doc/user/bfd.rst

   1 .. _bfd:
   2
   3 **********************************
   4 Bidirectional Forwarding Detection
   5 **********************************
   6
   7 :abbr:`BFD (Bidirectional Forwarding Detection)` stands for
   8 Bidirectional Forwarding Detection and it is described and extended by
   9 the following RFCs:
  10
  11 * :rfc:`5880`
  12 * :rfc:`5881`
  13 * :rfc:`5882`
  14 * :rfc:`5883`
  15
  16 Currently, there are two implementations of the BFD commands in FRR:
  17
  18 * :abbr:`PTM (Prescriptive Topology Manager)`: an external daemon which
  19   implements BFD;
  20 * ``bfdd``: a BFD implementation that is able to talk with remote peers;
  21
  22 This document will focus on the later implementation: *bfdd*.
  23
  24
  25 .. _bfd-starting:
  26
  27 Starting BFD
  28 ============
  29
  30 *bfdd* default configuration file is :file:`bfdd.conf`. *bfdd* searches
  31 the current directory first then |INSTALL_PREFIX_ETC|/bfdd.conf. All of
  32 *bfdd*'s command must be configured in :file:`bfdd.conf`.
  33
  34 *bfdd* specific invocation options are described below. Common options
  35 may also be specified (:ref:`common-invocation-options`).
  36
  37 .. program:: bfdd
  38
  39 .. option:: --bfdctl <unix-socket>
  40
  41    Set the BFD daemon control socket location. If using a non-default
  42    socket location::
  43
  44       /usr/lib/frr/bfdd --bfdctl /tmp/bfdd.sock
  45
  46
  47    The default UNIX socket location is:
  48
  49       #define BFDD_CONTROL_SOCKET "|INSTALL_PREFIX_STATE|/bfdd.sock"
  50
  51    This option overrides the location addition that the -N option provides
  52    to the bfdd.sock
  53
  54 .. option:: --dplaneaddr <type>:<address>[<:port>]
  55
  56    Configure the distributed BFD data plane listening socket bind address.
  57
  58    One would expect the data plane to run in the same machine as FRR, so
  59    the suggested configuration would be:
  60
  61       --dplaneaddr unix:/var/run/frr/bfdd_dplane.sock
  62
  63    Or using IPv4:
  64
  65       --dplaneaddr ipv4:127.0.0.1
  66
  67    Or using IPv6:
  68
  69       --dplaneaddr ipv6:[::1]
  70
  71    It is also possible to specify a port (for IPv4/IPv6 only):
  72
  73      --dplaneaddr ipv6:[::1]:50701
  74
  75    (if ommited the default port is ``50700``).
  76
  77    It is also possible to operate in client mode (instead of listening for
  78    connections). To connect to a data plane server append the letter 'c' to
  79    the protocol, example:
  80
  81      --dplaneaddr ipv4c:127.0.0.1
  82
  83 .. note::
  84
  85    When using UNIX sockets don't forget to check the file permissions
  86    before attempting to use it.
  87
  88
  89 .. _bfd-commands:
  90
  91 BFDd Commands
  92 =============
  93
  94 .. clicmd:: bfd
  95
  96    Opens the BFD daemon configuration node.
  97
  98 .. clicmd:: peer <A.B.C.D|X:X::X:X> [{multihop|local-address <A.B.C.D|X:X::X:X>|interface IFNAME|vrf NAME}]
  99
 100    Creates and configures a new BFD peer to listen and talk to.
 101
 102    `multihop` tells the BFD daemon that we should expect packets with
 103    TTL less than 254 (because it will take more than one hop) and to
 104    listen on the multihop port (4784). When using multi-hop mode
 105    `echo-mode` will not work (see :rfc:`5883` section 3).
 106
 107    `local-address` provides a local address that we should bind our
 108    peer listener to and the address we should use to send the packets.
 109    This option is mandatory for IPv6.
 110
 111    `interface` selects which interface we should use.
 112
 113    `vrf` selects which domain we want to use.
 114
 115
 116 .. clicmd:: profile WORD
 117
 118    Creates a peer profile that can be configured in multiple peers.
 119
 120    Deleting the profile will cause all peers using it to reset to the default
 121    values.
