failover双活
A/A模式HA
关键点：
1、A/A failover 利用了多模式，在不同的物理设备上active不同的虚墙以达到双活目的
2、主要在primary节点做配置，secondary节点会从primary节点同步配置，包含system和context
3、secondary节点配置任务仅包括：多模式启用、物理接口启用、failover基本配置（启用failover、指定为secondary节点、指定并命名failover lan接口，failover lan接口IP）
配置步骤
1、 准备动作：
primary节点和secondary节点都启用多模式
启用必要的物理接口
2、primary节点做failover配置
ciscoasa(config)# sh run failover
no failover
failover lan unit primary
failover lan interface fo-lan GigabitEthernet2
failover interface ip fo-lan 192.168.0.1 255.255.255.0 standby 192.168.0.2
failover group 1
preempt 60
failover group 2
secondary
preempt 60
最后，启用failover
3、在primary节点构造虚墙v1、v2，并分派虚墙关联failover组
主设备：
ciscoasa(config)# sh run context
admin-context admin
context admin
config-url disk0:/admin.cfg
!
context v1
allocate-interface GigabitEthernet0 ifinside
allocate-interface GigabitEthernet1 ifoutside
config-url disk0:/v1.cfg
join-failover-group 1
!
context v2
allocate-interface GigabitEthernet3 ifinside
allocate-interface GigabitEthernet4 ifoutside
config-url disk0:/v2.cfg
join-failover-group 2
!
4、虚墙常规配置
只在primary节点做配置，启用Failover后，secondary节点会copy该配置
changeto context v1
sh run
interface ifinside
nameif inside
security-level 100
ip address 20.0.1.1 255.255.255.0
!
interface ifoutside
nameif outside
security-level 0
ip address 5.5.5.5 255.255.255.0
!
changeto context v2
interface ifinside
nameif inside
security-level 100
ip address 30.0.1.1 255.255.255.0
!
interface ifoutside
nameif outside
security-level 0
ip address 6.6.6.6 255.255.255.0
!
5、确定primary节点failover状态正常后，配置secondary节点基本failover工作参数
failover
failover lan unit secondary
failover lan interface fo-lan GigabitEthernet2
failover interface ip fo-lan 172.16.0.1 255.255.255.0 standby 172.16.0.2
6、等待配置同步，secondary节点failover状态正常后，达到preempt阀值，secondary节点会接管group 2
