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:`5883`
  14
  15 Currently, there are two implementations of the BFD commands in FRR:
  16
  17 * :abbr:`PTM (Prescriptive Topology Manager)`: an external daemon which
  18   implements BFD;
  19 * ``bfdd``: a BFD implementation that is able to talk with remote peers;
  20
  21 This document will focus on the later implementation: *bfdd*.
  22
  23
  24 .. _bfd-starting:
  25
  26 Starting BFD
  27 ============
  28
  29 *bfdd* default configuration file is :file:`bfdd.conf`. *bfdd* searches
  30 the current directory first then |INSTALL_PREFIX_ETC|/bfdd.conf. All of
  31 *bfdd*'s command must be configured in :file:`bfdd.conf`.
  32
  33 *bfdd* specific invocation options are described below. Common options
  34 may also be specified (:ref:`common-invocation-options`).
  35
  36 .. program:: bfdd
  37
  38 .. option:: --bfdctl <unix-socket>
  39
  40    Set the BFD daemon control socket location. If using a non-default
  41    socket location::
  42
  43       /usr/lib/frr/bfdd --bfdctl /tmp/bfdd.sock
  44
  45
  46    The default UNIX socket location is:
  47
  48       #define BFDD_CONTROL_SOCKET "|INSTALL_PREFIX_STATE|/bfdd.sock"
  49
  50
  51 .. _bfd-commands:
  52
  53 BFDd Commands
  54 =============
  55
  56 .. index:: bfd
  57 .. clicmd:: bfd
  58
  59    Opens the BFD daemon configuration node.
  60
  61 .. index:: peer <A.B.C.D|X:X::X:X> [{multihop|local-address <A.B.C.D|X:X::X:X>|interface IFNAME|vrf NAME}]
  62 .. 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}]
  63
  64    Creates and configures a new BFD peer to listen and talk to.
  65
  66    `multihop` tells the BFD daemon that we should expect packets with
  67    TTL less than 254 (because it will take more than one hop) and to
  68    listen on the multihop port (4784). When using multi-hop mode
  69    `echo-mode` will not work (see :rfc:`5883` section 3).
  70
  71    `local-address` provides a local address that we should bind our
  72    peer listener to and the address we should use to send the packets.
  73    This option is mandatory for IPv6.
  74
  75    `interface` selects which interface we should use.
  76
  77    `vrf` selects which domain we want to use.
  78
  79 .. index:: no peer <A.B.C.D|X:X::X:X>$peer [{multihop|local-address <A.B.C.D|X:X::X:X>$local|interface IFNAME$ifname|vrf NAME$vrfname}]
  80 .. clicmd:: no peer <A.B.C.D|X:X::X:X>$peer [{multihop|local-address <A.B.C.D|X:X::X:X>$local|interface IFNAME$ifname|vrf NAME$vrfname}]
  81
  82     Stops and removes the selected peer.
  83
  84 .. index:: show bfd [vrf NAME] peers [json]
  85 .. clicmd:: show bfd [vrf NAME] peers [json]
  86
  87     Show all configured BFD peers information and current status.
  88
  89 .. index:: show bfd [vrf NAME$vrfname] peer <WORD$label|<A.B.C.D|X:X::X:X>$peer [{multihop|local-address <A.B.C.D|X:X::X:X>$local|interface IFNAME$ifname}]> [json]
  90 .. clicmd:: show bfd [vrf NAME$vrfname] peer <WORD$label|<A.B.C.D|X:X::X:X>$peer [{multihop|local-address <A.B.C.D|X:X::X:X>$local|interface IFNAME$ifname}]> [json]
  91
  92     Show status for a specific BFD peer.
  93
  94
  95 .. _bfd-peer-config:
  96
  97 Peer Configurations
  98 -------------------
  99
 100 .. index:: detect-multiplier (2-255)
 101 .. clicmd:: detect-multiplier (2-255)
 102
 103    Configures the detection multiplier to determine packet loss. The
 104    remote transmission interval will be multiplied by this value to
 105    determine the connection loss detection timer. The default value is
 106    3.
 107
 108    Example: when the local system has `detect-multiplier 3` and  the
 109    remote system has `transmission interval 300`, the local system will
 110    detect failures only after 900 milliseconds without receiving
 111    packets.
 112
 113 .. index:: receive-interval (10-60000)
 114 .. clicmd:: receive-interval (10-60000)
 115
 116    Configures the minimum interval that this system is capable of
 117    receiving control packets. The default value is 300 milliseconds.
 118
 119 .. index:: transmit-interval (10-60000)
 120 .. clicmd:: transmit-interval (10-60000)
 121
 122    The minimum transmission interval (less jitter) that this system
 123    wants to use to send BFD control packets.
 124
 125 .. index:: echo-interval (10-60000)
 126 .. clicmd:: echo-interval (10-60000)
 127
 128    Configures the minimal echo receive transmission interval that this
 129    system is capable of handling.
 130
 131 .. index:: [no] echo-mode
 132 .. clicmd:: [no] echo-mode
 133
 134    Enables or disables the echo transmission mode. This mode is disabled
 135    by default.
