Managing AppleTalk on a VINES Network

Chapter 1 - Overview of AppleTalk on VINES Networks

Introducing AppleTalk

AppleTalk is a set of network protocols developed by Apple Computer as a general purpose networking system. Devices that support the AppleTalk protocols can communicate with each other. (In an AppleTalk network, a device in the network is called a node. Workstations and printers, for example, are nodes in an AppleTalk network.) Some devices, such as the Apple Macintosh computer, the Apple LaserWriter printer, and the Apple IIGS® computer have built-in hardware support for the AppleTalk protocols.

VINES Version 5.0 and greater supports AppleTalk protocols on a VINES network. The AppleTalk protocols reside in the VINES kernel, but remain inactive on the server until the server is configured and the AppleTalk software is started from the server console. VINES can also operate with other AppleTalk routers such as the Apple Internet Router, the Shiva FastPathTM , and the Cayman GatorBox® .

The AppleTalk protocols that reside in the VINES kernel allow AppleTalk-compatible devices to communicate over a VINES network. A server on which the AppleTalk software is configured can communicate with Macintosh workstations anywhere on the network.

With VINES 5.0 and greater, all the supported Ethernet, StarLANTM , Token-Ring, and LocalTalk cards can be used for AppleTalk communications. These same cards can support multiple protocols (such as VINES and TCP/IP) concurrently.

Since the AppleTalk protocols run on a VINES network, your network is not limited to Macintosh workstations; the same LAN segments can also include DOS workstations and OS/2 workstations.

Using a feature called tunneling, Macintosh workstations on your network can communicate across servers running 4.xx versions of VINES. Tunneling means that a server on which the AppleTalk protocol is not configured can still forward AppleTalk information that it receives from one server to other servers on the network, but it cannot accept any information from or provide any information to a Macintosh workstation. "VINES Tunneling" in Chapter 2 describes this feature in more detail.

AppleTalk Phase 1 and Phase 2

AppleTalk was introduced in 1985 as a general purpose network system for Macintosh workstations. Though it met some of its original goals of simplicity, decentralized network control, and ease of installation, it was limited in the number of workstations it could support.

The original AppleTalk is now referred to as AppleTalk Phase 1, and the AppleTalk introduced in 1989 is referred to as AppleTalk Phase 2. Since AppleTalk Phase 2 has extended addressing features such as network ranges and multiple zone names per LAN segment, networks using Phase 2 are often referred to as extended AppleTalk networks.

Phase 1 AppleTalk supports LocalTalk or Ethernet networks. Phase 2 supports LocalTalk, Ethernet, or Token-Ring networks.

Phase 2 offers improved performance by reducing network traffic. One way Phase 2 reduces network traffic is by having end nodes select the best router. (An end node is a non-routing node.)

Another way that Phase 2 furthers network efficiency is to reduce routing traffic by using a technique called split horizon. When sending routing table updates, a router chooses what information it sends to its neighbor routers. It does not send information about networks that it can reach through that neighbor router; this would be redundant information since that router already knows about those networks.

VINES servers support AppleTalk Phase 1 and AppleTalk Phase 2. Apple Computer recommends that you use Phase 2.

Phase 2 is described in Chapter 2 and Chapter 3. Phase 1 is described in Appendix A.

LocalTalk Networks

LocalTalk, a cabling system developed by Apple Computer, was originally called AppleTalk. Now, however, AppleTalk refers to the protocol family, and LocalTalk refers to the cabling method.

LocalTalk cabling does not support extended addressing features. An AppleTalk LAN segment connected by LocalTalk cabling, in effect, is limited to the non-extended features of the AppleTalk Phase 1 protocols. This is true even if newer model Macintosh workstations with built-in Phase 2 protocols-like the Macintosh IIfx- are part of the LAN segment.

Even though a non-extended network can support 254 nodes, a LocalTalk network, because it cannot support extended addressing features, can support a maximum of only 32 nodes. To reach the non-extended maximum of 254 nodes using LocalTalk cabling, you need separate networks, or LAN segments, connected to an internet router.

Internet routers are described in "Planning the Network Topology" in Chapter 2.

LocalTalk networks are discussed in Chapter 2, Chapter 3 and Appendix A.

