HP 3000 Manuals HP 3000 Manuals
Introduction to NS3000/XL
by Gary Hypes and Mike Genevro--Information Networks Division
PRODUCT STRUCTURE
The Local Area Network Link for the HP 3000 Series 900 (ThinLAN 3000/XL
Link: HP 36921A prior to January 1, 1988; HP 36923A starting January 1,
1988) connects an HP 3000 Series 900 system to an IEEE 802.3 Local Area
Network. Hewlett-Packard Network Services, for the HP 3000 Series 900
(NS3000/XL, HP 36920A/R), provide an extension of the capabilities of the
HP 3000 Series 900 operating system (MPE XL). Both data communications
products are required to provide full networking capability. The Network
Services products are composed entirely of software and provide the user
interface to the network. ThinLAN 3000/XL Link provides everything
necessary to connect a Series 900 to an IEEE 802.3 Local Area Network.
This includes software as well as the hardware interface card, cables,
and adapters.
NS3000/XL provides an extension of the capabilities of the HP 3000 Series
900 operating system (MPE XL) and permits users to share information,
programs, processing capabilities, storage facilities, and other
resources provided by the various nodes of the distributed network.
The logical environment, in which a user or an application process gives
instructions to the computer, is called a session. In networks, sessions
which are established on remote nodes for the purpose of carrying out
data communications tasks, are called environments. The remote
environments may or may not be interactive, depending on the task
involved. To accomplish a desired task, users or processes issue
instructions similar to those they would use on their own system. In
fact, all of the MPE XL commands and most of the intrinsics can be
executed on a remote node once the remote environment is established. In
addition, a variety of NS3000/XL services are provided that include
commands or intrinsics to be used for specific tasks on remote nodes.
This variety allows the user or programmer to choose the right tool for
the task.
Services
The services provided by NS3000/XL are:
* Remote Process Management (RPM). Allows a process to programmatically
initiate and terminate other processes throughout a network from any
node on the network. RPM is normally used in conjunction with
NetIPC, the user interface supplied with the ThinLAN 3000/XL Link.
* Virtual Terminal (VT and VTR). Gives the user interactive
capabilities on the remote node, even when the user's terminal is
physically connected to the local node. Reverse VT (VTR) refers to
programmatic access of remote terminals. Because of VT design
differences between MPE XL and MPE V, Hewlett-Packard has noted some
incompatibilities between the two implementations. Hewlett-Packard
resolved some of these incompatibilities by modifying the VT
implementation for MPE V systems. The code changes to the MPE V
service appear on UB MIT. In order to execute VT successfully in a
mixed MPE V-MPE XL environment, you must update your MPE V systems to
UB MIT or later. In addition, Hewlett-Packard has made an
enhancement to VPLUS in order to recognize terminals connected to a
Distributed Terminal Controller. The MPE V version of this feature
of VPLUS is available on UB MIT and later.
* Remote File Access (RFA). Allows a user to access files and devices
on remote nodes.
* Remote Database Access (RDBA). Allows a user to access TurboIMAGE
databases on remote nodes. The same security protection used for
databases on the local node applies to remote access.
* Network File Transfer (NFT). A facility that efficiently transfers
disc files between nodes on the network.
These services enable users and programmers to perform essential
functions over an entire network.
System Requirements
NS3000/XL is supported on the HP 3000 Series 900. The system must have a
minimum of 24-megabytes of memory. Use of NS3000/XL requires the ThinLAN
3000/XL Link, which provides the hardware and software needed to connect
a Series 900 to an IEEE 802.3 coaxial cable.
ThinLAN 3000/XL Link
ThinLAN 3000/XL Link includes all the components to connect a Series 900
to a coaxial cable based on the Institute of Electrical and Electronics
Engineers (IEEE) 802.3 Standard. This standard specifies a 10 million
bits-per-second baseband local area network (LAN) with a bus topology.
The LAN uses a shielded coaxial cable as the data transmission medium and
the Carrier Sense, Multiple Access with Collision Detect (CSMA/CD) media
access method.
The base ThinLAN 3000/XL Link product connects to a thin coaxial cable; a
thick coaxial option is also available.
