Understanding Interfaces

Interfaces act as a doorway through which traffic enters and exits a device. Juniper Networks devices support a variety of interface types:

• Network interfaces—Networking interfaces primarily provide traffic connectivity.
• Services interfaces—Services interfaces manipulate traffic before it is delivered to its destination.
• Special interfaces—Special interfaces include management interfaces, the loopback interface, and the discard interface.

Each type of interface uses a particular medium to transmit data. The physical wires and Data Link Layer protocols used by a medium determine how traffic is sent. To configure and monitor J Series or SRX Series device interfaces, you need to understand their media characteristics, as well as physical and logical properties such as IP addressing, link-layer protocols, and link encapsulation.

Note: Most interfaces are configurable, but some internally generated interfaces are not configurable.