Expand Configuration and Management Manual (H06.21+, J06.10+)

Subsystem Description
Expand Configuration and Management Manual — 529522-013
17 - 6
Network Control Process ($NCP)
The Expand-over-ServerNet line-handler process manages security-related messages
and forwards packets outside the ServerNet cluster. Other messages, such as
incoming and outgoing data, usually bypass the Expand-over-ServerNet line-handler
process and are handled directly by the ServerNet fabrics and the NonStop cluster
switches; the Expand software is not involved.
Expand-Over-ATM Line-Handler Process
The Expand-over-ATM line-handler process uses the Asynchronous Transfer Mode
(ATM) subsystem to provide connectivity to an ATM network. The Expand-over-ATM
line-handler process communicates with the ATM subsystem through the shared
memory of the QIO subsystem.
The ATM subsystem, which is HP’s implementation of the ATM protocol, consists of
hardware and software components that reside on an Integrity NonStop NS-series
server. The ATM 3 ServerNet adapter (ATM3SA) provides one bidirectional full-duplex
ATM OC3 port for connection to the User-Network Interface (UNI). The Expand-over-
ATM line-handler process uses the services provided by the ATM subsystem to
transmit data across an ATM network.
Network Control Process ($NCP)
The network control process, $NCP, is a process in each node of an Expand network.
$NCP uses services provided by the network utility process, $ZNUP. $ZNUP is part of
the NonStop operating system.
Network Control Process Functions
The network control process, $NCP, is responsible for these functions:
•
Initiating and terminating node-to-node connections.
•
Maintaining the network-related system tables, including routing information.
•
Calculating the most efficient way to transmit data to other nodes in the network.
•
Monitoring and logging changes in the status of the network and its nodes.
•
Informing the network control processes at neighbor nodes of changes in line or
Expand line-handler process status (for example, lines UP or DOWN).
Neighbor
nodes
are two nodes that have a path configured between them.
•
Informing Expand line-handler processes when all paths are DOWN. Expand line-
handler processes respond by aborting pending requests.
•
Grouping Expand line-handler processes in a multi-CPU path to a particular
neighbor node.
Note. For more information on the Expand-to-ATM interface, see Expand-to-ATM Interface on
page 17-58.