 122
 123
 124 .. clicmd:: show bfd [vrf NAME] peers [json]
 125
 126     Show all configured BFD peers information and current status.
 127
 128 .. clicmd:: show bfd [vrf NAME] peer <WORD|<A.B.C.D|X:X::X:X> [{multihop|local-address <A.B.C.D|X:X::X:X>|interface IFNAME}]> [json]
 129
 130     Show status for a specific BFD peer.
 131
 132 .. clicmd:: show bfd [vrf NAME] peers brief [json]
 133
 134     Show all configured BFD peers information and current status in brief.
 135
 136 .. clicmd:: show bfd distributed
 137
 138    Show the BFD data plane (distributed BFD) statistics.
 139
 140
 141 .. _bfd-peer-config:
 142
 143 Peer / Profile Configuration
 144 ----------------------------
 145
 146 BFD peers and profiles share the same BFD session configuration commands.
 147
 148 .. clicmd:: detect-multiplier (2-255)
 149
 150    Configures the detection multiplier to determine packet loss. The
 151    remote transmission interval will be multiplied by this value to
 152    determine the connection loss detection timer. The default value is
 153    3.
 154
 155    Example: when the local system has `detect-multiplier 3` and  the
 156    remote system has `transmission interval 300`, the local system will
 157    detect failures only after 900 milliseconds without receiving
 158    packets.
 159
 160 .. clicmd:: receive-interval (10-60000)
 161
 162    Configures the minimum interval that this system is capable of
 163    receiving control packets. The default value is 300 milliseconds.
 164
 165 .. clicmd:: transmit-interval (10-60000)
 166
 167    The minimum transmission interval (less jitter) that this system
 168    wants to use to send BFD control packets. Defaults to 300ms.
 169
 170 .. clicmd:: echo receive-interval <disabled|(10-60000)>
 171
 172    Configures the minimum interval that this system is capable of
 173    receiving echo packets. Disabled means that this system doesn't want
 174    to receive echo packets. The default value is 50 milliseconds.
 175
 176 .. clicmd:: echo transmit-interval (10-60000)
 177
 178    The minimum transmission interval (less jitter) that this system
 179    wants to use to send BFD echo packets. Defaults to 50ms.
 180
 181 .. clicmd:: echo-mode
 182
 183    Enables or disables the echo transmission mode. This mode is disabled
 184    by default. If you are not using distributed BFD then echo mode works
 185    only when the peer is also FRR.
 186
 187    It is recommended that the transmission interval of control packets
 188    to be increased after enabling echo-mode to reduce bandwidth usage.
 189    For example: `transmit-interval 2000`.
 190
 191    Echo mode is not supported on multi-hop setups (see :rfc:`5883`
 192    section 3).
 193
 194 .. clicmd:: shutdown
 195
 196    Enables or disables the peer. When the peer is disabled an
 197    'administrative down' message is sent to the remote peer.
 198
 199
 200 .. clicmd:: passive-mode
 201
 202    Mark session as passive: a passive session will not attempt to start
 203    the connection and will wait for control packets from peer before it
 204    begins replying.
 205
 206    This feature is useful when you have a router that acts as the
 207    central node of a star network and you want to avoid sending BFD
 208    control packets you don't need to.
 209
 210    The default is active-mode (or ``no passive-mode``).
 211
 212 .. clicmd:: minimum-ttl (1-254)
 213
 214    For multi hop sessions only: configure the minimum expected TTL for
 215    an incoming BFD control packet.
 216
 217    This feature serves the purpose of thightening the packet validation
 218    requirements to avoid receiving BFD control packets from other
 219    sessions.
 220
 221    The default value is 254 (which means we only expect one hop between
 222    this system and the peer).
 223
 224
 225 BFD Peer Specific Commands
 226 --------------------------
 227
 228 .. clicmd:: label WORD
 229
 230    Labels a peer with the provided word. This word can be referenced
 231    later on other daemons to refer to a specific peer.
 232
 233
 234 .. clicmd:: profile BFDPROF
 235
 236    Configure peer to use the profile configurations.
 237
 238    Notes:
 239
 240    - Profile configurations can be overridden on a peer basis by specifying
 241      non-default parameters in peer configuration node.
 242    - Non existing profiles can be configured and they will only be applied
 243      once they start to exist.
 244    - If the profile gets updated the new configuration will be applied to all
 245      peers with the profile without interruptions.
