HP OpenVMS Systems

HP Advanced Server for OpenVMS
Server Administrator's Guide

A.2.10 Alerter Service Parameters

The Alerter Service Parameters key is:

SYSTEM\CurrentControlSet\Services\Alerter\Parameters

Table A-11, Alerter Service Values, lists the values that may be stored in the Alerter Service Parameters key.

A.2.11 Application Event Log Values

The Application Event Log key is:

SYSTEM\CurrentControlSet\Services\EventLog\Application

Table A-12, Application Event Log Values, lists the values that you can store in the Application Event Log key.

A.2.12 Security Event Log Values

The Security Event Log key is:

SYSTEM\CurrentControlSet\Services\EventLog\Security

Table A-13, Security Event Log Values, lists the values that may be stored in the Security Event Log key.

A.2.13 System Event Log Values

The System Event Log key is:

SYSTEM\CurrentControlSet\Services\EventLog\System

Table A-14, System Event Log Values lists the values that may be stored in the System Event Log key.

A.2.14 User Service Parameters

The User Service Parameters key is:

SYSTEM\CurrentControlSet\Services\AdvancedServer\UserServiceParameters

Table A-15, User Service Parameter Values, lists the values that may be stored in the User Service Parameters key.

With its open architecture, the Advanced Server software can operate over several popular protocols simultaneously, including:

• TCP/IP
• NetBEUI
• DECnet Phase IV or DECnet-Plus

This appendix provides information about the following topics:

• Section B.1, Understanding the OSI Reference Model, describes the seven-layer networking software model.
• Section B.2, Choosing a Network Adapter Card, provides pointers on how to select your network adapters.
• Section B.3, Choosing a Network Protocol, briefly describes the protocols you can use, including TCP/IP, NetBEUI, and DECnet-Plus.

Before you explore the specific drivers and protocols supported by the Advanced Server, you should understand both the OSI Reference Model and the purpose of network interface card drivers. If you already understand these topics, you can skip to Choosing a Network Protocol, which includes an overview and description of each protocol that interoperates with the Advanced Server.

B.1 Understanding the OSI Reference Model

In 1978 the International Organization for Standardization (ISO) developed a model for computer networking called the Open Systems Interconnection (OSI) Reference Model. The model describes the flow of data in a computer network---from the physical connections of the network to the applications used by the end user.

The OSI Reference Model is an idealized version of networking; few systems follow it exactly. However, the model is useful for discussion and comparison of networks.

The OSI Reference Model includes seven layers, as shown in Figure B-1, OSI Reference Model. Each of the layers is responsible for a specific and discrete aspect of networking.

Figure B-1 OSI Reference Model

The following list describes each OSI Reference Model layer in detail:

• The Physical Layer is responsible for getting bits from one computer to another. It also regulates the transmission of a stream of bits over a physical medium. This layer defines how the cable is attached to the network adapter card and which transmission technique is used to send data over the cable. It also defines bit synchronization and checking.
• The Data Link Layer packages raw bits from the Physical Layer into frames. A frame is a logical, structured packet in which data can be placed. The Data Link Layer is responsible for transferring frames from one computer to another without errors. After the Data Link Layer sends a frame, it waits for an acknowledgment from the receiving computer. Frames that are not acknowledged are resent.
• The Network Layer addresses messages and translates logical addresses and names into physical addresses. It also determines the route along the network from the source to the destination computer, and it manages traffic problems such as switching, routing, and controlling the congestion of data packets.
• The Transport Layer is responsible for error recognition and recovery, ensuring the reliable delivery of messages. It also repackages messages when necessary by dividing long messages into small packets for transmission. At the receiving end, it rebuilds the small packets into the original message. The receiving Transport Layer also sends an acknowledgment of receipt.
• The Session Layer allows two applications on different computers to establish, use, and end a session. This layer establishes dialog control between the two computers in a session, regulating which side transmits, when, and for how long.
• The Presentation Layer translates data from the Application Layer into an intermediary format. This layer also manages security issues by providing services such as data encryption, and it compresses data to reduce the number of bits that need to be transferred on the network.
• The Application Layer enables end-user applications to access network services.
  When two computers communicate over a network, the software at each layer on one computer communicates with the same layer on the other computer. For example, the Transport Layer of one computer communicates with the Transport Layer on the other computer. As shown in Figure B-2, Transport Protocol, the Transport Layer on the first computer is not involved with how the communication actually passes through the lower layers of the first computer, passes across the physical media, and up through the lower layers of the second computer.

