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 [ show | tunnelshow ] [ dev DEV ]
49 bridge monitor [ all | neigh | link | mdb ]
51
54 -V, -Version
55 print the version of the bridge utility and exit.
56 -s, -stats, -statistics
59 output more information. If this option is given multiple times,
60 the amount of information increases. As a rule, the information
61 is statistics or some time values.
62 -d, -details
65 print detailed information about MDB router ports.
66 -n, -net, -netns <NETNS>
69 switches bridge to the specified network namespace NETNS. Actu‐
70 ally it just simplifies executing of:
71 ip netns exec NETNS bridge [ OPTIONS ] OBJECT { COMMAND | help }
73 to
75 bridge -n[etns] NETNS [ OPTIONS ] OBJECT { COMMAND | help }
77 -b, -batch <FILENAME>
80 Read commands from provided file or standard input and invoke
81 them. First failure will cause termination of bridge command.
82 -force Don't terminate bridge command on errors in batch mode. If
85 there were any errors during execution of the commands, the ap‐
86 plication return code will be non zero.
87 -c[color][={always|auto|never}
90 Configure color output. If parameter is omitted or always, color
91 output is enabled regardless of stdout state. If parameter is
92 auto, stdout is checked to be a terminal before enabling color
93 output. If parameter is never, color output is disabled. If
94 specified multiple times, the last one takes precedence. This
95 flag is ignored if -json is also given.
96 -j, -json
99 Output results in JavaScript Object Notation (JSON).
100 -p, -pretty
103 When combined with -j generate a pretty JSON output.
104 -o, -oneline
107 output each record on a single line, replacing line feeds with
108 the '\' character. This is convenient when you want to count
109 records with wc(1) or to grep(1) the output.
110
114 OBJECT
115 link - Bridge port.
116 fdb - Forwarding Database entry.
119 mdb - Multicast group database entry.
122 vlan - VLAN filter list.
125 COMMAND
128 Specifies the action to perform on the object. The set of possible ac‐
129 tions depends on the object type. As a rule, it is possible to add,
130 delete and show (or list ) objects, but some objects do not allow all
131 of these operations or have some additional commands. The help command
132 is available for all objects. It prints out a list of available com‐
133 mands and argument syntax conventions.
134 If no command is given, some default command is assumed. Usually it is
136 list or, if the objects of this class cannot be listed, help.
137
140 link objects correspond to the port devices of the bridge.
141 The corresponding commands set and display port status and bridge spe‐
144 cific attributes.
145 bridge link set - set bridge specific attributes on a port
148 dev NAME
149 interface name of the bridge port
150 cost COST
153 the STP path cost of the specified port.
154 priority PRIO
157 the STP port priority. The priority value is an unsigned 8-bit
158 quantity (number between 0 and 255). This metric is used in the
159 designated port an droot port selection algorithms.
160 state STATE
163 the operation state of the port. Except state 0 (disable STP or
164 BPDU filter feature), this is primarily used by user space
165 STP/RSTP implementation. One may enter port state name (case in‐
166 sensitive), or one of the numbers below. Negative inputs are ig‐
167 nored, and unrecognized names return an error.
168 0 - port is in STP DISABLED state. Make this port completely in‐
170 active for STP. This is also called BPDU filter and could be
171 used to disable STP on an untrusted port, like a leaf virtual
172 devices.
173 1 - port is in STP LISTENING state. Only valid if STP is enabled
176 on the bridge. In this state the port listens for STP BPDUs and
177 drops all other traffic frames.
178 2 - port is in STP LEARNING state. Only valid if STP is enabled
181 on the bridge. In this state the port will accept traffic only
182 for the purpose of updating MAC address tables.
183 3 - port is in STP FORWARDING state. Port is fully active.
186 4 - port is in STP BLOCKING state. Only valid if STP is enabled
189 on the bridge. This state is used during the STP election
190 process. In this state, port will only process STP BPDUs.
191 guard on or guard off
195 Controls whether STP BPDUs will be processed by the bridge port.
196 By default, the flag is turned off allowed BPDU processing.
197 Turning this flag on will disables the bridge port if a STP BPDU
198 packet is received.
