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| -rw-r--r-- | docs/configuration/protocols/bfd.md | 397 |
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diff --git a/docs/configuration/protocols/bfd.md b/docs/configuration/protocols/bfd.md index 13623e03..656d67f8 100644 --- a/docs/configuration/protocols/bfd.md +++ b/docs/configuration/protocols/bfd.md @@ -1,205 +1,438 @@ --- -lastproofread: '2023-01-27' +myst: + html_meta: + description: | + Bidirectional Forwarding Detection (BFD) is a network protocol that + detects communication failures between two connected routing devices + in milliseconds. + keywords: bfd, bidirectional forwarding detection, bgp, ospf, isis, + multihop, echo-mode --- -```{include} /_include/need_improvement.txt -``` - (routing-bfd)= # BFD -{abbr}`BFD (Bidirectional Forwarding Detection)` is described and extended by -the following RFCs: {rfc}`5880`, {rfc}`5881` and {rfc}`5883`. +{abbr}`BFD (Bidirectional Forwarding Detection)` is a network protocol that +detects communication failures between two connected routing devices in mere +milliseconds — far faster than traditional routing protocols. +BFD does not route traffic itself. Instead, it provides rapid failure detection +for other protocols, such as {abbr}`BGP (Border Gateway Protocol)`, +{abbr}`OSPF (Open Shortest Path First)`, and static routes. -In the age of very fast networks, a second of unreachability may equal millions of lost packets. -The idea behind BFD is to detect very quickly when a peer is down and take action extremely fast. +BFD is described and extended by the following RFCs: {rfc}`5880`, {rfc}`5881` +and {rfc}`5883`. -BFD sends lots of small UDP packets very quickly to ensures that the peer is still alive. +**How BFD works** -This allows avoiding the timers defined in BGP and OSPF protocol to expires. +BFD establishes a session between two peers and exchanges rapid +{abbr}`UDP (User Datagram Protocol)` control packets at a negotiated interval +(e.g., 300 ms between consecutive packets). If a peer doesn't receive these +packets within the detection time (the negotiated interval multiplied by a +detection multiplier), BFD assumes a connection failure and notifies the +routing protocols. -## Configure BFD +## Configuration ```{cfgcmd} set protocols bfd peer \<address\> -Set BFD peer IPv4 address or IPv6 address +**Configure the IPv4 or IPv6 address of the BFD peer.** + +You can configure multiple BFD peers by specifying a different IP address +for each neighbor you want to monitor. +``` + +```{note} +For IPv6 peers, you must configure a source IP address or interface. +``` + +Example: + +```none +set protocols bfd peer 198.51.100.33 ``` ```{cfgcmd} set protocols bfd peer \<address\> echo-mode -Enables the echo transmission mode +**Enable BFD echo transmission mode for the peer at the specified IP +address.** +``` + +Example: + +```none +set protocols bfd peer 198.51.100.33 echo-mode ``` ```{cfgcmd} set protocols bfd peer \<address\> multihop -Allow this BFD peer to not be directly connected +**Configure the peer at the specified IP address as a multi-hop neighbor.** +``` + +```{note} +For BFD multi-hop peers, you must configure a local source IP address. +``` + +Example: + +```none +set protocols bfd peer 198.51.100.33 multihop +set protocols bfd peer 198.51.100.33 source address 198.51.100.1 +``` + +```{cfgcmd} set protocols bfd peer \<address\> source address \<address\> + +**Configure the source IP address for the BFD session with the peer at the +specified IP address.** +``` + +```{note} +Configuring a source IP address or interface is mandatory for IPv6 BFD +peers. +``` + +Example: + +```none +set protocols bfd peer 198.51.100.33 source address 198.51.100.1 +``` + +```{cfgcmd} set protocols bfd peer \<address\> source interface \<interface\> + +**Configure the source interface for the BFD session with the peer at the +specified IP address.