Additional Thoughts About Security Levels

It is common to see customers ask a question about the need and importance of associating security levels with firewall interfaces, mainly because this concept is not frequent on other vendors’ products. It is not worth it to promote the philosophical fight that comes from individual perceptions, but perhaps some insight into situations in which the concept is useful might motivate you to invest the time to fully understanding it.

In its original conception, the Adaptive Security Algorithm (ASA) determined that no connection could be set up between interfaces with equal security level. This somewhat resembles the Electricity Theory because no electrical current can flow between two points of a circuit that have the same value of electrical potential. Some practical usage scenarios are described next with the aim to facilitate the learning process.