Troubleshooting BFD
To troubleshoot BFD, use the following commands and examples.
To control packet field values or to examine the control packets in hexadecimal format, use the following
command.
• Examine control packet field 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.
174 Bidirectional Forwarding Detection (BFD)