The figure lableled "Hardware Components" shows the two major hardware
components of the base ThinLAN 3000/XL Link product: the Local Area
Network Interface Controller (LANIC) and the Medium Attachment Unit
(ThinMAU).
ThinLAN 3000/XL Link includes software corresponding to layers 1 through
4 of the OSI Reference Model and also provides node management software.
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Hardware Components
Media Access Method
The IEEE 802.3 Standard specifies the Carrier Sense, Multiple Access with
Collision Detect (CSMA/CD) media access method. This method provides an
ideal means of transmitting bursts of data at high speeds between nodes
on a LAN. With CSMA/CD, all nodes have equal access to the network
(Multiple Access); there is no central control node. Before transmitting
data, a node monitors the network to verify that no other node is
transmitting data (Carrier Sense). If a signal is sensed, the node
desiring access defers its transmission. Although the carrier sense
makes collisions unlikely, they can occur when two nodes sense that no
other carriers are on the network and begin transmitting simultaneously.
To deal with this possibility, nodes listen for collisions while
transmitting (Collision Detect). If one is detected, the node will
initiate a jam signal to warn the entire network. All nodes must then
cease their transmission. Each delays for a random period of time and
then restarts its transmission. This means that each node eventually
gets to transmit its data.
Hardware Components
There are two major hardware components of the ThinLAN 3000/XL Link.
These are:
* Local Area Network Interface Controller (LANIC). The LANIC is a
microprocessor-based communication controller that plugs into the HP
3000 Series 900 backplane. It handles buffering, IEEE 802.2 and
802.3 protocols, and error checking, and keeps track of network
statistics. When addressed by another node on the network, the LANIC
receives frames of information and checks for accuracy of the data
before passing the frames to the host. To transmit, an addressed
frame is sent from the host to the LANIC, where error checking
information is added. The LANIC then tests to see if the cable is
busy and, if not, transmits the frame.
* Medium Attachment Unit (MAU). The Thin Medium Attachment Unit
(ThinMAU) provides the physical and electrical connection to the
network coaxial cable; it is powered by the LANIC through the
Attachment Unit Interface (AUI) cable. The ThinMAU receives signals
from and sends signals to the coax cable, and also detects collisions
resulting from two nodes starting to transmit simultaneously. The
ThinMAU also provides electrical isolation from the coaxial cable and
performs several other functions to ensure network reliability, e.g.,
if a ThinMAU fails by continuously transmitting, a circuit will
detect the failure and shut down the ThinMAU. A ThinMAU is attached
to the coaxial cable using a BNC "T" connector. The BNC "T"
connector and connector cover are included or can be ordered
separately for assembly with thin coaxial cable. Connecting a
ThinMAU to the thin cable is done by simply connecting the ThinMAU
BNC "T" connector to the thin cable BNC connectors. The ThinMAU has
an integrated 1-meter Attachment Unit Interface (AUI) cable. A
2-meter internal LANIC cable connects the LANIC to the AUI cable.
Software Components
There are four major software components of the ThinLAN 3000/XL Link.
These are:
* Network Interprocess Communication (NetIPC) provides an interface to
the Network Transport and is a peer-to-peer communications service
supplied with the ThinLAN 3000/XL Link. NetIPC allows programs,
running concurrently, to exchange information and synchronize
actions.
* The Network Transport provides the functionality of the network and
transport layers (OSI Layers 3-4), respectively. This means that the
Network Transport is responsible for moving the data from a user's
application out to the communications link and for receiving data
from the communications link and routing it to the appropriate user.
It implements the specifications of the Transmission Control Protocol
(TCP) and Internet Protocol (IP). Refer to Chapter 4 in the NS3000/XL
Network Manager Reference Manual (P/N 36920-90002) for a detailed
explanation.
* Node Management Services (NMS) provides a common set of services to
HP networking products. It includes utilities and commands for
configuration, event logging, message tracing, link management, and
subsystem initiation, termination and control.
* The link-level software implements the specifications of IEEE 802.2
and 802.3, which are the physical and data link layers (OSI Layers
1-2), respectively. There are a number of software components
provided for link management and troubleshooting.