Figure B-2 Transport Protocol

A network adapter card, also called a network interface card or a network interface controller (NIC), is an adapter board installed in a computer to let it function on a network. The network adapter card provides ports to which the network cable can connect physically. The card physically transmits data from the computer to the network cable, and back.

Every network computer must have a network adapter card driver, a software driver that controls the network card. Every network adapter card driver is configured to run with a certain type of network card.

When choosing network adapter cards, you first must choose cards that support your network's architecture (such as Ethernet or Token Ring) and cabling media (such as Thinnet or twisted pair). You also should consider the tradeoffs of performance and cost.

Performance for network adapter cards depends mostly on bus width and onboard memory. The best performance is achieved when the bus width of the card closely matches the internal bus width of the computer. Onboard memory enables a card to buffer frames going to and from the network. A card with the most memory is not always the best choice. At some point, diminishing returns and the maximum speed of other network components limit the performance gains of onboard memory.

When you consider the cost of network cards, factor in the cost of buying spare cards to replace the ones that fail. You should also ensure that your network hardware budget allows for cable, hubs, repeaters, routers, and other hardware, as well as the labor costs associated with installing them.

Before you decide on a type of network card, make sure that the OpenVMS operating system you are using supports it. Also, make sure the vendor can support your business needs. If you are working with a reseller, check that the reseller has good communication with the card manufacturer.

B.3 Choosing a Network Protocol

In addition to the network card and the network card driver, a network computer must have a protocol driver, also called a transport protocol or a protocol. The protocol driver works between the upper-level network software---such as the workstation and server---and the network adapter card. The protocol packages the data that are sent over the network in a way that the computer on the receiving end will understand.

The process of associating a protocol driver with the network adapter card with which it will work and establishing a communication channel between the two is called binding.

For two computers to communicate on a network, they must use identical protocols. In the case where computers are configured to use multiple protocols, they need to have only one protocol in common to communicate. For example, a server that uses both NetBEUI and TCP/IP can communicate both with workstations that use only NetBEUI and with workstations that use only TCP/IP.

The Advanced Server allows connections from the transports and protocols shown in Table B-1, Supported Transports and Protocols.

The remainder of this section provides an overview of each of these protocols with basic information about each protocol and its advantages and disadvantages.

B.3.1 TCP/IP Protocol

TCP/IP was developed in the late 1970s as a result of a research project on network interconnection by the Department of Defense Advanced Research Projects Agency (known as ARPANet, the precursor to the Internet). TCP/IP is actually a suite of protocols that defines various interactions between computers sharing the protocol.

Since the PC began its rise in popularity, TCP/IP has become a standard protocol for support in the PC networking environment.

TCP/IP has a reputation as a difficult protocol to configure and manage. However, current implementations are making it easier. For example, in TCP/IP, the Dynamic Host Configuration Protocol (DHCP) provides server support and is one of the most important advances in PC networking. Without DHCP, system administrators had to manually assign the four-byte IP addresses to each computer. With DHCP enabled, a DHCP server can manage a range of IP addresses and assign one to each computer as it logs on to the network.

The principal advantage of TCP/IP is that it provides communication across interconnected networks with different operating systems and hardware architectures.

TCP/IP provides compatibility with the Internet, a collection of networks and gateways linking universities, corporations, government offices, and military installations worldwide.

Table B-2, TCP/IP Protocol, summarizes the advantages and disadvantages of using the TCP/IP protocol.