[R1]
{INTERFACE}
interface Ethernet0/0
ip address 10.99.1.1 255.255.255.0
ip ospf bfd
bfd interval 100 min_rx 100 multiplier 3
{OSPF}
router ospf 1
router-id 1.1.1.1
passive-interface default
no passive-interface Ethernet0/0
no passive-interface Ethernet0/1
network 10.1.1.1 0.0.0.0 area 0
network 10.1.2.1 0.0.0.0 area 0
network 10.1.3.1 0.0.0.0 area 0
network 10.99.1.1 0.0.0.0 area 0
network 10.99.2.1 0.0.0.0 area 0
bfd all-interfaces
[R2]
{INTERFACE}
interface Ethernet0/0
ip address 10.99.1.2 255.255.255.0
ip ospf bfd
bfd interval 100 min_rx 100 multiplier 3
{OSPF}
router ospf 1
router-id 2.2.2.2
passive-interface default
no passive-interface Ethernet0/0
network 10.2.1.2 0.0.0.0 area 2
network 10.2.2.2 0.0.0.0 area 2
network 10.2.3.2 0.0.0.0 area 2
network 10.99.1.2 0.0.0.0 area 0
bfd all-interfaces
{SHOW COMMANDS AND DEBUG}
R1#show bfd ?
drops Display packets dropped
map BFD map entry DB
neighbors BFD neighbors
summary BFD summary
R1#show bfd neighbors ?
client View neighbors of a specific client
details Display all BFD parameters
hardware Display hardware offloaded sessions
inactive Display inactive adjs
ipv4 Neighbor IPv4 single-hop address
ipv6 Neighbor IPv6 single-hop address
mpls-pw MPLS Pseudo-wire
mpls-tp MPLS TP
multihop-ipv4 Multi-hop IPv4
multihop-ipv6 Multi-hop IPv6
vrf Show entries for a VPN Routing/Forwarding instance
| Output modifiers
<cr>
R1#show bfd summary
Session Up Down
Total 1 1 0
R1#show bfd neighbors
IPv4 Sessions
NeighAddr LD/RD RH/RS State Int
10.99.1.2 1/1 Up Up Et0/0
R1#show bfd neighbors details
IPv4 Sessions
NeighAddr LD/RD RH/RS State Int
10.99.1.2 1/1 Up Up Et0/0
Session state is UP and using echo function with 100 ms interval.
Session Host: Software
OurAddr: 10.99.1.1
Handle: 1
Local Diag: 0, Demand mode: 0, Poll bit: 0
MinTxInt: 1000000, MinRxInt: 1000000, Multiplier: 3
Received MinRxInt: 1000000, Received Multiplier: 3
Holddown (hits): 0(0), Hello (hits): 1000(503)
Rx Count: 502, Rx Interval (ms) min/max/avg: 1/1077/882 last: 896 ms ago
Tx Count: 505, Tx Interval (ms) min/max/avg: 1/1042/878 last: 173 ms ago
Elapsed time watermarks: 0 0 (last: 0)
Registered protocols: OSPF
Uptime: 00:07:22
Last packet: Version: 1 - Diagnostic: 0
State bit: Up - Demand bit: 0
Poll bit: 0 - Final bit: 0
C bit: 0
Multiplier: 3 - Length: 24
My Discr.: 1 - Your Discr.: 1
Min tx interval: 1000000 - Min rx interval: 1000000
Min Echo interval: 100000
R1#show bfd drops
BFD Drop Statistics
IPV4 IPV6 IPV4-M IPV6-M MPLS_PW MPLS_TP_LSP
Invalid TTL 0 0 0 0 0 0
BFD Not Configured 0 0 0 0 0 0
No BFD Adjacency 0 0 0 0 0 0
Invalid Header Bits 0 0 0 0 0 0
Invalid Discriminator 0 0 0 0 0 0
