (and if the device does notify the
383 bridge, it is driver-specific behavior and not mandated by this
384 flag, check the driver for more details). The "bridge fdb add"
385 command can also be used on the bridge device itself, and in
386 this case, the added fdb entries will be locally terminated (not
387 forwarded). In the latter case, the "self" flag is mandatory.
388 The flag is set by default if "master" is not specified.
389 master - if the specified network device is a port that belongs
392 to a master device such as a bridge, the operation is fulfilled
393 by the master device's driver, which may in turn notify the port
394 driver too of the address. If the specified device is a master
395 itself, such as a bridge, this flag is invalid.
396 router - the destination address is associated with a router.
399 Valid if the referenced device is a VXLAN type device and has
400 route short circuit enabled.
401 use - the address is in use. User space can use this option to
404 indicate to the kernel that the fdb entry is in use.
405 extern_learn - this entry was learned externally. This option
408 can be used to indicate to the kernel that an entry was hardware
409 or user-space controller learnt dynamic entry. Kernel will not
410 age such an entry.
411 sticky - this entry will not change its port due to learning.
414 The next command line parameters apply only when the specified device
417 DEV is of type VXLAN.
418 dst IPADDR
420 the IP address of the destination VXLAN tunnel endpoint where
421 the Ethernet MAC ADDRESS resides.
422 src_vni VNI
425 the src VNI Network Identifier (or VXLAN Segment ID) this entry
426 belongs to. Used only when the vxlan device is in external or
427 collect metadata mode. If omitted the value specified at vxlan
428 device creation will be used.
429 vni VNI
432 the VXLAN VNI Network Identifier (or VXLAN Segment ID) to use to
433 connect to the remote VXLAN tunnel endpoint. If omitted the
434 value specified at vxlan device creation will be used.
435 port PORT
438 the UDP destination PORT number to use to connect to the remote
439 VXLAN tunnel endpoint. If omitted the default value is used.
440 via DEVICE
443 device name of the outgoing interface for the VXLAN device
444 driver to reach the remote VXLAN tunnel endpoint.
445 nhid NHID
448 ecmp nexthop group for the VXLAN device driver to reach remote
449 VXLAN tunnel endpoints.
450 bridge fdb append - append a forwarding database entry
453 This command adds a new fdb entry with an already known LLADDR. Valid
454 only for multicast link layer addresses. The command adds support for
455 broadcast and multicast Ethernet MAC addresses. The Ethernet MAC ad‐
456 dress is added multiple times into the forwarding database and the
457 vxlan device driver sends a copy of the data packet to each entry
458 found.
459 The arguments are the same as with bridge fdb add.
462 bridge fdb delete - delete a forwarding database entry
465 This command removes an existing fdb entry.
466 The arguments are the same as with bridge fdb add.
469 bridge fdb replace - replace a forwarding database entry
472 If no matching entry is found, a new one will be created instead.
473 The arguments are the same as with bridge fdb add.
476 bridge fdb show - list forwarding entries.
479 This command displays the current forwarding table.
480 With the -statistics option, the command becomes verbose. It prints out
483 the last updated and last used time for each entry.
484 bridge fdb get - get bridge forwarding entry.
487 lookup a bridge forwarding table entry.
488 LLADDR the Ethernet MAC address.
491 dev DEV
494 the interface to which this address is associated.
495 brport DEV
498 the bridge port to which this address is associated. same as dev
499 above.
500 br DEV the bridge to which this address is associated.
503 self - the address is associated with the port drivers fdb. Usually
506 hardware.
507 master - the address is associated with master devices fdb. Usually
510 software (default).
511
515 mdb objects contain known IP or L2 multicast group addresses on a link.
516 The corresponding commands display mdb entries, add new entries, and
519 delete old ones.
520 bridge mdb add - add a new multicast group database entry
523 This command creates a new mdb entry.
524 dev DEV
527 the interface where this group address is associated.
528 port PORT
531 the port whose link is known to have members of this multicast
532 group.
533 grp GROUP
536 the multicast group address (IPv4, IPv6 or L2 multicast) whose
537 members reside on the link connected to the port.
538 permanent - the mdb entry is permanent. Optional for IPv4 and
540 IPv6, mandatory for L2.
541 temp - the mdb entry is temporary (default)
544 src SOURCE
548 optional source IP address of a sender for this multicast group.
549 If IGMPv3 for IPv4, or MLDv2 for IPv6 respectively, are enabled
550 it will be included in the lookup when forwarding multicast
551 traffic.
552 vid VID
555 the VLAN ID which is known to have members of this multicast
556 group.
