Juniper JUNOSE 11.1.X - LINK LAYER CONFIGURATION 4-7-2010, Configuration Manual

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ATM Interfaces
An ATM port can have a major interface and one or more subinterfaces. An ATM
subinterface is a mechanism that enables a single physical ATM interface to support
multiple logical interfaces. Several logical interfaces can be associated with a single
physical interface.
ATM subinterfaces meet the specifications in RFC 2684—Multiprotocol Encapsulation
over ATM Adaptation Layer 5 (September 1999), which replaces RFC 1483. All
references to ATM subinterfaces in this chapter are still to ATM 1483 subinterfaces.
ATM 1483 subinterfaces are identified by user-defined numbers. To select a
subinterface, you append a subinterface number to the port-level
interface atm
command.
When you create an ATM 1483 subinterface, you must configure a permanent virtual
circuit (PVC). Protocols such as ATM require one or more virtual circuits over which
data traffic is transmitted to higher layers in the protocol stack.
Figure 1 on page 4 shows a typical point-to-point ATM interface column.
Figure 1: ATM Interface Column
ATM Physical Connections
ATM interfaces and subinterfaces support two types of connections—point-to-point
and multipoint. The router defaults to point-to-point.
■
Point-to-point—Indicates a standard connection; for example, connecting two
ATM end stations
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Multipoint—Indicates a single-source end system connected to multiple
destination end systems. Multipoint indicates a nonbroadcast multiaccess (NBMA)
interface. See “ATM NBMA” on page 13.
4 ■
Overview
JUNOSe 11.1.x Link Layer Configuration Guide