Types of Interfaces Overview

Interfaces can be permanent or transient, and are used for networking or services:

Permanent interfaces—Interfaces that are always present in the router.
Transient interfaces—Interfaces that can be inserted into or removed from the router depending on your network configuration needs.
Networking interfaces—Interfaces, such as Ethernet or SONET/SDH interfaces, that primarily provide traffic connectivity.
Services interfaces—Interfaces that provide specific capabilities for manipulating traffic before it is delivered to its destination.
Container interfaces—Interfaces that support automatic protection switching (APS) on physical SONET links using a virtual container infrastructure.

The JUNOS Software internally generates nonconfigurable interfaces which are described in Interfaces Command Reference and Services Interfaces.