RouterA设置
该路由器就是个e-trunk的伙伴，只是普通的eth-trunk，还配置延时回切
interface Eth-Trunk1
portswitch
mode lacp-static
lacp preempt enable
lacp preempt delay 20
接口
interface GigabitEthernet0/1/1
eth-trunk 1
lacp priority 150
RouterB设置
路由器B的普通eth-trunk和e-trunk绑定起来，而且还配置路由器B和路由器C的bfd检测，出了故障丢包少点，当然e-trunk可以决定路由器B和路由器C的主备关系。
interface Eth-Trunk10
portswitch
port link-type trunk
port trunk allow-pass vlan 1 to 2
mode lacp-static
e-trunk 1
e-trunk 1
peer-address 192.168.1.2 source-address 192.168.1.1
e-trunk track bfd-session session-name hello
