Expand Configuration and Management Manual (G06.24+)

Subsystem Description
Expand Configuration and Management Manual—523347-008
18-59
Expand-to-ATM Interface
Expand-to-ATM Interface
This subsection describes how the Expand-over-ATM line-handler process accesses
an Asynchronous Transfer Mode (ATM) network. You should be familiar with the
information presented in this subsection before attempting to configure, manage, or
troubleshoot an Expand network that includes ATM connections.
Topics discussed in this subsection include:
•
ATM Subsystem on page 18-59
•
Expand-over-ATM Connection Establishment on page 18-60
•
Sending and Receiving Data on page 18-62
•
Forwarding Expand-over-ATM Packets to Other Expand Line-Handler Processes
on page 18-63
ATM Subsystem
Expand-over-ATM line-handler processes do not use the Data Link Layer (OSI Layer
2) services of the Expand End-to-End protocol; instead, these line-handler processes
communicate with the ATM subsystem. The QIO mechanism is used to transfer data
between the Expand-over-ATM line-handler process and the ATM subsystem.
The ATM subsystem, which is HP’s implementation of the ATM protocol, consists of
hardware and software components that reside on a NonStop S-series server. The
ATM 3 ServerNet adapter (ATM3SA) provides one bidirectional full-duplex ATM OC3
port for connection to the User-Network Interface (UNI). The UNI is an interface point
between ATM end users and a private ATM switch, or between a private ATM switch
and the public carrier ATM network. The Expand-over-ATM line-handler process uses
the services provided by the ATM subsystem to transmit data across an ATM network.
Each ATM3SA is described by a LINE object that represents the ATM line or link
connected to the ATM3SA. Permanent virtual circuits (PVCs), switched virtual
circuits (SVCs), and ATMSAP connections through the SLSA subsystem can be
configured for an ATM line.
PVC Connections
A PVC is a permanently established virtual circuit. Each PVC is associated with a PVC
name during ATM subsystem configuration. A PVC is described by the PVC object,
which is subordinate to the LINE object.
An Expand-over-ATM line-handler process that uses a PVC connection performs
addressing by specifying a PVC name.
Note. This subsection refers to modifiers that allow you to control various aspects of the
Expand-to-ATM interface. For detailed information about these modifiers, refer to Section 17,
Expand Modifiers.