Session AdminDown 0 0 0 0 0 0
Authen invalid BFD ver 0 0 0 0 0 0
Authen invalid len 0 0 0 0 0 0
Authen invalid seq 0 0 0 0 0 0
Authen failed 0 0 0 0 0 0
{Debug BFD}
R2(config)#in ethernet 0/0
R2(config-if)#shutdown
R2(config-if)#no shutdown
R1#debug bfd event
*Jun 24 06:37:47.063: BFD-DEBUG Event: V1 FSM ld:1 handle:1 event:ECHO FAILURE state:UP (0)
*Jun 24 06:37:47.064: BFD-DEBUG EVENT: bfd_session_destroyed, proc:OSPF, handle:1 act
*Jun 24 06:37:47.064: %OSPF-5-ADJCHG: Process 1, Nbr 2.2.2.2 on Ethernet0/0 from FULL to DOWN, Neighbor Down: BFD node down
*Jun 24 06:37:47.065: BFD-DEBUG Event: notify client(OSPF) IP:10.99.1.2, ld:1, handle:1, event:1, cp independent failure (0)
*Jun 24 06:37:47.065: BFD-DEBUG Event: V1 FSM ld:1 handle:1 event:Session delete state:DOWN (0)
*Jun 24 06:37:50.067: BFD-DEBUG Event: V1 FSM ld:1 handle:1 event:DETECT TIMER EXPIRED state:ADMIN DOWN (0)
*Jun 24 06:37:50.067: BFD-DEBUG Event: decreasing credits by 12 [to 0] (0)
*Jun 24 06:37:52.789: %OSPF-5-ADJCHG: Process 1, Nbr 2.2.2.2 on Ethernet0/0 from LOADING to FULL, Loading Done
*Jun 24 06:37:52.808: BFD-DEBUG EVENT: bfd_session_created, proc:OSPF, idb:Ethernet0/0 handle:1 act
*Jun 24 06:37:53.627: BFD-DEBUG Event: V1 FSM ld:1 handle:1 event:RX DOWN state:DOWN (0)
*Jun 24 06:37:53.628: BFD-DEBUG Event: V1 FSM ld:1 handle:1 event:RX UP state:INIT (0)
*Jun 24 06:37:53.628: BFD-DEBUG Event: notify client(OSPF) IP:10.99.1.2, ld:1, handle:1, event:0, (0)
R2(config)#router ospf 1
R2(config-router)#no network 10.99.1.2 0.0.0.0 area 0
*Jun 24 06:42:08.307: BFD-DEBUG Event: V1 FSM ld:1 handle:1 event:RX ADMINDOWN state:UP (0)
*Jun 24 06:42:08.308: BFD-DEBUG Event: notify client(OSPF) IP:10.99.1.2, ld:1, handle:1, event:1 adminDown, (0)
*Jun 24 06:42:09.137: BFD-DEBUG Event: V1 FSM ld:1 handle:1 event:RX ADMINDOWN state:DOWN (0)
*Jun 24 06:42:10.107: BFD-DEBUG Event: V1 FSM ld:1 handle:1 event:RX ADMINDOWN state:DOWN (0)
*Jun 24 06:42:10.968: BFD-DEBUG Event: V1 FSM ld:1 handle:1 event:RX ADMINDOWN state:DOWN (0)
*Jun 24 06:42:45.805: %OSPF-5-ADJCHG: Process 1, Nbr 2.2.2.2 on Ethernet0/0 from FULL to DOWN, Neighbor Down: Dead timer expired
*Jun 24 06:42:45.805: BFD-DEBUG EVENT: bfd_session_destroyed, proc:OSPF, handle:1 act
*Jun 24 06:42:45.806: BFD-DEBUG Event: decreasing credits by 12 [to 0] (0)
R2(config-router)#network 10.99.1.2 0.0.0.0 area 0
*Jun 24 06:44:20.170: %OSPF-5-ADJCHG: Process 1, Nbr 2.2.2.2 on Ethernet0/0 from LOADING to FULL, Loading Done
*Jun 24 06:44:20.183: BFD-DEBUG EVENT: bfd_session_created, proc:OSPF, idb:Ethernet0/0 handle:1 act
