:abbr:`BFD (Bidirectional Forwarding Detection)` stands for Bidirectional Forwarding Detection and it is described and extended by the following RFCs:
Currently, there are two implementations of the BFD commands in FRR:
- :abbr:`PTM (Prescriptive Topology Manager)`: an external daemon which implements BFD;
bfdd: a BFD implementation that is able to talk with remote peers;
This document will focus on the later implementation: bfdd.
bfdd default configuration file is :file:`bfdd.conf`. bfdd searches the current directory first then |INSTALL_PREFIX_ETC|/bfdd.conf. All of bfdd's command must be configured in :file:`bfdd.conf`.
bfdd specific invocation options are described below. Common options may also be specified (:ref:`common-invocation-options`).
.. program:: bfdd
.. option:: --bfdctl <unix-socket>
Set the BFD daemon control socket location. If using a non-default
socket location::
/usr/lib/frr/bfdd --bfdctl /tmp/bfdd.sock
The default UNIX socket location is:
#define BFDD_CONTROL_SOCKET "|INSTALL_PREFIX_STATE|/bfdd.sock"
.. index:: bfd
.. clicmd:: bfd Opens the BFD daemon configuration node.
.. 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}]
.. 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}]
Creates and configures a new BFD peer to listen and talk to.
`multihop` tells the BFD daemon that we should expect packets with
TTL less than 254 (because it will take more than one hop) and to
listen on the multihop port (4784). When using multi-hop mode
`echo-mode` will not work (see :rfc:`5883` section 3).
`local-address` provides a local address that we should bind our
peer listener to and the address we should use to send the packets.
This option is mandatory for IPv6.
`interface` selects which interface we should use. This option
conflicts with `vrf`.
`vrf` selects which domain we want to use.
.. 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}]
.. 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}]
Stops and removes the selected peer.
.. index:: show bfd peers [json]
.. clicmd:: show bfd peers [json]
Show all configured BFD peers information and current status.
.. 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$vrfname}]> [json]
.. clicmd:: show bfd peer <WORD$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]
Show status for a specific BFD peer.
.. index:: detect-multiplier (2-255)
.. clicmd:: detect-multiplier (2-255) Configures the detection multiplier to determine packet loss. The remote transmission interval will be multiplied by this value to determine the connection loss detection timer. The default value is 3. Example: when the local system has `detect-multiplier 3` and the remote system has `transmission interval 300`, the local system will detect failures only after 900 milliseconds without receiving packets.
.. index:: receive-interval (10-60000)
.. clicmd:: receive-interval (10-60000) Configures the minimum interval that this system is capable of receiving control packets. The default value is 300 milliseconds.
.. index:: transmit-interval (10-60000)
.. clicmd:: transmit-interval (10-60000) The minimum transmission interval (less jitter) that this system wants to use to send BFD control packets.
.. index:: echo-interval (10-60000)
.. clicmd:: echo-interval (10-60000) Configures the minimal echo receive transmission interval that this system is capable of handling.
.. index:: [no] echo-mode
.. clicmd:: [no] echo-mode Enables or disables the echo transmission mode. This mode is disabled by default. It is recommended that the transmission interval of control packets to be increased after enabling echo-mode to reduce bandwidth usage. For example: `transmission-interval 2000`. Echo mode is not supported on multi-hop setups (see :rfc:`5883` section 3).
.. index:: [no] shutdown
.. clicmd:: [no] shutdown Enables or disables the peer. When the peer is disabled an 'administrative down' message is sent to the remote peer.
.. index:: label WORD
.. clicmd:: label WORD Labels a peer with the provided word. This word can be referenced later on other daemons to refer to a specific peer.
The following commands are available inside the BGP configuration node.
.. index:: neighbor <A.B.C.D|X:X::X:X|WORD> bfd
.. clicmd:: neighbor <A.B.C.D|X:X::X:X|WORD> bfd Listen for BFD events registered on the same target as this BGP neighbor. When BFD peer goes down it immediately asks BGP to shutdown the connection with its neighbor and, when it goes back up, notify BGP to try to connect to it.
.. index:: no neighbor <A.B.C.D|X:X::X:X|WORD> bfd
.. clicmd:: no neighbor <A.B.C.D|X:X::X:X|WORD> bfd Removes any notification registration for this neighbor.
The following commands are available inside the interface configuration node.
.. index:: ip ospf bfd
.. clicmd:: ip ospf bfd Listen for BFD events on peers created on the interface. Every time a new neighbor is found a BFD peer is created to monitor the link status for fast convergence.
