多跳检测需要三层接口来实现，不能连接二层设备。所以不需要配置缺省组播IP地址，无需指定本地出接口，只需要绑定对端IP地址和保证路由可达。

具体配置

[R1-bfd]

[R1-bfd]q

[R1]bfd r3 bind peer-ip 10.1.2.2

[R1-bfd-session-r3]discriminator local 13

[R1-bfd-session-r3]discriminator remote 31

[R1-bfd-session-r3]commit

----------

[R3]bfd

[R3-bfd]q

[R3]bfd r1 bind peer-ip 10.1.1.1

[R3-bfd-session-r1]discriminator local 31

[R3-bfd-session-r1]discriminator remote 13  

[R3-bfd-session-r1]discriminator remote 13

[R3i-bfd-session-r1]commit

=============

查看BFD状态

[R3]display bfd session all

--------------------------------------------------------------------------------

Local Remote     PeerIpAddr      State     Type        InterfaceName           

--------------------------------------------------------------------------------

31    13         10.1.1.1        Up        S_IP_PEER         -                 

--------------------------------------------------------------------------------

     Total UP/DOWN Session Number : 1/0

------------------

[R3]display bfd session all verbose

--------------------------------------------------------------------------------

Session MIndex : 256       (Multi Hop) State : Up        Name : r1             

--------------------------------------------------------------------------------

  Local Discriminator    : 31               Remote Discriminator   : 13       

  Session Detect Mode    : Asynchronous Mode Without Echo Function            

  BFD Bind Type          : Peer IP Address                                    

  Bind Session Type      : Static   

  Bind Peer IP Address   : 10.1.1.1 

  Bind Interface         : -        

  Track Interface        : -        

  FSM Board Id           : 0                TOS-EXP                : 7        

  Min Tx Interval (ms)   : 1000             Min Rx Interval (ms)   : 1000     

  Actual Tx Interval (ms): 1000             Actual Rx Interval (ms): 1000     

  Local Detect Multi     : 3                Detect Interval (ms)   : 3000     

  Echo Passive           : Disable          Acl Number             : -        

  Destination Port       : 3784             TTL                    : 254      

  Proc Interface Status  : Disable          Process PST            : Disable  

  WTR Interval (ms)      : -                Local Demand Mode      : Disable  

  Active Multi           : 3        

  Last Local Diagnostic  : No Diagnostic                                      

  Bind Application       : No Application Bind

  Session TX TmrID       : 1035             Session Detect TmrID   : 1036     

  Session Init TmrID     : -                Session WTR TmrID      : -        

  Session Echo Tx TmrID  : -        

  PDT Index              : FSM-0 | RCV-0 | IF-0 | TOKEN-0                     

  Session Description    : -        

--------------------------------------------------------------------------------

     Total UP/DOWN Session Number : 1/0

==============

配置文件

[R3]dis cu

#

sysname R3

#

bfd

#

interface GigabitEthernet0/0/3

 ip address 10.1.2.2 255.255.255.0

#

wlan

#

interface NULL0

#

bfd r1 bind peer-ip 10.1.1.1

 discriminator local 31

 discriminator remote 13

 commit

#

ip route-static 10.1.1.0 255.255.255.0 10.1.2.1

#

return

[R3]

-------------------

[R2]dis cu

#

sysname R2

#

aaa

 authentication-scheme default

 authorization-scheme default

 accounting-scheme default

 domain default

 domain default_admin

 local-user admin password cipher OOCM4m($F4ajUn1vMEIBNUw#

 local-user admin service-type http

#

firewall zone Local

 priority 16

#

interface GigabitEthernet0/0/2

 ip address 10.1.1.2 255.255.255.0

#

interface GigabitEthernet0/0/3

 ip address 10.1.2.1 255.255.255.0

#

wlan

#

interface NULL0

#

user-interface con 0

user-interface vty 0 4

user-interface vty 16 20

#

return

[R2]

-------------------

[R1]dis cu

#

sysname R1

#

bfd

#

interface GigabitEthernet0/0/2

 ip address 10.1.1.1 255.255.255.0

#

bfd r3 bind peer-ip 10.1.2.2

 discriminator local 13

 discriminator remote 31

 commit

#

ip route-static 10.1.2.0 255.255.255.0 10.1.1.2

#

return

[R1]