*Jun 24 06:44:21.077: BFD-DEBUG Event: V1 FSM ld:1 handle:1 event:RX DOWN state:DOWN (0)
*Jun 24 06:44:21.077: BFD-DEBUG Event: V1 FSM ld:1 handle:1 event:RX UP state:INIT (0)
*Jun 24 06:44:21.077: BFD-DEBUG Event: notify client(OSPF) IP:10.99.1.2, ld:1, handle:1, event:0, (0)
R2(config)#interface ethernet 0/0
R2(config-if)#shutdown
R2(config-if)#no shutdown
R1#debug bfd packet
*Jun 24 13:10:15.049: %OSPF-5-ADJCHG: Process 1, Nbr 2.2.2.2 on Ethernet0/0 from FULL to DOWN, Neighbor Down: BFD node down
*Jun 24 13:10:15.050: BFD-DEBUG Packet: Tx IP:10.99.1.2 ld/rd:1/0 diag:2(Echo Function Failed) Down cnt:1787 (0)
*Jun 24 13:10:15.054: BFD-DEBUG Packet: Tx IP:10.99.1.2 ld/rd:1/0 diag:7(Administratively Down) AdminDown cnt:1788 (0)
*Jun 24 13:10:56.535: %OSPF-5-ADJCHG: Process 1, Nbr 2.2.2.2 on Ethernet0/0 from LOADING to FULL, Loading Done
*Jun 24 13:10:57.381: BFD-DEBUG Packet: Rx IP:10.99.1.2 ld/rd:1/1 diag:0(No Diagnostic) Init cnt:1 ttl:254 (0)
*Jun 24 13:10:57.381: BFD-DEBUG Packet: Tx IP:10.99.1.2 ld/rd:1/1 diag:0(No Diagnostic) Up cnt:2 (0)
*Jun 24 13:10:57.381: BFD-DEBUG Packet: Rx IP:10.99.1.2 ld/rd:1/1 diag:0(No Diagnostic) Up cnt:2 ttl:254 (0)
R1#show bfd drops
BFD Drop Statistics
IPV4 IPV6 IPV4-M IPV6-M MPLS_PW MPLS_TP_LSP
Invalid TTL 0 0 0 0 0 0
BFD Not Configured 0 0 0 0 0 0
No BFD Adjacency 0 0 0 0 0 0
Invalid Header Bits 0 0 0 0 0 0
Invalid Discriminator 0 0 0 0 0 0
Session AdminDown 2 0 0 0 0 0
Authen invalid BFD ver 0 0 0 0 0 0
Authen invalid len 0 0 0 0 0 0
Authen invalid seq 0 0 0 0 0 0
Authen failed 0 0 0 0 0 0
R1#show clock
*10:55:17.078 UTC Wed Jun 24 2015
R1#show interfaces ethernet 0/0 stats
Ethernet0/0
Switching path Pkts In Chars In Pkts Out Chars Out
Processor 528 248328 787 264600
Route cache 52560 2869584 52570 2870208
Total 53088 3117912 53357 3134808
R1#show clock
*10:55:44.779 UTC Wed Jun 24 2015
R1#show interfaces ethernet 0/0 stats
Ethernet0/0
Switching path Pkts In Chars In Pkts Out Chars Out
Processor 532 248962 794 265414
Route cache 53178 2903340 53187 2903898
Total 53710 3152302 53981 3169312
R1#show processes cpu sorted | in BFD
221 5448 286802 18 1.91% 1.94% 1.93% 0 BFD IOU Process
130 8 1346 5 0.00% 0.00% 0.00% 0 BFD
187 0 3 0 0.00% 0.00% 0.00% 0 BFD events
208 0 5 0 0.00% 0.00% 0.00% 0 BFD debugs
254 8 408 19 0.00% 0.00% 0.00% 0 BFD packet stats
- BFD is always unicast.
- BFD control packets are always UDP, sourced from 49152 and sent to 3784. BFD echo packets are also UDP, and are sourced from 3785 and sent to 3785 (why this is will become obvious later).
BFD Single-Hop Authentication here
If you wish to take a look at the Cisco BFD Configuration Guide, it can be found here.
