Customer has ASA 5520 pairs in Active/Standby configuration. The firewalls are physically across campus from each other. The outside interfaces are connected into the same VLAN (Cisco enterprise switches). Upstream is a pair of Juniper routers using a virtual gateway address (VRRP).
The environment was stable for over a year until the customer made some changes to the switched environment (not totally sure what changed).
Basically when I bring the secondary firewall back online, the Internet access goes down or they experience flaky Internet behavior (slow downs). When I disable the switch interface connected to the secondary ASA outside interface, the Internet access is still unavailable unless I reboot the primary.
So there seems to be confusion on the outside LAN segment (ARP issues, interface issues, switch issues, VRRP, etc).
I tried hard coding the primary/secondary mac addresses, but that didn't seem to help.
Sorry for the lack of detail, but just looking for some general troubleshooting ideas.