Administrator Guide

Troubleshooting BFD
To troubleshoot BFD, use the following commands and examples.
To control packet eld values or to examine the control packets in hexadecimal format, use the following command.
Examine control packet eld values.
CONFIGURATION mode
debug bfd detail
Examine the control packets in hexadecimal format.
CONFIGURATION
debug bfd packet
Example of Output from the debug bfd detail Command
Example of Output from the debug bfd packet Command
The following example shows a three-way handshake using the debug bfd detail command.
R1(conf-if-gi-4/24)#00:54:38: %RPM0-P:RP2 %BFDMGR-1-BFD_STATE_CHANGE: Changed session
state to
Down for neighbor 2.2.2.2 on interface Gi 4/24 (diag: 0)
00:54:38 : Sent packet for session with neighbor 2.2.2.2 on Gi 4/24
TX packet dump:
Version:1, Diag code:0, State:Down, Poll bit:0, Final bit:0, Demand bit:0
myDiscrim:4, yourDiscrim:0, minTx:1000000, minRx:1000000, multiplier:3, minEchoRx:0
00:54:38 : Received packet for session with neighbor 2.2.2.2 on Gi 4/24
RX packet dump:
Version:1, Diag code:0, State:Init, Poll bit:0, Final bit:0, Demand bit:0
myDiscrim:6, yourDiscrim:4, minTx:1000000, minRx:1000000, multiplier:3, minEchoRx:0
00:54:38: %RPM0-P:RP2 %BFDMGR-1-BFD_STATE_CHANGE: Changed session state to Up for
neighbor 2.2.2.2
on interface Gi 4/24 (diag: 0)
The following example displays hexadecimal output from the debug bfd packet command.
RX packet dump:
20 c0 03 18 00 00 00 05 00 00 00 04 00 01 86 a0
00 01 86 a0 00 00 00 00
00:34:13 : Sent packet for session with neighbor 2.2.2.2 on Gi 4/24
TX packet dump:
20 c0 03 18 00 00 00 04 00 00 00 05 00 01 86 a0
00 01 86 a0 00 00 00 00
00:34:14 : Received packet for session with neighbor 2.2.2.2 on Gi 4/24
RX packet dump:
20 c0 03 18 00 00 00 05 00 00 00 04 00 01 86 a0
00 01 86 a0 00 00 00 00
00:34:14 : Sent packet for session with neighbor 2.2.2.2 on Gi 4/24
TX packet dump:
The output for the debug bfd event command is the same as the log messages that appear on the console by default.
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Bidirectional Forwarding Detection (BFD)