557 bridge mdb delete - delete a multicast group database entry
560 This command removes an existing mdb entry.
561 The arguments are the same as with bridge mdb add.
564 bridge mdb show - list multicast group database entries
567 This command displays the current multicast group membership table. The
568 table is populated by IGMP and MLD snooping in the bridge driver auto‐
569 matically. It can be altered by bridge mdb add and bridge mdb del com‐
570 mands manually too.
571 dev DEV
574 the interface only whose entries should be listed. Default is to
575 list all bridge interfaces.
576 With the -details option, the command becomes verbose. It prints out
579 the ports known to have a connected router.
580 With the -statistics option, the command displays timer values for mdb
583 and router port entries.
584
587 vlan objects contain known VLAN IDs for a link.
588 The corresponding commands display vlan filter entries, add new en‐
591 tries, and delete old ones.
592 bridge vlan add - add a new vlan filter entry
595 This command creates a new vlan filter entry.
596 dev NAME
599 the interface with which this vlan is associated.
600 vid VID
603 the VLAN ID that identifies the vlan.
604 tunnel_info TUNNEL_ID
607 the TUNNEL ID that maps to this vlan. The tunnel id is set in
608 dst_metadata for every packet that belongs to this vlan (appli‐
609 cable to bridge ports with vlan_tunnel flag set).
610 pvid the vlan specified is to be considered a PVID at ingress. Any
613 untagged frames will be assigned to this VLAN.
614 untagged
617 the vlan specified is to be treated as untagged on egress.
618 self the vlan is configured on the specified physical device. Re‐
621 quired if the device is the bridge device.
622 master the vlan is configured on the software bridge (default).
625 bridge vlan delete - delete a vlan filter entry
628 This command removes an existing vlan filter entry.
629 The arguments are the same as with bridge vlan add. The pvid and un‐
632 tagged flags are ignored.
633 bridge vlan set - change vlan filter entry's options
636 This command changes vlan filter entry's options.
637 dev NAME
640 the interface with which this vlan is associated.
641 vid VID
644 the VLAN ID that identifies the vlan.
645 state STP_STATE
648 the operation state of the vlan. One may enter STP state name
649 (case insensitive), or one of the numbers below. Negative inputs
650 are ignored, and unrecognized names return an error. Note that
651 the state is set only for the vlan of the specified device, e.g.
652 if it is a bridge port then the state will be set only for the
653 vlan of the port.
654 0 - vlan is in STP DISABLED state. Make this vlan completely in‐
656 active for STP. This is also called BPDU filter and could be
657 used to disable STP on an untrusted vlan.
658 1 - vlan is in STP LISTENING state. Only valid if STP is enabled
661 on the bridge. In this state the vlan listens for STP BPDUs and
662 drops all other traffic frames.
663 2 - vlan is in STP LEARNING state. Only valid if STP is enabled
666 on the bridge. In this state the vlan will accept traffic only
667 for the purpose of updating MAC address tables.
668 3 - vlan is in STP FORWARDING state. This is the default vlan
671 state.
672 4 - vlan is in STP BLOCKING state. Only valid if STP is enabled
675 on the bridge. This state is used during the STP election
676 process. In this state, the vlan will only process STP BPDUs.
677 bridge vlan show - list vlan configuration.
681 This command displays the current VLAN filter table.
682 With the -details option, the command becomes verbose. It displays the
685 per-vlan options.
686 With the -statistics option, the command displays per-vlan traffic sta‐
689 tistics.
690 bridge vlan tunnelshow - list vlan tunnel mapping.
693 This command displays the current vlan tunnel info mapping.
694
697 The bridge utility can monitor the state of devices and addresses con‐
698 tinuously. This option has a slightly different format. Namely, the
699 monitor command is the first in the command line and then the object
700 list follows:
701 bridge monitor [ all | OBJECT-LIST ]
703 OBJECT-LIST is the list of object types that we want to monitor. It
705 may contain link, fdb, vlan and mdb. If no file argument is given,
706 bridge opens RTNETLINK, listens on it and dumps state changes in the
707 format described in previous sections.
708 If a file name is given, it does not listen on RTNETLINK, but opens the
711 file containing RTNETLINK messages saved in binary format and dumps
712 them.
713
716 This command uses facilities added in Linux 3.0.
717 Although the forwarding table is maintained on a per-bridge device ba‐
719 sis the bridge device is not part of the syntax. This is a limitation
720 of the underlying netlink neighbour message protocol. When displaying
721 the forwarding table, entries for all bridges are displayed.
722 Add/delete/modify commands determine the underlying bridge device based
723 on the bridge to which the corresponding ethernet device is attached.
724
728 ip(8)
729
731 Please direct bugreports and patches to: <netdev@vger.kernel.org>
732
735 Original Manpage by Stephen Hemminger
736iproute2 1 August 2012 BRIDGE(8)