 246
 247
 248 .. _bfd-bgp-peer-config:
 249
 250 BGP BFD Configuration
 251 ---------------------
 252
 253 The following commands are available inside the BGP configuration node.
 254
 255 .. clicmd:: neighbor <A.B.C.D|X:X::X:X|WORD> bfd
 256
 257    Listen for BFD events registered on the same target as this BGP
 258    neighbor. When BFD peer goes down it immediately asks BGP to shutdown
 259    the connection with its neighbor and, when it goes back up, notify
 260    BGP to try to connect to it.
 261
 262
 263 .. clicmd:: neighbor <A.B.C.D|X:X::X:X|WORD> bfd check-control-plane-failure
 264
 265    Allow to write CBIT independence in BFD outgoing packets. Also allow to
 266    read both C-BIT value of BFD and lookup BGP peer status. This command is
 267    useful when a BFD down event is caught, while the BGP peer requested that
 268    local BGP keeps the remote BGP entries as staled if such issue is detected.
 269    This is the case when graceful restart is enabled, and it is wished to
 270    ignore the BD event while waiting for the remote router to restart.
 271
 272    Disabling this disables presence of CBIT independence in BFD outgoing
 273    packets and pays attention to BFD down notifications. This is the default.
 274
 275
 276 .. clicmd:: neighbor <A.B.C.D|X:X::X:X|WORD> bfd profile BFDPROF
 277
 278    Same as command ``neighbor <A.B.C.D|X:X::X:X|WORD> bfd``, but applies the
 279    BFD profile to the sessions it creates or that already exist.
 280
 281
 282 .. _bfd-isis-peer-config:
 283
 284 IS-IS BFD Configuration
 285 -----------------------
 286
 287 The following commands are available inside the interface configuration node.
 288
 289 .. clicmd:: isis bfd
 290
 291    Listen for BFD events on peers created on the interface. Every time
 292    a new neighbor is found a BFD peer is created to monitor the link
 293    status for fast convergence.
 294
 295    Note that there will be just one BFD session per interface. In case both
 296    IPv4 and IPv6 support are configured then just a IPv6 based session is
 297    created.
 298
 299 .. clicmd:: isis bfd profile BFDPROF
 300
 301    Use a BFD profile BFDPROF as provided in the BFD configuration.
 302
 303
 304 .. _bfd-ospf-peer-config:
 305
 306 OSPF BFD Configuration
 307 ----------------------
 308
 309 The following commands are available inside the interface configuration node.
 310
 311 .. clicmd:: ip ospf bfd
 312
 313    Listen for BFD events on peers created on the interface. Every time
 314    a new neighbor is found a BFD peer is created to monitor the link
 315    status for fast convergence.
 316
 317 .. clicmd:: ip ospf bfd profile BFDPROF
 318
 319    Same as command ``ip ospf bfd``, but applies the BFD profile to the sessions
 320    it creates or that already exist.
 321
 322
 323 .. _bfd-ospf6-peer-config:
 324
 325 OSPF6 BFD Configuration
 326 -----------------------
 327
 328 The following commands are available inside the interface configuration node.
 329
 330 .. clicmd:: ipv6 ospf6 bfd [profile BFDPROF]
 331
 332    Listen for BFD events on peers created on the interface. Every time
 333    a new neighbor is found a BFD peer is created to monitor the link
 334    status for fast convergence.
 335
 336    Optionally uses the BFD profile ``BFDPROF`` in the created sessions under
 337    that interface.
 338
 339
 340 .. _bfd-pim-peer-config:
 341
 342 PIM BFD Configuration
 343 ---------------------
 344
 345 The following commands are available inside the interface configuration node.
 346
 347 .. clicmd:: ip pim bfd [profile BFDPROF]
 348
 349    Listen for BFD events on peers created on the interface. Every time
 350    a new neighbor is found a BFD peer is created to monitor the link
 351    status for fast convergence.
 352
 353    Optionally uses the BFD profile ``BFDPROF`` in the created sessions under
 354    that interface.
 355
 356
 357 .. _bfd-rip-peer-config:
 358
 359 RIP BFD configuration
 360 ---------------------
 361
 362 The following commands are available inside the interface configuration node:
 363
 364 .. clicmd:: ip rip bfd
 365
 366    Automatically create BFD session for each RIP peer discovered in this
 367    interface. When the BFD session monitor signalize that the link is down
 368    the RIP peer is removed and all the learned routes associated with that
 369    peer are removed.
 370
 371
 372 .. clicmd:: ip rip bfd profile BFD_PROFILE_NAME
 373
 374    Selects a BFD profile for the BFD sessions created in this interface.
 375
 376
 377 The following command is available in the RIP router configuration node:
 378
 379 .. clicmd:: bfd default-profile BFD_PROFILE_NAME
 380
 381    Selects a default BFD profile for all sessions without a profile specified.
 382
 383
 384 .. _bfd-static-peer-config:
 385
 386 BFD Static Route Monitoring Configuration
 387 -----------------------------------------
 388
 389 A monitored static route conditions the installation to the RIB on the
 390 BFD session running state: when BFD session is up the route is installed
 391 to RIB, but when the BFD session is down it is removed from the RIB.