.. index:: no ip ospf bfd
.. clicmd:: no ip ospf bfd Removes any notification registration for this interface peers.
The following commands are available inside the interface configuration node.
.. index:: ipv6 ospf6 bfd
.. clicmd:: ipv6 ospf6 bfd Listen for BFD events on peers created on the interface. Every time a new neighbor is found a BFD peer is created to monitor the link status for fast convergence.
.. index:: no ipv6 ospf6 bfd
.. clicmd:: no ipv6 ospf6 bfd Removes any notification registration for this interface peers.
The following commands are available inside the interface configuration node.
.. index:: ip pim bfd
.. clicmd:: ip pim bfd Listen for BFD events on peers created on the interface. Every time a new neighbor is found a BFD peer is created to monitor the link status for fast convergence.
.. index:: no ip pim bfd
.. clicmd:: no ip pim bfd Removes any notification registration for this interface peers.
Before applying bfdd rules to integrated daemons (like BGPd), we must
create the corresponding peers inside the bfd configuration node.
Here is an example of BFD configuration:
bfd peer 192.168.0.1 label home-peer no shutdown ! ! router bgp 65530 neighbor 192.168.0.1 remote-as 65531 neighbor 192.168.0.1 bfd neighbor 192.168.0.2 remote-as 65530 neighbor 192.168.0.2 bfd neighbor 192.168.0.3 remote-as 65532 neighbor 192.168.0.3 bfd !
Peers can be identified by its address (use multihop when you need
to specify a multi hop peer) or can be specified manually by a label.
Here are the available peer configurations:
bfd ! configure a peer on an specific interface peer 192.168.0.1 interface eth0 no shutdown ! ! configure a multihop peer peer 192.168.0.2 multihop local-address 192.168.0.3 shutdown ! ! configure a peer in a different vrf peer 192.168.0.3 vrf foo shutdown ! ! configure a peer with every option possible peer 192.168.0.4 label peer-label detect-multiplier 50 receive-interval 60000 transmit-interval 3000 shutdown ! ! remove a peer no peer 192.168.0.3 vrf foo
You can inspect the current BFD peer status with the following commands:
frr# show bfd peers
BFD Peers:
peer 192.168.0.1
ID: 1
Remote ID: 1
Status: up
Uptime: 1 minute(s), 51 second(s)
Diagnostics: ok
Remote diagnostics: ok
Local timers:
Receive interval: 300ms
Transmission interval: 300ms
Echo transmission interval: disabled
Remote timers:
Receive interval: 300ms
Transmission interval: 300ms
Echo transmission interval: 50ms
peer 192.168.1.1
label: router3-peer
ID: 2
Remote ID: 2
Status: up
Uptime: 1 minute(s), 53 second(s)
Diagnostics: ok
Remote diagnostics: ok
Local timers:
Receive interval: 300ms
Transmission interval: 300ms
Echo transmission interval: disabled
Remote timers:
Receive interval: 300ms
Transmission interval: 300ms
Echo transmission interval: 50ms
frr# show bfd peer 192.168.1.1
BFD Peer:
peer 192.168.1.1
label: router3-peer
ID: 2
Remote ID: 2
Status: up
Uptime: 3 minute(s), 4 second(s)
Diagnostics: ok
Remote diagnostics: ok
Local timers:
Receive interval: 300ms
Transmission interval: 300ms
Echo transmission interval: disabled
Remote timers:
Receive interval: 300ms
Transmission interval: 300ms
Echo transmission interval: 50ms
frr# show bfd peer 192.168.0.1 json
{"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}
You can also inspect peer session counters with the following commands:
frr# show bfd peers counters
BFD Peers:
peer 192.168.2.1 interface r2-eth2
Control packet input: 28 packets
Control packet output: 28 packets
Echo packet input: 0 packets
Echo packet output: 0 packets
Session up events: 1
Session down events: 0
Zebra notifications: 2
peer 192.168.0.1
Control packet input: 54 packets
Control packet output: 103 packets
Echo packet input: 965 packets
Echo packet output: 966 packets
Session up events: 1
Session down events: 0
Zebra notifications: 4
frr# show bfd peer 192.168.0.1 counters
peer 192.168.0.1
Control packet input: 126 packets
Control packet output: 247 packets
Echo packet input: 2409 packets
Echo packet output: 2410 packets
Session up events: 1
Session down events: 0
Zebra notifications: 4
frr# show bfd peer 192.168.0.1 counters json
{"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}