** +``` + +```{note} +Configuring a source IP address or interface is mandatory for IPv6 BFD +peers. ``` -```{cfgcmd} set protocols bfd peer \<address\> source [address \<address\> | interface \<interface\>] +Example: -Bind listener to specific interface/address, mandatory for IPv6 +```none +set protocols bfd peer 2001:db8::2 source interface eth0 ``` ```{cfgcmd} set protocols bfd peer \<address\> interval echo-interval \<10-60000\> -The minimal echo receive transmission interval that this system is -capable of handling +**Configure the minimum interval, in milliseconds, at which the local system +can receive echo packets from the peer at the specified IP address.** +``` + +Example: + +```none +set protocols bfd peer 198.51.100.33 interval echo-interval 50 ``` ```{cfgcmd} set protocols bfd peer \<address\> interval multiplier \<2-255\> -Remote transmission interval will be multiplied by this value +**Configure the detection multiplier for the peer at the specified IP +address.** + +BFD multiplies the negotiated interval by this value to calculate the +detection time — the period after which it declares the session down if no +control packets arrive. +``` + +Example: + +```none +set protocols bfd peer 192.0.2.1 interval multiplier 3 +``` + +```{cfgcmd} set protocols bfd peer \<address\> interval receive \<10-60000\> + +**Configure the interval, in milliseconds, at which the local system can +receive BFD control packets from the peer at the specified IP address.** ``` -```{cfgcmd} set protocols bfd peer \<address\> interval [receive | transmit] \<10-60000\> +Example: -Interval in milliseconds +```none +set protocols bfd peer 192.0.2.1 interval receive 300 +``` + +```{cfgcmd} set protocols bfd peer \<address\> interval transmit \<10-60000\> + +**Configure the interval, in milliseconds, at which you want the local +system to transmit BFD control packets to the peer at the specified IP +address.** +``` + +Example: + +```none +set protocols bfd peer 192.0.2.1 interval transmit 300 ``` ```{cfgcmd} set protocols bfd peer \<address\> shutdown -Disable a BFD peer +**Disable the BFD session with the peer at the specified IP address.** +``` + +Example: + +```none +set protocols bfd peer 198.51.100.33 shutdown ``` ```{cfgcmd} set protocols bfd peer \<address\> minimum-ttl \<1-254\> -For multi hop sessions only. Configure the minimum expected TTL for an -incoming BFD control packet. +**Configure the minimum {abbr}`TTL (Time to Live)` value that incoming BFD +control packets must have to be accepted from the peer at the specified IP +address.** + +BFD discards any packet whose TTL is below this threshold. +``` + +```{note} +This setting applies only to multi-hop sessions. +``` + +Example: + +```none +set protocols bfd peer 192.0.2.1 minimum-ttl 250 +``` + +```{cfgcmd} set protocols bfd peer \<address\> passive + +**Configure the BFD session with the peer at the specified IP address to +operate in passive mode.** + +In passive mode, the local system does not initiate the BFD session. +Instead, it waits to receive the first BFD control packet from the remote +peer. +``` + +```{note} +At least one of the two peers must remain in active mode for the session +to establish. If both peers are passive, neither will initiate, and the +session never establishes. +``` + +Example: + +```none +set protocols bfd peer 198.51.100.33 passive +``` + +```{cfgcmd} set protocols bfd peer \<address\> profile \<profile\> -This feature serves the purpose of thightening the packet validation -requirements to avoid receiving BFD control packets from other sessions. +**Apply settings from a designated BFD profile to the peer at the specified +IP address.