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. This option
  76    conflicts with `vrf`.
  77
  78    `vrf` selects which domain we want to use.
  79
  80 .. 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}]
  81 .. 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}]
  82
  83     Stops and removes the selected peer.
  84
  85 .. index:: show bfd peers [json]
  86 .. clicmd:: show bfd peers [json]
  87
  88     Show all configured BFD peers information and current status.
  89
  90 .. index:: show bfd 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|vrf NAME$vrfname}]> [json]
  91 .. clicmd:: show bfd peer <WORD$label|<A.B.C.D|X:X::X:X>$peer [{multihop|local-address <A.B.C.D|X:X::X:X>$local|interface IFNAME$ifname|vrf NAME$vrfname}]> [json]
  92
  93     Show status for a specific BFD peer.
  94
  95
  96 .. _bfd-peer-config:
  97
  98 Peer Configurations
  99 -------------------
 100
 101 .. index:: detect-multiplier (2-255)
 102 .. clicmd:: detect-multiplier (2-255)
 103
 104    Configures the detection multiplier to determine packet loss. The
 105    remote transmission interval will be multiplied by this value to
 106    determine the connection loss detection timer. The default value is
 107    3.
 108
 109    Example: when the local system has `detect-multiplier 3` and  the
 110    remote system has `transmission interval 300`, the local system will
 111    detect failures only after 900 milliseconds without receiving
 112    packets.
 113
 114 .. index:: receive-interval (10-60000)
 115 .. clicmd:: receive-interval (10-60000)
 116
 117    Configures the minimum interval that this system is capable of
 118    receiving control packets. The default value is 300 milliseconds.
 119
 120 .. index:: transmit-interval (10-60000)
 121 .. clicmd:: transmit-interval (10-60000)
 122
 123    The minimum transmission interval (less jitter) that this system
 124    wants to use to send BFD control packets.
 125
 126 .. index:: echo-interval (10-60000)
 127 .. clicmd:: echo-interval (10-60000)
 128
 129    Configures the minimal echo receive transmission interval that this
 130    system is capable of handling.
 131
 132 .. index:: [no] echo-mode
 133 .. clicmd:: [no] echo-mode
 134
 135    Enables or disables the echo transmission mode. This mode is disabled
 136    by default.
 137
 138    It is recommended that the transmission interval of control packets
 139    to be increased after enabling echo-mode to reduce bandwidth usage.
 140    For example: `transmission-interval 2000`.
 141
 142    Echo mode is not supported on multi-hop setups (see :rfc:`5883`
 143    section 3).
 144
 145 .. index:: [no] shutdown
 146 .. clicmd:: [no] shutdown
 147
 148    Enables or disables the peer. When the peer is disabled an
 149    'administrative down' message is sent to the remote peer.
 150
 151 .. index:: label WORD
 152 .. clicmd:: label WORD
 153
 154    Labels a peer with the provided word. This word can be referenced
 155    later on other daemons to refer to a specific peer.
 156
 157
 158 .. _bfd-bgp-peer-config:
 159
 160 BGP BFD Configuration
 161 ---------------------
 162
 163 The following commands are available inside the BGP configuration node.
 164
 165 .. index:: neighbor <A.B.C.D|X:X::X:X|WORD> bfd
 166 .. clicmd:: neighbor <A.B.C.D|X:X::X:X|WORD> bfd
 167
 168    Listen for BFD events registered on the same target as this BGP
 169    neighbor. When BFD peer goes down it immediately asks BGP to shutdown
 170    the connection with its neighbor and, when it goes back up, notify
 171    BGP to try to connect to it.
 172
 173 .. index:: no neighbor <A.B.C.D|X:X::X:X|WORD> bfd
 174 .. clicmd:: no neighbor <A.B.C.D|X:X::X:X|WORD> bfd
 175
 176    Removes any notification registration for this neighbor.
 177
 178
 179 .. _bfd-ospf-peer-config:
 180
 181 OSPF BFD Configuration
 182 ----------------------
 183
 184 The following commands are available inside the interface configuration node.
 185
 186 .. index:: ip ospf bfd
 187 .. clicmd:: ip ospf bfd
 188
 189    Listen for BFD events on peers created on the interface. Every time
 190    a new neighbor is found a BFD peer is created to monitor the link
 191    status for fast convergence.
 192
 193 .. index:: no ip ospf bfd
 194 .. clicmd:: no ip ospf bfd
 195
 196    Removes any notification registration for this interface peers.
 197
 198
 199 .. _bfd-ospf6-peer-config:
 200
 201 OSPF6 BFD Configuration
 202 -----------------------
 203
 204 The following commands are available inside the interface configuration node.
 205
 206 .. index:: ipv6 ospf6 bfd
 207 .. clicmd:: ipv6 ospf6 bfd
 208
 209    Listen for BFD events on peers created on the interface. Every time
 210    a new neighbor is found a BFD peer is created to monitor the link
 211    status for fast convergence.