 136
 137    It is recommended that the transmission interval of control packets
 138    to be increased after enabling echo-mode to reduce bandwidth usage.
 139    For example: `transmission-interval 2000`.
 140
 141    Echo mode is not supported on multi-hop setups (see :rfc:`5883`
 142    section 3).
 143
 144 .. index:: [no] shutdown
 145 .. clicmd:: [no] shutdown
 146
 147    Enables or disables the peer. When the peer is disabled an
 148    'administrative down' message is sent to the remote peer.
 149
 150 .. index:: label WORD
 151 .. clicmd:: label WORD
 152
 153    Labels a peer with the provided word. This word can be referenced
 154    later on other daemons to refer to a specific peer.
 155
 156
 157 .. _bfd-bgp-peer-config:
 158
 159 BGP BFD Configuration
 160 ---------------------
 161
 162 The following commands are available inside the BGP configuration node.
 163
 164 .. index:: neighbor <A.B.C.D|X:X::X:X|WORD> bfd
 165 .. clicmd:: neighbor <A.B.C.D|X:X::X:X|WORD> bfd
 166
 167    Listen for BFD events registered on the same target as this BGP
 168    neighbor. When BFD peer goes down it immediately asks BGP to shutdown
 169    the connection with its neighbor and, when it goes back up, notify
 170    BGP to try to connect to it.
 171
 172 .. index:: no neighbor <A.B.C.D|X:X::X:X|WORD> bfd
 173 .. clicmd:: no neighbor <A.B.C.D|X:X::X:X|WORD> bfd
 174
 175    Removes any notification registration for this neighbor.
 176
 177 .. index:: neighbor <A.B.C.D|X:X::X:X|WORD> bfd check-control-plane-failure
 178 .. clicmd:: neighbor <A.B.C.D|X:X::X:X|WORD> bfd check-control-plane-failure
 179
 180    Allow to write CBIT independence in BFD outgoing packets. Also allow to
 181    read both C-BIT value of BFD and lookup BGP peer status. This command is
 182    useful when a BFD down event is caught, while the BGP peer requested that
 183    local BGP keeps the remote BGP entries as staled if such issue is detected.
 184    This is the case when graceful restart is enabled, and it is wished to
 185    ignore the BD event while waiting for the remote router to restart.
 186
 187 .. index:: no neighbor <A.B.C.D|X:X::X:X|WORD> bfd check-control-plane-failure
 188 .. clicmd:: no neighbor <A.B.C.D|X:X::X:X|WORD> bfd check-control-plane-failure
 189
 190    Disallow to write CBIT independence in BFD outgoing packets. Also disallow
 191    to ignore BFD down notification. This is the default behaviour.
 192
 193 .. _bfd-ospf-peer-config:
 194
 195 OSPF BFD Configuration
 196 ----------------------
 197
 198 The following commands are available inside the interface configuration node.
 199
 200 .. index:: ip ospf bfd
 201 .. clicmd:: ip ospf bfd
 202
 203    Listen for BFD events on peers created on the interface. Every time
 204    a new neighbor is found a BFD peer is created to monitor the link
 205    status for fast convergence.
 206
 207 .. index:: no ip ospf bfd
 208 .. clicmd:: no ip ospf bfd
 209
 210    Removes any notification registration for this interface peers.
 211
 212
 213 .. _bfd-ospf6-peer-config:
 214
 215 OSPF6 BFD Configuration
 216 -----------------------
 217
 218 The following commands are available inside the interface configuration node.
 219
 220 .. index:: ipv6 ospf6 bfd
 221 .. clicmd:: ipv6 ospf6 bfd
 222
 223    Listen for BFD events on peers created on the interface. Every time
 224    a new neighbor is found a BFD peer is created to monitor the link
 225    status for fast convergence.
 226
 227 .. index:: no ipv6 ospf6 bfd
 228 .. clicmd:: no ipv6 ospf6 bfd
 229
 230    Removes any notification registration for this interface peers.
 231
 232
 233 .. _bfd-pim-peer-config:
 234
 235 PIM BFD Configuration
 236 ---------------------
 237
 238 The following commands are available inside the interface configuration node.
 239
 240 .. index:: ip pim bfd
 241 .. clicmd:: ip pim bfd
 242
 243    Listen for BFD events on peers created on the interface. Every time
 244    a new neighbor is found a BFD peer is created to monitor the link
 245    status for fast convergence.
 246
 247 .. index:: no ip pim bfd
 248 .. clicmd:: no ip pim bfd
 249
 250    Removes any notification registration for this interface peers.
 251
 252
 253 .. _bfd-configuration:
 254
 255 Configuration
 256 =============
 257
 258 Before applying ``bfdd`` rules to integrated daemons (like BGPd), we must
 259 create the corresponding peers inside the ``bfd`` configuration node.
 260
 261 Here is an example of BFD configuration:
 262
 263 ::
 264
 265     bfd
 266      peer 192.168.0.1
 267        label home-peer
 268        no shutdown
 269      !
