Overview
ATM is a high-speed networking technology that handles data in fixed-size units called cells. It enables high-speed communication between edge routers and core routers in an ATM network.
An ATM port can have a major interface and one or more subinterfaces. An ATM subinterface is a mechanism that allows a single physical ATM interface to support multiple logical interfaces. Several logical interfaces can be associated with a single physical interface.
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. Some ATM features depend on the capabilities of individual line modules.
ATM CAC
You may set the optional connection admission control (CAC) parameters when creating and modifying ATM interfaces. When CAC is enabled, the NMC-RX application calculates the required bandwidth and compares it to the available bandwidth based on the most recent system update. You are warned if there is not sufficient bandwidth to honor the request. This calculation is executed when stacking exists and on creation and modification of VP tunnels and ATM circuits.
NBMA Interfaces
The NMC-RX software supports nonbroadcast multiaccess (NBMA) networks on E-series routers. These types of networks interconnect more than two routers and have no broadcast capabilities.
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NOTE: The NBMA feature is supported only on OC3-4 and OC12 line modules. |
NBMA provides a nonbroadcast point-to-point connection consisting of a single IP address atop several circuits. Each circuit terminates at a different physical device. For example, you can use NBMA to connect a system to multiple stations.
You can add map lists and map list entries to the NMC-RX database and statically assign destination IP addresses to ATM circuits. You can use Inverse Address Resolution Protocol (InARP) to dynamically assign IP addresses to circuits, or you can use a combination of InARP and map lists. Map lists can be empty and may exist independently of any ATM interfaces, but have no function until they contain map list entries and are associated with an ATM interface.