199 If running Spanning Tree on bridge, hostile devices on the net‐
201 work may send BPDU on a port and cause network failure. Setting
202 guard on will detect and stop this by disabling the port. The
203 port will be restarted if link is brought down, or removed and
204 reattached. For example if guard is enable on eth0:
205 ip link set dev eth0 down; ip link set dev eth0 up
207 hairpin on or hairpin off
210 Controls whether traffic may be send back out of the port on
211 which it was received. This option is also called reflective re‐
212 lay mode, and is used to support basic VEPA (Virtual Ethernet
213 Port Aggregator) capabilities. By default, this flag is turned
214 off and the bridge will not forward traffic back out of the re‐
215 ceiving port.
216 fastleave on or fastleave off
219 This flag allows the bridge to immediately stop multicast traf‐
220 fic on a port that receives IGMP Leave message. It is only used
221 with IGMP snooping is enabled on the bridge. By default the flag
222 is off.
223 root_block on or root_block off
226 Controls whether a given port is allowed to become root port or
227 not. Only used when STP is enabled on the bridge. By default the
228 flag is off.
229 This feature is also called root port guard. If BPDU is re‐
231 ceived from a leaf (edge) port, it should not be elected as root
232 port. This could be used if using STP on a bridge and the down‐
233 stream bridges are not fully trusted; this prevents a hostile
234 guest from rerouting traffic.
235 learning on or learning off
238 Controls whether a given port will learn MAC addresses from re‐
239 ceived traffic or not. If learning if off, the bridge will end
240 up flooding any traffic for which it has no FDB entry. By de‐
241 fault this flag is on.
242 learning_sync on or learning_sync off
245 Controls whether a given port will sync MAC addresses learned on
246 device port to bridge FDB.
247 flood on or flood off
250 Controls whether a given port will flood unicast traffic for
251 which there is no FDB entry. By default this flag is on.
252 hwmode Some network interface cards support HW bridge functionality and
255 they may be configured in different modes. Currently support
256 modes are:
257 vepa - Data sent between HW ports is sent on the wire to the ex‐
259 ternal switch.
260 veb - bridging happens in hardware.
262 mcast_flood on or mcast_flood off
265 Controls whether a given port will flood multicast traffic for
266 which there is no MDB entry. By default this flag is on.
267 mcast_to_unicast on or mcast_to_unicast off
270 Controls whether a given port will replicate packets using uni‐
271 cast instead of multicast. By default this flag is off.
272 This is done by copying the packet per host and changing the
274 multicast destination MAC to a unicast one accordingly.
275 mcast_to_unicast works on top of the multicast snooping feature
277 of the bridge. Which means unicast copies are only delivered to
278 hosts which are interested in it and signalized this via
279 IGMP/MLD reports previously.
280 This feature is intended for interface types which have a more
282 reliable and/or efficient way to deliver unicast packets than
283 broadcast ones (e.g. WiFi).
284 However, it should only be enabled on interfaces where no
286 IGMPv2/MLDv1 report suppression takes place. IGMP/MLD report
287 suppression issue is usually overcome by the network daemon
288 (supplicant) enabling AP isolation and by that separating all
289 STAs.
290 Delivery of STA-to-STA IP multicast is made possible again by
292 enabling and utilizing the bridge hairpin mode, which considers
293 the incoming port as a potential outgoing port, too (see hairpin
294 option). Hairpin mode is performed after multicast snooping,
295 therefore leading to only deliver reports to STAs running a mul‐
296 ticast router.
297 neigh_suppress on or neigh_suppress off
300 Controls whether neigh discovery (arp and nd) proxy and suppres‐
301 sion is enabled on the port. By default this flag is off.
302 vlan_tunnel on or vlan_tunnel off
305 Controls whether vlan to tunnel mapping is enabled on the port.
306 By default this flag is off.
307 isolated on or isolated off
310 Controls whether a given port will be isolated, which means it
311 will be able to communicate with non-isolated ports only. By
312 default this flag is off.
313 backup_port DEVICE
316 If the port loses carrier all traffic will be redirected to the
317 configured backup port
318 nobackup_port
321 Removes the currently configured backup port
322 self link setting is configured on specified physical device
325 master link setting is configured on the software bridge (default)
328 -t, -timestamp
331 display current time when using monitor option.