 270     !
 271     router bgp 65530
 272      neighbor 192.168.0.1 remote-as 65531
 273      neighbor 192.168.0.1 bfd
 274      neighbor 192.168.0.2 remote-as 65530
 275      neighbor 192.168.0.2 bfd
 276      neighbor 192.168.0.3 remote-as 65532
 277      neighbor 192.168.0.3 bfd
 278     !
 279
 280 Peers can be identified by its address (use ``multihop`` when you need
 281 to specify a multi hop peer) or can be specified manually by a label.
 282
 283 Here are the available peer configurations:
 284
 285 ::
 286
 287    bfd
 288
 289     ! configure a peer on an specific interface
 290     peer 192.168.0.1 interface eth0
 291      no shutdown
 292     !
 293
 294     ! configure a multihop peer
 295     peer 192.168.0.2 multihop local-address 192.168.0.3
 296       shutdown
 297     !
 298
 299     ! configure a peer in a different vrf
 300     peer 192.168.0.3 vrf foo
 301      shutdown
 302     !
 303
 304     ! configure a peer with every option possible
 305     peer 192.168.0.4
 306      label peer-label
 307      detect-multiplier 50
 308      receive-interval 60000
 309      transmit-interval 3000
 310      shutdown
 311     !
 312
 313     ! configure a peer on an interface from a separate vrf
 314     peer 192.168.0.5 interface eth1 vrf vrf2
 315      no shutdown
 316     !
 317
 318     ! remove a peer
 319     no peer 192.168.0.3 vrf foo
 320
 321
 322 .. _bfd-status:
 323
 324 Status
 325 ======
 326
 327 You can inspect the current BFD peer status with the following commands:
 328
 329 ::
 330
 331    frr# show bfd peers
 332    BFD Peers:
 333            peer 192.168.0.1
 334                    ID: 1
 335                    Remote ID: 1
 336                    Status: up
 337                    Uptime: 1 minute(s), 51 second(s)
 338                    Diagnostics: ok
 339                    Remote diagnostics: ok
 340                    Local timers:
 341                            Receive interval: 300ms
 342                            Transmission interval: 300ms
 343                            Echo transmission interval: disabled
 344                    Remote timers:
 345                            Receive interval: 300ms
 346                            Transmission interval: 300ms
 347                            Echo transmission interval: 50ms
 348
 349            peer 192.168.1.1
 350                    label: router3-peer
 351                    ID: 2
 352                    Remote ID: 2
 353                    Status: up
 354                    Uptime: 1 minute(s), 53 second(s)
 355                    Diagnostics: ok
 356                    Remote diagnostics: ok
 357                    Local timers:
 358                            Receive interval: 300ms
 359                            Transmission interval: 300ms
 360                            Echo transmission interval: disabled
 361                    Remote timers:
 362                            Receive interval: 300ms
 363                            Transmission interval: 300ms
 364                            Echo transmission interval: 50ms
 365
 366    frr# show bfd peer 192.168.1.1
 367    BFD Peer:
 368                peer 192.168.1.1
 369                    label: router3-peer
 370                    ID: 2
 371                    Remote ID: 2
 372                    Status: up
 373                    Uptime: 3 minute(s), 4 second(s)
 374                    Diagnostics: ok
 375                    Remote diagnostics: ok
 376                    Local timers:
 377                            Receive interval: 300ms
 378                            Transmission interval: 300ms
 379                            Echo transmission interval: disabled
 380                    Remote timers:
 381                            Receive interval: 300ms
 382                            Transmission interval: 300ms
 383                            Echo transmission interval: 50ms
 384
 385    frr# show bfd peer 192.168.0.1 json
 386    {"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-interval":50,"remote-receive-interval":300,"remote-transmit-interval":300,"remote-echo-interval":50}
 387
 388
 389 You can also inspect peer session counters with the following commands:
 390
 391 ::
 392
 393    frr# show bfd peers counters
 394    BFD Peers:
 395         peer 192.168.2.1 interface r2-eth2
 396                 Control packet input: 28 packets
 397                 Control packet output: 28 packets
 398                 Echo packet input: 0 packets
 399                 Echo packet output: 0 packets
 400                 Session up events: 1
 401                 Session down events: 0
 402                 Zebra notifications: 2
 403
 404         peer 192.168.0.1
 405                 Control packet input: 54 packets
 406                 Control packet output: 103 packets
 407                 Echo packet input: 965 packets
 408                 Echo packet output: 966 packets
 409                 Session up events: 1
 410                 Session down events: 0
 411                 Zebra notifications: 4
 412
 413    frr# show bfd peer 192.168.0.1 counters
 414         peer 192.168.0.1
 415                 Control packet input: 126 packets
 416                 Control packet output: 247 packets
 417                 Echo packet input: 2409 packets
 418                 Echo packet output: 2410 packets
 419                 Session up events: 1
 420                 Session down events: 0
 421                 Zebra notifications: 4
 422
 423    frr# show bfd peer 192.168.0.1 counters json
 424    {"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}