Network Interfaces
ATM standards define three protocols used across the interfaces connecting the
components of an ATM campus network:
UNI Defines the interface between an ATM User Device (such as a terminal,
router, bridge, server, workstation, or concentrator equipped with an ATM
adapter) and the ATM network. The ATM subsystem supports the private
UNI defined by the ATM Forum UNI Specification V3.1.
SSI Defines the interface between two ATM switches in the same ATM Cluster.
The SSI fully supports networking functions without the need of operator
intervention, such as routing, node failure and node recovery, backup, and
topology management by the Topology Routing Service (TRS) program.
You can define multiple SSI connections between two ATM switches. The
SSI has been developed from the Public-NNI for use in 3Com ATM
subnetworks.
NNI Defines the interface between two ATM switches belonging to different ATM
Clusters in the same subnetwork or in different subnetworks.
Operator intervention is required in order to manage networking functions
such as routing, backup, topology changes, and so on.
You can define only one NNI connection between two ATM switches.
3-6 ONcore ATM Switch/Control Module: Installation and User's Guide