332 bridge link show - list ports configuration for all bridges.
335 This command displays port configuration and flags for all bridges.
336 To display port configuration and flags for a specific bridge, use the
338 "ip link show master <bridge_device>" command.
339
342 fdb objects contain known Ethernet addresses on a link.
343 The corresponding commands display fdb entries, add new entries, append
346 entries, and delete old ones.
347 bridge fdb add - add a new fdb entry
350 This command creates a new fdb entry.
351 LLADDR the Ethernet MAC address.
354 dev DEV
357 the interface to which this address is associated.
358 local - is a local permanent fdb entry
360 static - is a static (no arp) fdb entry
363 dynamic - is a dynamic reachable age-able fdb entry
366 self - the address is associated with the port drivers fdb. Usu‐
369 ally hardware.
370 master - the address is associated with master devices fdb. Usu‐
373 ally software (default).
374 router - the destination address is associated with a router.
377 Valid if the referenced device is a VXLAN type device and has
378 route short circuit enabled.
379 use - the address is in use. User space can use this option to
382 indicate to the kernel that the fdb entry is in use.
383 extern_learn - this entry was learned externally. This option
386 can be used to indicate to the kernel that an entry was hardware
387 or user-space controller learnt dynamic entry. Kernel will not
388 age such an entry.
389 sticky - this entry will not change its port due to learning.
392 The next command line parameters apply only when the specified device
395 DEV is of type VXLAN.
396 dst IPADDR
398 the IP address of the destination VXLAN tunnel endpoint where
399 the Ethernet MAC ADDRESS resides.
400 src_vni VNI
403 the src VNI Network Identifier (or VXLAN Segment ID) this entry
404 belongs to. Used only when the vxlan device is in external or
405 collect metadata mode. If omitted the value specified at vxlan
406 device creation will be used.
407 vni VNI
410 the VXLAN VNI Network Identifier (or VXLAN Segment ID) to use to
411 connect to the remote VXLAN tunnel endpoint. If omitted the
412 value specified at vxlan device creation will be used.
413 port PORT
416 the UDP destination PORT number to use to connect to the remote
417 VXLAN tunnel endpoint. If omitted the default value is used.
418 via DEVICE
421 device name of the outgoing interface for the VXLAN device
422 driver to reach the remote VXLAN tunnel endpoint.
423 nhid NHID
426 ecmp nexthop group for the VXLAN device driver to reach remote
427 VXLAN tunnel endpoints.
428 bridge fdb append - append a forwarding database entry
431 This command adds a new fdb entry with an already known LLADDR. Valid
432 only for multicast link layer addresses. The command adds support for
433 broadcast and multicast Ethernet MAC addresses. The Ethernet MAC ad‐
434 dress is added multiple times into the forwarding database and the
435 vxlan device driver sends a copy of the data packet to each entry
436 found.
437 The arguments are the same as with bridge fdb add.
440 bridge fdb delete - delete a forwarding database entry
443 This command removes an existing fdb entry.
444 The arguments are the same as with bridge fdb add.
447 bridge fdb replace - replace a forwarding database entry
450 If no matching entry is found, a new one will be created instead.
451 The arguments are the same as with bridge fdb add.
454 bridge fdb show - list forwarding entries.
457 This command displays the current forwarding table.
458 With the -statistics option, the command becomes verbose. It prints out
461 the last updated and last used time for each entry.
462 bridge fdb get - get bridge forwarding entry.
465 lookup a bridge forwarding table entry.
466 LLADDR the Ethernet MAC address.
469 dev DEV
472 the interface to which this address is associated.
473 brport DEV
476 the bridge port to which this address is associated. same as dev
477 above.
478 br DEV the bridge to which this address is associated.
481 self - the address is associated with the port drivers fdb. Usually
484 hardware.
485 master - the address is associated with master devices fdb. Usually
488 software (default).
489
493 mdb objects contain known IP multicast group addresses on a link.
494 The corresponding commands display mdb entries, add new entries, and
497 delete old ones.
