1. If secospace server of line 1 was broken, turn on emergency channel to provide the access to certificated domains.
2. If line 3 was broken and policy-based routing of the core switch were fail, it wouldn’t be diverted traffic to SACG, so that accessing to certificated domains wouldn’t be affected.
3. If line 2 was broken, and the traffic is still diverted to SACG, SACG would become a routing black hole, and all services are interrupted.