Transient Interfaces

Transient interfaces are any interfaces that the user can remove, move, or replace. These include ports on M-series routers, Physical Interface Cards (PICs), and J-series PIMs. Examples of transient interfaces are Fast Ethernet, Asynchronous Transfer Mode (ATM), SONET, and T1/E1, as well as service PICs such as tunnels, multilinks, link services, Adaptive Services PICs (ASPs), and passive monitoring.

Interface Naming

All JUNOS interfaces follow the same naming convention—the interface name followed by three numbers that indicate the location of the actual interface. The general convention is illustrated by the interface sequence MM-F/P/T, where:

  • MM = media type

  • F = chassis slot number

  • P = PIC slot number

  • T = port number

Media type

The first part of the interface name is the interface media name (MM) indicating the type of interface. Common interface media names include:


Aggregated Ethernet, a logical linkage of multiple Ethernet interfaces defined in the IEEE 802.3ad standard.


ATM, which sends fixed 53-byte cells over the transport media. This interface could also be used for ATM over digital subscriber line (DSL) connections.


Physical Integrated Services Digital Network (ISDN) interface.


Standard digital communication standard over copper at a rate of 2.048 Mbps, used mostly in Europe.


Standard digital communication standard over copper at a rate of 34.368 Mbps, used mostly in Europe.


Basic physical layer standard used by the digital signal level ...

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