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Bidirectional Forwarding Detection (BFD)

This section provides information about using BFD with BGP and OSPF protocols on the Session Smart Networking Platform.

Overview

BFD can be enabled on the OSPF interface or the BGP neighbor. BFD configuration allows the following BFD parameters to be set:

  • enable (default: false): Enable/disable BFD protocol.
  • multiplier (default: 3): The number of BFD packets that can be lost without the BFD session declared as down.
  • required-min-rx-interval (default: 1000): The minimum interval in milliseconds that this system must receive a BFD control packet.
  • desired-tx-interval (default: 1000): The minimum transmission interval in milliseconds used to send BFD control packets.

For OSPF, the BFD configuration can be created for the given OSPF interface. Once a neighbor is learned on this interface, then a BFD session is created with the same addresses used to create the OSPF adjacency.

For BGP, the BFD configuration is created for a BGP neighbor. Once the BGP neighbor is learned, then a BGP session is created. BFD uses the same addresses as the BGP adjacency. These can be interface addresses for directly connected BGP neighbors, or loopback addresses.

The BFD peers are automatically removed by the protocols once the BGP/OSPF neighbor is removed. The OSPF/BGP adjacency remains up when BFD is configured for the peer. However, if the BFD configuration is modified while the BFD session is Up, then the OSPF/BGP adjacency will flap.

Configuration

The following is a simple configuration for OSPF and BGP.

authority
router A
routing default-instance
ospf 2
area 0.0.0.0
interface T217_DUT2 inet20
node T217_DUT2
interface inet20
bfd
enable true
required-min-rx-interval 500
desired-tx-interval 500
multiplier 3


routing-protocol bgp
neighbor 1.0.0.11
bfd
enable true
required-min-rx-interval 500
desired-tx-interval 500
multiplier 5

BFD can also be enabled in the VRF.

authority
router A
routing default-instance
vrf vrfA
ospf 2
area 0.0.0.0
interface T217_DUT2 inet30
node T217_DUT2
interface inet30
bfd
enable true
required-min-rx-interval 500
desired-tx-interval 500
multiplier 3

routing-protocol bgp
neighbor 1.0.0.11
bfd
enable true
required-min-rx-interval 500
desired-tx-interval 500
multiplier 3

Troubleshooting

The following show commands are available through the SSR PCLI. Additionally, the BFD status is available in the GUI.

The following show commands are also available for insight into the configuration:

show bfd [vrf <name>] [peer <ip>] [<verbosity>]

Example Output

# show bfd
Tue 2022-02-01 15:31:46 UTC

======= =========== ========== ======= =============
Vrf Peer Local State Uptime
======= =========== ========== ======= =============
16.0.0.3 16.0.0.2 up 15h 54m 2s
music 11.1.20.4 g20 up 37m 29s
11.1.10.4 g10 up 15h 58m 52s


# show bfd vrf music peer 11.1.20.4
Tue 2022-02-01 15:41:16 UTC

======= =========== ======= ======= ========
Vrf Peer Local State Uptime
======= =========== ======= ======= ========
music 11.1.20.4 g20 up 19s


# show bfd detail
Tue 2022-02-01 15:39:13 UTC

==========================================
Information
==========================================
Item:
Remote Detect Multiplier: 3
Remote Receive Interval: 1000
Remote: 1167833603
Vrf: default
Id: 3654638929
Receive Interval: 1000
Remote Transmit Interval: 1000
Multihop: True
Detect Multiplier: 3
Passive Mode: False
Status: up
Remote Echo Interval: 50
Local: 16.0.0.2
Remote Diagnostic: ok
Peer: 16.0.0.3
Echo Interval: 0
Uptime: 57689
Minimum Ttl: 252
Diagnostic: ok
Transmit Interval: 1000
Item:
Remote Detect Multiplier: 3
Remote: 3892773233
Interface: g20
Remote Receive Interval: 1000
Vrf: music
Id: 927933835
Receive Interval: 1000
Remote Transmit Interval: 1000
Multihop: False
Detect Multiplier: 3
Passive Mode: False
Status: up
Remote Echo Interval: 50
Remote Diagnostic: ok
Peer: 11.1.20.4
Echo Interval: 0
Uptime: 2696
Diagnostic: ok
Transmit Interval: 1000
Item:
Remote Detect Multiplier: 3
Remote: 3305953639
Interface: g10
Remote Receive Interval: 1000
Vrf: default
Id: 1713249686
Receive Interval: 1000
Remote Transmit Interval: 1000
Multihop: False
Detect Multiplier: 3
Passive Mode: False
Status: up
Remote Echo Interval: 50
Remote Diagnostic: ok
Peer: 11.1.10.4
Echo Interval: 0
Uptime: 57979
Diagnostic: ok
Transmit Interval: 1000