Interfaces Fundamentals for Junos OS Evolved

Use this guide to configure, monitor and troubleshoot various interfaces on Juniper Networks devices using Junos OS.

Table 1: Interface Basics
Interfaces	Description
Device Interfaces	Device interfaces are the ports and logical endpoints used to connect the device to networks or internal subsystems. See Device Interfaces.
Physical Interfaces	A physical interface is a connection between a system and a network. It consists of a software driver and a connector to which you connect network media. See Physical Interfaces.
Logical Interfaces	A logical interface abstracts a main interface and captures its physical characteristics. A VLAN uses logical interfaces to create a virtual network. See Logical Interfaces.
Damping Interfaces	Damping interfaces reduce the impact of interface flaps. They delay or suppress the advertisement of state changes. See Damping Interfaces.
Discard Interfaces	The discard interface is a virtual interface that silently discards packets as the packets arrive. See Discard Interfaces.
Loopback Interfaces	A loopback interface is a virtual, software-based interface on a network device that remains active and reachable. Use it to test and debug network connectivity and assign a permanent IP address to a device. See Loopback Interfaces.
Serial Interfaces	A serial interface is a communication interface that transfers data one bit at a time. Serial interfaces connects devices and ensures controlled, reliable data exchange over a single channel. See Serial Interfaces.
Demultiplex Interfaces	Demultiplex (demux) interfaces are logical interfaces that share a common, underlying interface. See Demultiplex Interfaces.

Documentation Conventions

For information about the notice icons and text and syntax conventions used in the documentation, see Documentation Conventions.