可靠性配置：单臂回声 BFD 和 VRRP 联动案例

一、拓扑：

拓扑配置说明：

1. PC1 和 PC2 分属 vlan 10/20，
2. Core1/2 之间配置了 VRRP，Core1 为vlan10 网关，vrrp vrid 1 优先级120；Core2 为 vlan 20 网关，vrrp vrid 2优先级 120
3. Core1/2 上行接口分别和出口交换机Export以vlan 100/200 建立链路
4. Core1/2 和 出口交换机之间建立 ospf 邻居，宣告各自的路由
5. Core1 配置单臂回声探测到 出口交换机Export vlan100之间的链路，并在 vlan10 下的 vrrp vrid1 联动，如果到出口的 vlan 100 down，则减少优先级40，Core2 立即抢占为 vrrp master、
6. 同样，在Core2 的vlan20 vrrp vrid 2 下配置

二、主要配置命令：

Core1：

vlan batch 10 20 100 200
#
stp instance 10 root primary
stp instance 20 root secondary
#
stp region-configuration
 instance 10 vlan 10
 instance 20 vlan 20
 active region-configuration
#
bfd
#
interface Vlanif10
 ip address 10.1.1.252 255.255.255.0
 vrrp vrid 1 virtual-ip 10.1.1.254
 vrrp vrid 1 priority 120
 vrrp vrid 1 track bfd-session 1 reduced 40
#
interface Vlanif20
 ip address 10.1.2.252 255.255.255.0
 vrrp vrid 2 virtual-ip 10.1.2.254
#
interface Vlanif100
 ip address 10.1.100.2 255.255.255.252
#
interface GigabitEthernet0/0/1
 port link-type trunk
 undo port trunk allow-pass vlan 1
 port trunk allow-pass vlan 100 200
#
interface GigabitEthernet0/0/2
 port link-type trunk
 undo port trunk allow-pass vlan 1
 port trunk allow-pass vlan 10 20 100 200
#
interface GigabitEthernet0/0/3
 port link-type trunk
 port trunk allow-pass vlan 10 20
#
bfd 1 bind peer-ip 10.1.100.1 interface Vlanif100 source-ip 10.1.1.254  one-arm-
echo
 discriminator local 1
 commit
#
ospf 1 router-id 2.2.2.2
 area 0.0.0.0
  network 10.1.0.0 0.0.255.255
  network 2.2.2.2 0.0.0.0
#

开启 BFD 后，观察下 Core1 上的 bfd session

Core2：

Core2 未配置，按照 Core1 配置即可

vlan batch 10 20 100 200
#
stp instance 10 root secondary
stp instance 20 root primary
#
stp region-configuration
 instance 10 vlan 10
 instance 20 vlan 20
 active region-configuration
#
interface Vlanif10
 ip address 10.1.1.253 255.255.255.0
 vrrp vrid 1 virtual-ip 10.1.1.254
#
interface Vlanif20
 ip address 10.1.2.253 255.255.255.0
 vrrp vrid 2 virtual-ip 10.1.2.254
 vrrp vrid 2 priority 120
#
interface Vlanif200
 ip address 10.1.200.2 255.255.255.252
#
interface GigabitEthernet0/0/1
 port link-type trunk
 undo port trunk allow-pass vlan 1
 port trunk allow-pass vlan 200
#
interface GigabitEthernet0/0/2
 port link-type trunk
 undo port trunk allow-pass vlan 1
 port trunk allow-pass vlan 10 20 100 200
#
interface GigabitEthernet0/0/3
 port link-type trunk
 port trunk allow-pass vlan 10 20
#
ospf 1 router-id 3.3.3.3
 area 0.0.0.0
  network 10.1.0.0 0.0.255.255
  network 3.3.3.3 0.0.0.0
#

Export：

interface Vlanif100
 ip address 10.1.100.1 255.255.255.252
#
interface Vlanif200
 ip address 10.1.200.1 255.255.255.252
#
interface GigabitEthernet0/0/1
 port link-type trunk
 undo port trunk allow-pass vlan 1
 port trunk allow-pass vlan 100 200
#
interface GigabitEthernet0/0/2
 port link-type trunk
 undo port trunk allow-pass vlan 1
 port trunk allow-pass vlan 100 200
#
interface LoopBack1
 ip address 1.1.1.1 255.255.255.255
#
ospf 1 router-id 1.1.1.1
 area 0.0.0.0
  network 10.1.0.0 0.0.255.255
  network 1.1.1.1 0.0.0.0
#

三、检测：

把 Export 上 的 vlan 100 下 shutdown掉，观察 Core1 上的vrrp状态，原来是这样的：

现在是这样的：

而 Core2 上的 vrrp vrid1 ，则立即抢占为master，因为默认为立即抢占，延时0秒