Introduction to Networking for NonStop S-Series Servers

HP NonStop S-Series Systems Network Architecture
(SNA) Network Connections
Introduction to Networking for HP NonStop S-Series Servers—520670-005
7-2
Node Types
Node Types
Systems and some other devices in an SNA network are called nodes. Nodes are
characterized by their unique functions. There are four node types as follows:
Network Addressable Units (NAUs)
Each node contains network addressable units (NAUs)—logical entities that allow
control and manipulation of node resources. There are three kinds of NAUs:
Different types of LUs and PUs are distinguished by number. For example, a PU of
type 4 resides in a communications controller. An LU of type 6.2 is a particular type of
SNA LU that provides a connection between its transaction programs and network
resources. Each LU 6.2 makes a set of resources available to its transaction programs,
thus facilitating interprogram communication and making it possible to distribute
Node type 5 This node type, which is also referred to as a host node,
contains an SNA access method, such as Advanced
Communications Function/Virtual Telecommunications Access
Method (ACF/VTAM), and controls all network components; in a
network with multiple hosts, each host node controls a subset of
the network, called a domain.
Node type 4 This node type, which is also referred to as a communications
controller node, runs Advanced Communications
Function/Network Control Program (ACF/NCP) under the
direction of a host node and controls the attached links and
workstations.
Node type 2 This node type, which is also referred to as a peripheral node,
can be a workstation, a cluster controller and connected
workstations, or a distributed processor.
Node type 2.1 Nodes of this type, which include low-entry networking (LEN)
nodes, end nodes, and network nodes, can communicate as
peers, without the control of a host.
Logical units (LUs) An LU provides end users, including applications, with
access to the network; a node can have multiple LUs, one
LU, or none at all. (A node that does not support end users
need not have an LU.)
Physical units (PUs) A PU manages resources of its node and supports
communication between nodes; PUs correspond, in
general, to kinds of physical devices—for example, a host
node, a communications controller, or a terminal.
System service control
points (SSCPs)
An SSCP resides in a host node and provides services for
controlling network resources. An SNA domain consists of
an SSCP and the resources it controls.