 212
 213 .. index:: no ipv6 ospf6 bfd
 214 .. clicmd:: no ipv6 ospf6 bfd
 215
 216    Removes any notification registration for this interface peers.
 217
 218
 219 .. _bfd-pim-peer-config:
 220
 221 PIM BFD Configuration
 222 ---------------------
 223
 224 The following commands are available inside the interface configuration node.
 225
 226 .. index:: ip pim bfd
 227 .. clicmd:: ip pim bfd
 228
 229    Listen for BFD events on peers created on the interface. Every time
 230    a new neighbor is found a BFD peer is created to monitor the link
 231    status for fast convergence.
 232
 233 .. index:: no ip pim bfd
 234 .. clicmd:: no ip pim bfd
 235
 236    Removes any notification registration for this interface peers.
 237
 238
 239 .. _bfd-configuration:
 240
 241 Configuration
 242 =============
 243
 244 Before applying ``bfdd`` rules to integrated daemons (like BGPd), we must
 245 create the corresponding peers inside the ``bfd`` configuration node.
 246
 247 Here is an example of BFD configuration:
 248
 249 ::
 250
 251     bfd
 252      peer 192.168.0.1
 253        label home-peer
 254        no shutdown
 255      !
 256     !
 257     router bgp 65530
 258      neighbor 192.168.0.1 remote-as 65531
 259      neighbor 192.168.0.1 bfd
 260      neighbor 192.168.0.2 remote-as 65530
 261      neighbor 192.168.0.2 bfd
 262      neighbor 192.168.0.3 remote-as 65532
 263      neighbor 192.168.0.3 bfd
 264     !
 265
 266 Peers can be identified by its address (use ``multihop`` when you need
 267 to specify a multi hop peer) or can be specified manually by a label.
 268
 269 Here are the available peer configurations:
 270
 271 ::
 272
 273    bfd
 274
 275     ! configure a peer on an specific interface
 276     peer 192.168.0.1 interface eth0
 277      no shutdown
 278     !
 279
 280     ! configure a multihop peer
 281     peer 192.168.0.2 multihop local-address 192.168.0.3
 282       shutdown
 283     !
 284
 285     ! configure a peer in a different vrf
 286     peer 192.168.0.3 vrf foo
 287      shutdown
 288     !
 289
 290     ! configure a peer with every option possible
 291     peer 192.168.0.4
 292      label peer-label
 293      detect-multiplier 50
 294      receive-interval 60000
 295      transmit-interval 3000
 296      shutdown
 297     !
 298
 299     ! remove a peer
 300     no peer 192.168.0.3 vrf foo
 301
 302
 303 .. _bfd-status:
 304
 305 Status
 306 ======
 307
 308 You can inspect the current BFD peer status with the following commands:
 309
 310 ::
 311
 312    frr# show bfd peers
 313    BFD Peers:
 314            peer 192.168.0.1
 315                    ID: 1
 316                    Remote ID: 1
 317                    Status: up
 318                    Uptime: 1 minute(s), 51 second(s)
 319                    Diagnostics: ok
 320                    Remote diagnostics: ok
 321                    Local timers:
 322                            Receive interval: 300ms
 323                            Transmission interval: 300ms
 324                            Echo transmission interval: disabled
 325                    Remote timers:
 326                            Receive interval: 300ms
 327                            Transmission interval: 300ms
 328                            Echo transmission interval: 50ms
 329
 330            peer 192.168.1.1
 331                    label: router3-peer
 332                    ID: 2
 333                    Remote ID: 2
 334                    Status: up
 335                    Uptime: 1 minute(s), 53 second(s)
 336                    Diagnostics: ok
 337                    Remote diagnostics: ok
 338                    Local timers:
 339                            Receive interval: 300ms
 340                            Transmission interval: 300ms
 341                            Echo transmission interval: disabled
 342                    Remote timers:
 343                            Receive interval: 300ms
 344                            Transmission interval: 300ms
 345                            Echo transmission interval: 50ms
 346
 347    frr# show bfd peer 192.168.1.1
 348    BFD Peer:
 349                peer 192.168.1.1
 350                    label: router3-peer
 351                    ID: 2
 352                    Remote ID: 2
 353                    Status: up
 354                    Uptime: 3 minute(s), 4 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 192.168.0.1 json
 367    {"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}
 368
 369
 370 You can also inspect peer session counters with the following commands:
 371
 372 ::
 373
 374    frr# show bfd peers counters
 375    BFD Peers:
 376         peer 192.168.2.1 interface r2-eth2
 377                 Control packet input: 28 packets
 378                 Control packet output: 28 packets
 379                 Echo packet input: 0 packets
 380                 Echo packet output: 0 packets
 381                 Session up events: 1
 382                 Session down events: 0
 383                 Zebra notifications: 2
 384
 385         peer 192.168.0.1
 386                 Control packet input: 54 packets
 387                 Control packet output: 103 packets
 388                 Echo packet input: 965 packets
 389                 Echo packet output: 966 packets
 390                 Session up events: 1
 391                 Session down events: 0
 392                 Zebra notifications: 4
 393
 394    frr# show bfd peer 192.168.0.1 counters
 395         peer 192.168.0.1
 396                 Control packet input: 126 packets
 397                 Control packet output: 247 packets
 398                 Echo packet input: 2409 packets
 399                 Echo packet output: 2410 packets
 400                 Session up events: 1
 401                 Session down events: 0
 402                 Zebra notifications: 4
 403
 404    frr# show bfd peer 192.168.0.1 counters json
 405    {"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}