PBR+旁挂ACG的组网方式下ACG的HA备机怎么引流

汇聚交换机上配置了根据dhcp地址做的pbr把流量引向ACG，现在想再挂一台给ACG做HA主备，但是备机的流量不知道怎么给。

这种情况下acg是不是相当于串在链路中，如果给acg升级版本的话会造成网路中断吗？现网ACG运行中备机上线后，ACG原来的配置会同步过来吗？

以下是汇聚交换机上dhcp、pbr、接口配置

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dhcp server ip-pool Wifi_internet

 vpn-instance Internet

 gateway-list 192.168.15.254

 network 192.168.12.0 mask 255.255.252.0

 dns-list 114.114.114.114 219.149.6.99

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policy-based-route from_sw permit node 1

 if-match acl 3200

 apply next-hop 192.168.253.2

 apply next-hop vpn-instance Internet 192.168.253.2

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policy-based-route to_sw permit node 1

 if-match acl 3250

 apply next-hop 192.168.253.6

 apply next-hop vpn-instance Internet 192.168.253.6

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acl advanced 3200

 rule 0 deny ip vpn-instance Internet source 192.168.15.254 0

 rule 1 deny ip vpn-instance Internet source 192.168.15.253 0

 rule 10 permit ip vpn-instance Internet source 192.168.12.0 0.0.3.255

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acl advanced 3250

 rule 0 deny ip vpn-instance Internet destination 192.168.12.254 0

 rule 1 deny ip vpn-instance Internet destination 192.168.12.253 0

 rule 10 permit ip vpn-instance Internet destination 192.168.12.0 0.0.3.255

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interface GigabitEthernet1/0/0/17

 port link-mode bridge

 description To_acg_21

 port access vlan 512

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interface GigabitEthernet1/0/0/19

 port link-mode bridge

 description To_acg_23

 port access vlan 513

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interface Vlan-interface512

 description sw-to-acg

 ip binding vpn-instance Internet

 ip address 192.168.253.1 255.255.255.252

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interface Vlan-interface513

 description acg-to-sw

 ip binding vpn-instance Internet

 ip address 192.168.253.5 255.255.255.252

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