It surprises me how many times people invest the money in having a redundant edge, but fail to do the simple things: plug into different power sources and have their switch be a single point of failure. With this configuration, you could lose a power source, a firewall, a switch in the stack, and 75% of your cables and still function!
Configure Switch Stack:
vlan 10
name LAN
vlan 777
name ISP1
interface Port-channel1
description Primary ASA
switchport trunk allowed vlan 10,777
switchport mode trunk
!
interface Port-channel2
description Secondary ASA
switchport trunk allowed vlan 10,777
switchport mode trunk
!
interface GigabitEthernet1/0/47
description Primary ASA
switchport trunk allowed vlan 10,777
switchport mode trunk
channel-group 1 mode active
!
interface GigabitEthernet1/0/48
description Secondary ASA
switchport trunk allowed vlan 10,777
switchport mode trunk
channel-group 2 mode active
!
interface GigabitEthernet2/0/47
description Primary ASA
switchport trunk allowed vlan 10,777
switchport mode trunk
channel-group 1 mode active
!
interface GigabitEthernet2/0/48
description Secondary ASA
switchport trunk allowed vlan 10,777
switchport mode trunk
channel-group 2 mode active
!
Configuration Primary ASA:
interface GigabitEthernet0/0
channel-group 1 mode active
no nameif
no security-level
no ip address
!
interface GigabitEthernet0/1
channel-group 1 mode active
no nameif
no security-level
no ip address
!
interface Port-channel1
no nameif
no security-level
no ip address
!
interface Port-channel1.10
vlan 10
nameif LAN
security-level 100
ip address 172.17.10.10 255.255.255.0 standby 172.17.10.11
!
interface Port-channel1.777
vlan 777
nameif ISP1
security-level 0
ip address 24.222.111.25 255.255.255.240
interface GigabitEthernet0/5
description LAN/STATE Failover Interface
failover
failover lan unit primary
failover lan interface failover GigabitEthernet0/5
failover link failover GigabitEthernet0/5
failover interface ip failover 10.255.255.1 255.255.255.252 standby 10.255.255.2
monitor-interface LAN
Configure Secondary ASA:
failover
failover lan unit secondary
failover lan interface failover GigabitEthernet0/5
failover link failover GigabitEthernet0/5
failover interface ip failover 10.255.255.1 255.255.255.252 standby 10.255.255.2
monitor-interface LAN