 392
 393 The following commands are available inside the configuration node:
 394
 395 .. clicmd:: ip route A.B.C.D/M A.B.C.D bfd [{multi-hop|source A.B.C.D|profile BFDPROF}]
 396
 397    Configure a static route for ``A.B.C.D/M`` using gateway ``A.B.C.D`` and use
 398    the gateway address as BFD peer destination address.
 399
 400 .. clicmd:: ipv6 route X:X::X:X/M [from X:X::X:X/M] X:X::X:X bfd [{multi-hop|source X:X::X:X|profile BFDPROF}]
 401
 402    Configure a static route for ``X:X::X:X/M`` using gateway
 403    ``X:X::X:X`` and use the gateway address as BFD peer destination
 404    address.
 405
 406 The static routes when uninstalled will no longer show up in the output of
 407 the command ``show ip route`` or ``show ipv6 route``, instead we must use the
 408 BFD static route show command to see these monitored route status.
 409
 410 .. clicmd:: show bfd static route [json]
 411
 412    Show all monitored static routes and their status.
 413
 414    Example output:
 415
 416    ::
 417
 418       Showing BFD monitored static routes:
 419
 420         Route groups:
 421           rtg1 peer 172.16.0.1 (status: uninstalled):
 422               2001:db8::100/128
 423
 424       Next hops:
 425         VRF default IPv4 Unicast:
 426             192.168.100.0/24 peer 172.16.0.1 (status: uninstalled)
 427
 428         VRF default IPv4 Multicast:
 429
 430         VRF default IPv6 Unicast:
 431
 432 .. _bfd-configuration:
 433
 434 Configuration
 435 =============
 436
 437 Before applying ``bfdd`` rules to integrated daemons (like BGPd), we must
 438 create the corresponding peers inside the ``bfd`` configuration node.
 439
 440 Here is an example of BFD configuration:
 441
 442 ::
 443
 444     bfd
 445      peer 192.168.0.1
 446        label home-peer
 447        no shutdown
 448      !
 449     !
 450     router bgp 65530
 451      neighbor 192.168.0.1 remote-as 65531
 452      neighbor 192.168.0.1 bfd
 453      neighbor 192.168.0.2 remote-as 65530
 454      neighbor 192.168.0.2 bfd
 455      neighbor 192.168.0.3 remote-as 65532
 456      neighbor 192.168.0.3 bfd
 457     !
 458
 459 Peers can be identified by its address (use ``multihop`` when you need
 460 to specify a multi hop peer) or can be specified manually by a label.
 461
 462 Here are the available peer configurations:
 463
 464 ::
 465
 466    bfd
 467     ! Configure a fast profile
 468     profile fast
 469      receive-interval 150
 470      transmit-interval 150
 471     !
 472
 473     ! Configure peer with fast profile
 474     peer 192.168.0.6
 475      profile fast
 476      no shutdown
 477     !
 478
 479    ! Configure peer with fast profile and override receive speed.
 480     peer 192.168.0.7
 481      profile fast
 482      receive-interval 500
 483      no shutdown
 484     !
 485
 486     ! configure a peer on an specific interface
 487     peer 192.168.0.1 interface eth0
 488      no shutdown
 489     !
 490
 491     ! configure a multihop peer
 492     peer 192.168.0.2 multihop local-address 192.168.0.3
 493       shutdown
 494     !
 495
 496     ! configure a peer in a different vrf
 497     peer 192.168.0.3 vrf foo
 498      shutdown
 499     !
 500
 501     ! configure a peer with every option possible
 502     peer 192.168.0.4
 503      label peer-label
 504      detect-multiplier 50
 505      receive-interval 60000
 506      transmit-interval 3000
 507      shutdown
 508     !
 509
 510     ! configure a peer on an interface from a separate vrf
 511     peer 192.168.0.5 interface eth1 vrf vrf2
 512      no shutdown
 513     !