** +``` + +Example: + +```none +set protocols bfd peer 192.0.2.1 profile datacenter-fast +``` + +```{cfgcmd} set protocols bfd peer \<address\> vrf \<vrf\> + +**Bind the BFD session with the peer at the specified IP address to a +specific {abbr}`VRF (Virtual Routing and Forwarding)` instance.** +``` + +Example: + +```none +set protocols bfd peer 192.0.2.1 vrf customer-a ``` ### Enable BFD in BGP ```{cfgcmd} set protocols bgp neighbor \<neighbor\> bfd -Enable BFD on a single BGP neighbor +**Enable BFD failure detection for the BGP session with the neighbor at the +specified IP address.** +``` + +Example: + +```none +set protocols bgp neighbor 192.0.2.1 bfd ``` ```{cfgcmd} set protocols bgp peer-group \<neighbor\> bfd -Enable BFD on a BGP peer group +**Enable BFD failure detection for all neighbors in the specified BGP peer +group.** +``` + +Example: + +```none +set protocols bgp peer-group INTERNAL-PEERS bfd ``` ### Enable BFD in OSPF ```{cfgcmd} set protocols ospf interface \<interface\> bfd - Enable BFD for OSPF on an interface +**Enable BFD failure detection for OSPF neighbors discovered on the specified +interface.** +When OSPF forms an adjacency with a neighbor on this interface, it requests +BFD to establish a session with that neighbor. +``` + +Example: + +```none +set protocols ospf interface eth0 bfd ``` ```{cfgcmd} set protocols ospfv3 interface \<interface\> bfd -Enable BFD for OSPFv3 on an interface +**Enable BFD failure detection for OSPFv3 neighbors discovered on the +specified interface.** + +When OSPFv3 forms an adjacency with a neighbor on this interface, it +requests BFD to establish a session with that neighbor. ``` -### Enable BFD in ISIS +Example: -```{cfgcmd} set protocols isis \<name\> interface \<interface\> bfd +```none +set protocols ospfv3 interface eth0 bfd +``` -Enable BFD for ISIS on an interface +### Enable BFD in IS-IS +```{cfgcmd} set protocols isis interface \<interface\> bfd + +**Enable BFD failure detection for IS-IS neighbors discovered on the +specified interface.** + +When IS-IS forms an adjacency with a neighbor on this interface, it requests +BFD to establish a session with that neighbor. +``` + +Example: + +```none +set protocols isis interface eth0 bfd ``` -## Operational Commands +## Operation ```{opcmd} show bfd peers - Show all BFD peers +**Show all BFD peers.** +``` - :::{code-block} none - BFD Peers: - peer 198.51.100.33 vrf default interface eth4.100 +```none +vyos@vyos:~$ show bfd peers +BFD Peers: + peer 198.51.100.33 vrf default ID: 4182341893 - Remote ID: 12678929647 + Remote ID: 3267892964 + Active mode Status: up Uptime: 1 month(s), 16 hour(s), 29 minute(s), 38 second(s) Diagnostics: ok Remote diagnostics: ok + Peer Type: configured + RTT min/avg/max: 245/267/289 usec Local timers: + Detect-multiplier: 3 Receive interval: 300ms Transmission interval: 300ms - Echo transmission interval: 50ms + Echo receive interval: 50ms + Echo transmission interval: disabled Remote timers: + Detect-multiplier: 3 Receive interval: 300ms Transmission interval: 300ms - Echo transmission interval: 0ms + Echo receive interval: disabled - peer 198.51.100.55 vrf default interface eth4.101 - ID: 4618932327 + peer 198.51.100.55 multihop local-address 198.51.100.1 vrf default + ID: 3618932327 Remote ID: 3312345688 + Active mode + Minimum TTL: 254 Status: up Uptime: 20 hour(s), 16 minute(s), 19 second(s) Diagnostics: ok Remote diagnostics: ok + Peer Type: configured + RTT min/avg/max: 1240/1289/1356 usec Local timers: + Detect-multiplier: 3 Receive interval: 300ms Transmission interval: 300ms - Echo transmission interval: 50ms + Echo receive interval: 50ms + Echo transmission interval: disabled Remote timers: - Receive interval: 300ms - Transmission interval: 300ms - Echo transmission interval: 0ms - ::: + Detect-multiplier: 3 + Receive interval: 1000ms + Transmission interval: 1000ms + Echo receive interval: disabled ``` -## BFD Static Route Monitoring +## BFD static route monitoring +A monitored static route is present in the +{abbr}`RIB (Routing Information Base)` only when the BFD session is up. If +the session goes down, the route is removed. -A monitored static route conditions the installation to the RIB on the BFD -session running state: when BFD session is up the route is installed to RIB, -but when the BFD session is down it is removed from the RIB. +```{cfgcmd} set protocols static route \<subnet\> next-hop \<address\> bfd profile \<profile\> +**Configure BFD failure detection for a single-hop static route.** -### Configuration +BFD uses the next-hop IP address as the BFD peer IP address and applies +settings from the specified BFD profile. +``` -```{cfgcmd} set protocols static route \<subnet\> next-hop \<address\> bfd profile \<profile\> +Example: -Configure a static route for \<subnet\> using gateway \<address\> -and use the gateway address as BFD peer destination address. +```none +set protocols static route 10.0.0.0/24 next-hop 192.0.2.1 bfd profile datacenter-fast ``` -```{cfgcmd} set protocols static route \<subnet\> next-hop \<address\> bfd multi-hop source \<address\> profile \<profile\> +```{cfgcmd} set protocols static route \<subnet\> next-hop \<address\> bfd multi-hop source-address \<address\> + +**Configure BFD failure detection for a multi-hop static route.** -Configure a static route for \<subnet\> using gateway \<address\>, -use source address to identify the peer when is multi-hop session -and the gateway address as BFD peer destination address. +BFD uses the next-hop IP address as the BFD peer IP address and the +multi-hop source IP address as the local source IP for outgoing BFD packets. ``` -```{cfgcmd} set protocols static route6 \<subnet\> next-hop \<address\> bfd profile \<profile\> +Example: -Configure a static route for \<subnet\> using gateway \<address\> -and use the gateway address as BFD peer destination address. +```none +set protocols static route 10.0.0.0/24 next-hop 198.51.100.33 bfd multi-hop source-address 198.51.100.1 ``` -```{cfgcmd} set protocols static route6 \<subnet\> next-hop \<address\> bfd multi-hop source \<address\> profile \<profile\> +```{cfgcmd} set protocols static route6 \<subnet\> next-hop \<address\> bfd profile \<profile\> -Configure a static route for \<subnet\> using gateway \<address\>, -use source address to identify the peer when is multi-hop session -and the gateway address as BFD peer destination address. -``` +**Configure BFD failure detection for a single-hop IPv6 static route.** -(bfd-operational-commands)= +BFD uses the next-hop IPv6 address as the BFD peer IPv6 address and applies +settings from the specified BFD profile. +``` -## Operational Commands +Example: -```{opcmd} show bfd static routes +```none +set protocols static route6 2001:db8:1::/64 next-hop 2001:db8::1 bfd profile datacenter-fast +``` -Showing BFD monitored static routes +```{cfgcmd} set protocols static route6 \<subnet\> next-hop \<address\> bfd multi-hop source-address \<address\> -:::{code-block} none -Showing BFD monitored static routes: +**Configure BFD failure detection for a multi-hop IPv6 static route.** - Next hops: - VRF default IPv4 Unicast: - 10.10.13.3/32 peer 192.168.2.3 (status: installed) - 172.16.10.3/32 peer 192.168.10.1 (status: uninstalled) +BFD uses the next-hop IPv6 address as the BFD peer IPv6 address and the +multi-hop source IPv6 address as the local source IPv6 address for outgoing +BFD packets. +``` - VRF default IPv4 Multicast: +Example: - VRF default IPv6 Unicast: -::: -```
\ No newline at end of file +```none +set protocols static route6 2001:db8:1::/64 next-hop 2001:db8:100::33 bfd multi-hop source-address 2001:db8::1 +``` |