498 bridge mdb add - add a new multicast group database entry
501 This command creates a new mdb entry.
502 dev DEV
505 the interface where this group address is associated.
506 port PORT
509 the port whose link is known to have members of this multicast
510 group.
511 grp GROUP
514 the IP multicast group address whose members reside on the link
515 connected to the port.
516 permanent - the mdb entry is permanent
518 temp - the mdb entry is temporary (default)
521 src SOURCE
525 optional source IP address of a sender for this multicast group.
526 If IGMPv3 for IPv4, or MLDv2 for IPv6 respectively, are enabled
527 it will be included in the lookup when forwarding multicast
528 traffic.
529 vid VID
532 the VLAN ID which is known to have members of this multicast
533 group.
534 bridge mdb delete - delete a multicast group database entry
537 This command removes an existing mdb entry.
538 The arguments are the same as with bridge mdb add.
541 bridge mdb show - list multicast group database entries
544 This command displays the current multicast group membership table. The
545 table is populated by IGMP and MLD snooping in the bridge driver auto‐
546 matically. It can be altered by bridge mdb add and bridge mdb del com‐
547 mands manually too.
548 dev DEV
551 the interface only whose entries should be listed. Default is to
552 list all bridge interfaces.
553 With the -details option, the command becomes verbose. It prints out
556 the ports known to have a connected router.
557 With the -statistics option, the command displays timer values for mdb
560 and router port entries.
561
564 vlan objects contain known VLAN IDs for a link.
565 The corresponding commands display vlan filter entries, add new en‐
568 tries, and delete old ones.
569 bridge vlan add - add a new vlan filter entry
572 This command creates a new vlan filter entry.
573 dev NAME
576 the interface with which this vlan is associated.
577 vid VID
580 the VLAN ID that identifies the vlan.
581 tunnel_info TUNNEL_ID
584 the TUNNEL ID that maps to this vlan. The tunnel id is set in
585 dst_metadata for every packet that belongs to this vlan (appli‐
586 cable to bridge ports with vlan_tunnel flag set).
587 pvid the vlan specified is to be considered a PVID at ingress. Any
590 untagged frames will be assigned to this VLAN.
591 untagged
594 the vlan specified is to be treated as untagged on egress.
595 self the vlan is configured on the specified physical device. Re‐
598 quired if the device is the bridge device.
599 master the vlan is configured on the software bridge (default).
602 bridge vlan delete - delete a vlan filter entry
605 This command removes an existing vlan filter entry.
606 The arguments are the same as with bridge vlan add. The pvid and un‐
609 tagged flags are ignored.
610 bridge vlan show - list vlan configuration.
613 This command displays the current VLAN filter table.
614 With the -statistics option, the command displays per-vlan traffic sta‐
617 tistics.
618 bridge vlan tunnelshow - list vlan tunnel mapping.
621 This command displays the current vlan tunnel info mapping.
622
625 The bridge utility can monitor the state of devices and addresses con‐
626 tinuously. This option has a slightly different format. Namely, the
627 monitor command is the first in the command line and then the object
628 list follows:
629 bridge monitor [ all | OBJECT-LIST ]
631 OBJECT-LIST is the list of object types that we want to monitor. It
633 may contain link, fdb, and mdb. If no file argument is given, bridge
634 opens RTNETLINK, listens on it and dumps state changes in the format
635 described in previous sections.
636 If a file name is given, it does not listen on RTNETLINK, but opens the
639 file containing RTNETLINK messages saved in binary format and dumps
640 them.
641
644 This command uses facilities added in Linux 3.0.
645 Although the forwarding table is maintained on a per-bridge device ba‐
647 sis the bridge device is not part of the syntax. This is a limitation
648 of the underlying netlink neighbour message protocol. When displaying
649 the forwarding table, entries for all bridges are displayed.
650 Add/delete/modify commands determine the underlying bridge device based
651 on the bridge to which the corresponding ethernet device is attached.
652
656 ip(8)
657
659 Please direct bugreports and patches to: <netdev@vger.kernel.org>
660
663 Original Manpage by Stephen Hemminger
664iproute2 1 August 2012 BRIDGE(8)