 514
 515     ! remove a peer
 516     no peer 192.168.0.3 vrf foo
 517
 518
 519 .. _bfd-status:
 520
 521 Status
 522 ======
 523
 524 You can inspect the current BFD peer status with the following commands:
 525
 526 ::
 527
 528    frr# show bfd peers
 529    BFD Peers:
 530            peer 192.168.0.1
 531                    ID: 1
 532                    Remote ID: 1
 533                    Status: up
 534                    Uptime: 1 minute(s), 51 second(s)
 535                    Diagnostics: ok
 536                    Remote diagnostics: ok
 537                    Peer Type: dynamic
 538                    Local timers:
 539                            Detect-multiplier: 3
 540                            Receive interval: 300ms
 541                            Transmission interval: 300ms
 542                            Echo receive interval: 50ms
 543                            Echo transmission interval: disabled
 544                    Remote timers:
 545                            Detect-multiplier: 3
 546                            Receive interval: 300ms
 547                            Transmission interval: 300ms
 548                            Echo receive interval: 50ms
 549
 550            peer 192.168.1.1
 551                    label: router3-peer
 552                    ID: 2
 553                    Remote ID: 2
 554                    Status: up
 555                    Uptime: 1 minute(s), 53 second(s)
 556                    Diagnostics: ok
 557                    Remote diagnostics: ok
 558                    Peer Type: configured
 559                    Local timers:
 560                            Detect-multiplier: 3
 561                            Receive interval: 300ms
 562                            Transmission interval: 300ms
 563                            Echo receive interval: 50ms
 564                            Echo transmission interval: disabled
 565                    Remote timers:
 566                            Detect-multiplier: 3
 567                            Receive interval: 300ms
 568                            Transmission interval: 300ms
 569                            Echo receive interval: 50ms
 570
 571    frr# show bfd peer 192.168.1.1
 572    BFD Peer:
 573                peer 192.168.1.1
 574                    label: router3-peer
 575                    ID: 2
 576                    Remote ID: 2
 577                    Status: up
 578                    Uptime: 3 minute(s), 4 second(s)
 579                    Diagnostics: ok
 580                    Remote diagnostics: ok
 581                    Peer Type: dynamic
 582                    Local timers:
 583                            Detect-multiplier: 3
 584                            Receive interval: 300ms
 585                            Transmission interval: 300ms
 586                            Echo receive interval: 50ms
 587                            Echo transmission interval: disabled
 588                    Remote timers:
 589                            Detect-multiplier: 3
 590                            Receive interval: 300ms
 591                            Transmission interval: 300ms
 592                            Echo receive interval: 50ms
 593
 594    frr# show bfd peer 192.168.0.1 json
 595    {"multihop":false,"peer":"192.168.0.1","id":1,"remote-id":1,"status":"up","uptime":161,"diagnostic":"ok","remote-diagnostic":"ok","receive-interval":300,"transmit-interval":300,"echo-receive-interval":50,"echo-transmit-interval":0,"detect-multiplier":3,"remote-receive-interval":300,"remote-transmit-interval":300,"remote-echo-receive-interval":50,"remote-detect-multiplier":3,"peer-type":"dynamic"}
 596
 597 If you are running IPV4 BFD Echo, on a Linux platform, we also
 598 calculate round trip time for the packets.  We display minimum,
 599 average and maximum time it took to receive the looped Echo packets
 600 in the RTT fields.
