BFD在两台网络设备上建立会话,用来检测网络设备间的双向转发路径,为上层应用服务。BFD本身并没有邻居发现机制,而是靠被服务的上层应用通知其邻居信息以建立会话。会话建立后会周期性地快速发送BFD报文,如果在检测时间内没有收到BFD报文则认为该双向转发路径发生了故障,通知被服务的上层应用进行相应的处理。下面以OSPF与BFD联动为例,简单介绍会话工作流程。

SW2的配置 接口配置: interface Ethernet0/0/1 port link-type access port default vlan 10 interface Ethernet0/0/2 port link-type access port default vlan 20 interface Ethernet0/0/3 port link-type trunk port trunk allow-pass vlan 2 to 4094 interface Ethernet0/0/4 port link-type trunk port trunk allow-pass vlan 2 to 4094

SW1的配置 Vlan1的地址标识的是与上层交换机连动 interface Vlanif1 ip address 192.168.1.1 255.255.255.0

interface Vlanif10 ip address 192.168.10.252 255.255.255.0 vrrp vrid 1 virtual-ip 192.168.10.254 vrrp vrid 1 priority 120 vrrp vrid 1 track bfd-session 10 reduced 30 //指定vrrp需要发送的bfd-session 10(本端标识符) //配置BFD快速收敛 Peer-ip// 对端的地址 自己的接口和自己的地址 bfd 1 bind peer-ip 192.168.1.2 interface Vlanif1 source-ip 192.168.1.1 discriminator local 10 //本地标识符 discriminator remote 100 //远端标识符。 commit interface Vlanif20 ip address 192.168.20.252 255.255.255.0 vrrp vrid 2 virtual-ip 192.168.20.254

interface MEth0/0/1

interface GigabitEthernet0/0/1 port link-type trunk port trunk allow-pass vlan 2 to 4094

SW2配置: interface Vlanif2 ip address 192.168.2.1 255.255.255.0

interface Vlanif10 ip address 192.168.10.253 255.255.255.0 vrrp vrid 1 virtual-ip 192.168.10.254

interface Vlanif20 ip address 192.168.20.253 255.255.255.0 vrrp vrid 2 virtual-ip 192.168.20.254 vrrp vrid 2 priority 120 vrrp vrid 2 track bfd-session 20 reduced 30 Vrrp需要发送与bfd本端端口标识符必须一致

interface MEth0/0/1

interface GigabitEthernet0/0/1 port link-type trunk port trunk allow-pass vlan 2 to 4094

interface GigabitEthernet0/0/2 port link-type access port default vlan 2

Peer-ip //对端的IP地址 int vlan2 //自己的接口地址与IP地址 bfd 2 bind peer-ip 192.168.2.2 interface Vlanif2 source-ip 192.168.2.1 discriminator local 20 //本端标识符 discriminator remote 101 //对端标识符 Commit

AR1配置: interface GigabitEthernet0/0/0 ip address 192.168.1.2 255.255.255.0

interface GigabitEthernet0/0/1 ip address 192.168.2.2 255.255.255.0

双向转发检测BFD peer-ip //对端的IP地址 int G0/0/0 //自己的接口与IP地址 bfd 1 bind peer-ip 192.168.1.1 interface GigabitEthernet0/0/0 source-ip 192.168.1.2 因为双点双向,所以本端标识符是BFD对等体对端标识符 对端标识符是BFD对等体的本端标识符 discriminator local 100 //本端标识符 discriminator remote 10//对端标识符 commit

双向转发检测BFD bfd 2 bind peer-ip 192.168.2.1 interface GigabitEthernet0/0/1 source-ip 192.168.2.1 discriminator local 101 //本端标识符 discriminator remote 20//对端标识符 commit