Add traffic inspection interfaces to Layer 2 Engines

You can define both capture interfaces and inline interfaces for the same Layer 2 Engine.

When traffic is inspected, it might be important to know the interface through which it arrives to the Layer 2 Engine. It is also important to be able to distinguish a Layer 2 Engine's capture interfaces from its inline interfaces. Logical Interface elements are used for both these purposes. They allow you to group interfaces that belong to the same network segment and to identify the type of the traffic inspection interface.