 601
 602 You can inspect the current BFD peer status in brief with the following commands:
 603
 604 ::
 605
 606    frr# show bfd peers brief
 607    Session count: 1
 608    SessionId  LocalAddress         PeerAddress      Status
 609    =========  ============         ===========      ======
 610    1          192.168.0.1          192.168.0.2      up
 611
 612
 613 You can also inspect peer session counters with the following commands:
 614
 615 ::
 616
 617    frr# show bfd peers counters
 618    BFD Peers:
 619         peer 192.168.2.1 interface r2-eth2
 620                 Control packet input: 28 packets
 621                 Control packet output: 28 packets
 622                 Echo packet input: 0 packets
 623                 Echo packet output: 0 packets
 624                 Session up events: 1
 625                 Session down events: 0
 626                 Zebra notifications: 2
 627
 628         peer 192.168.0.1
 629                 Control packet input: 54 packets
 630                 Control packet output: 103 packets
 631                 Echo packet input: 965 packets
 632                 Echo packet output: 966 packets
 633                 Session up events: 1
 634                 Session down events: 0
 635                 Zebra notifications: 4
 636
 637    frr# show bfd peer 192.168.0.1 counters
 638         peer 192.168.0.1
 639                 Control packet input: 126 packets
 640                 Control packet output: 247 packets
 641                 Echo packet input: 2409 packets
 642                 Echo packet output: 2410 packets
 643                 Session up events: 1
 644                 Session down events: 0
 645                 Zebra notifications: 4
 646
 647    frr# show bfd peer 192.168.0.1 counters json
 648    {"multihop":false,"peer":"192.168.0.1","control-packet-input":348,"control-packet-output":685,"echo-packet-input":6815,"echo-packet-output":6816,"session-up":1,"session-down":0,"zebra-notifications":4}
 649
 650 You can also clear packet counters per session with the following commands, only the packet counters will be reset:
 651
 652 ::
 653
 654    frr# clear bfd peers counters
 655
 656    frr# show bfd peers counters
 657    BFD Peers:
 658         peer 192.168.2.1 interface r2-eth2
 659                 Control packet input: 0 packets
 660                 Control packet output: 0 packets
 661                 Echo packet input: 0 packets
 662                 Echo packet output: 0 packets
 663                 Session up events: 1
 664                 Session down events: 0
 665                 Zebra notifications: 2
 666
 667         peer 192.168.0.1
 668                 Control packet input: 0 packets
 669                 Control packet output: 0 packets
 670                 Echo packet input: 0 packets
 671                 Echo packet output: 0 packets
 672                 Session up events: 1
 673                 Session down events: 0
 674                 Zebra notifications: 4
 675
 676
 677 .. _bfd-distributed:
 678
 679 Distributed BFD
 680 ===============
 681
 682 The distributed BFD is the separation of the BFD protocol control plane from
 683 the data plane. FRR implements its own BFD data plane protocol so vendors can
 684 study and include it in their own software/hardware without having to modify
 685 the FRR source code. The protocol definitions can be found at
 686 ``bfdd/bfddp_packet.h`` header (or the installed
 687 ``/usr/include/frr/bfdd/bfddp_packet.h``).
 688
 689 To use this feature the BFD daemon needs to be started using the command line
 690 option :option:`--dplaneaddr`. When operating using this option the BFD daemon
 691 will not attempt to establish BFD sessions, but it will offload all its work to
 692 the data plane that is (or will be) connected. Data plane reconnection is also
 693 supported.
 694
 695 The BFD data plane will be responsible for:
 696
 697 * Sending/receiving the BFD protocol control/echo packets
 698
 699 * Notifying BFD sessions state changes
 700
 701 * Keeping the number of packets/bytes received/transmitted per session
 702
 703
 704 The FRR BFD daemon will be responsible for:
 705
 706 * Adding/updating BFD session settings
 707
 708 * Asking for BFD session counters
 709
 710 * Redistributing the state changes to the integrated protocols (``bgpd``,
 711   ``ospfd`` etc...)
 712
 713
 714 BFD daemon will also keep record of data plane communication statistics with
 715 the command :clicmd:`show bfd distributed`.
 716
 717 Sample output:
 718
 719 ::
 720
 721    frr# show bfd distributed
 722                Data plane
 723                ==========
 724           File descriptor: 16
 725               Input bytes: 1296
 726          Input bytes peak: 72
 727            Input messages: 42
 728       Input current usage: 0
 729              Output bytes: 568
 730         Output bytes peak: 136
 731           Output messages: 19
 732        Output full events: 0
 733      Output current usage: 0
 734
 735
 736 .. _bfd-debugging:
 737
 738 Debugging
 739 =========
 740
 741 By default only informational, warning and errors messages are going to be
 742 displayed. If you want to get debug messages and other diagnostics then make
 743 sure you have `debugging` level enabled:
 744
 745 ::
 746
 747    config
 748    log file /var/log/frr/frr.log debugging
 749    log syslog debugging
 750
 751 You may also fine tune the debug messages by selecting one or more of the
 752 debug levels:
 753
 754 .. clicmd:: debug bfd distributed
 755
 756    Toggle BFD data plane (distributed BFD) debugging.
 757
 758    Activates the following debug messages:
 759
 760    * Data plane received / send messages
 761    * Connection events
 762
 763 .. clicmd:: debug bfd network
 764
 765    Toggle network events: show messages about socket failures and unexpected
 766    BFD messages that may not belong to registered peers.
 767
 768 .. clicmd:: debug bfd peer
 769
 770    Toggle peer event log messages: show messages about peer creation/removal
 771    and state changes.
 772
 773 .. clicmd:: debug bfd zebra
 774
 775    Toggle zebra message events: show messages about interfaces, local
 776    addresses, VRF and daemon peer registrations.