Ethernet Support

In an AppleTalk environment, Ethernet networks use standard Ethernet cables and the EtherTalk software. EtherTalk is the AppleTalk data link access protocol for Ethernet for Apple computers. An Ethernet network is faster and provides more nodes than LocalTalk, supports either AppleTalk Phase 1, or AppleTalk Phase 2, with its extended addressing features.

To run AppleTalk on an Ethernet network, you need an Ethernet card in the Macintosh workstation, an Ethernet card in the server, and the EtherTalk software, which is supplied with the workstation card.

"Connecting to a VINES Ethernet Network" in Chapter 2 describes connecting to an Ethernet network.

Token-Ring Support

Phase 1 AppleTalk does not support a Token-Ring network. AppleTalk Phase 2 uses the TokenTalk software to participate in a Token-Ring network. TokenTalk is the AppleTalk data link access protocol for Token-Ring.

To use TokenTalk, each Macintosh workstation must have an Apple TokenTalk card and the server to which the workstations on the ring are connected must have a compatible Token-Ring card. You must also have the TokenTalk software, which is supplied with the workstation card.

"Connecting to a VINES Token-Ring Network" in Chapter 2 describes connecting to a Token-Ring network.

Mixed Networks

You can have both Phase 1 nodes and Phase 2 nodes in the same network. However, they are restricted to non-extended addressing unless you use a transition bridge. A transition bridge is hardware, often combined with software, that performs protocol conversion between extended and non-extended, Phase 1 and Phase 2 devices, on the same network.

As the name implies, transition bridges are not intended for long-term use, but are instead used during the time when a network is being switched from Phase 1 to Phase 2. "Mixing Phases in a Network" in Chapter 2 discusses transition bridges.

If you have more than one server, the best solution is to use the VINES tunneling feature to connect a Phase 1 and a Phase 2 network. "VINES Tunneling" in Chapter 2 describes this.

A Phase 2 internet router can combine all three dissimilar network types in the same network: Token-Ring, LocalTalk, and Ethernet.

"Mixing Phases in a Network" in Chapter 2 describes combining Phase 1 and Phase 2 networks.

AppleTalk Zones

AppleTalk networks use zones. A zone is an arbitrary designation for a particular segment of the network, or subset of nodes. Zones allow you to logically group together different resources, regardless of physical location. You can configure your network so that any node in any part of the network can belong to any zone.

For example, if people in a particular work group are situated throughout a building, all can belong to the same zone. The resources they share can also be assigned to the same zone. For example, the resources belonging to the Engineering department can be grouped together in a zone called Engineering. Users can view the resources (including devices such as printers and file servers) for Engineering alone rather than the resources for the entire network. This makes it easier and quicker to find a particular resource.

In an extended network (such as a Phase 2 network using EtherTalk), a user's zone is not tied to physical location; the zones are logical zones. You specify that a node initially belongs to a particular zone by default. The user or resource associated with that node belongs to that default zone until a different zone is explicitly selected, even if the node physically moves.

For example, if a member of the Sales department, whose zone is called SALES, moves to another part of the building, that person can still belong to the SALES zone; if the zone is not already part of the new area' s zone list, it can be added. (Zones and zone lists are discussed further in Chapter 2 and Chapter 3.)

Conversely, a user or resource can change zones without physically moving. For example, if a user changes departments, but is still located in the same place, that person can change to the zone to which the new department belongs.

A non-extended network like an AppleTalk Phase 1 network, or a Phase 2 network using LocalTalk, is limited to one zone per LAN segment. An extended network can have more than one zone per LAN segment.

For more information on AppleTalk zones, see "Assigning Zones" in Chapter 2 and "Managing AppleTalk Zones" in Chapter 3.

AppleShare Support in a VINES Network

AppleShare is the service-level implementation of the AppleTalk Filing Protocol (AFP) that provides file sharing to networked Macintosh workstations. AFP is one of the protocols that make up the AppleTalk protocol family. These protocols are described in "Interaction Between VINES and AppleTalk" .

On a VINES network, AFP is implemented as a service on the server, and the VINES server functions as an AppleShare file server. (AFP runs in addition to the VINES File Services that run on the server.) Both VINES AFP and AppleShare use the AppleTalk protocols as a base. To a Macintosh user on a VINES network, the VINES AFP service looks like an AppleShare file server.

In addition to handling file sharing, the VINES AFP service maps DOS filename extensions to Macintosh file types and file creators and passes login information to and receives authentication information from the security service.

After you configure AppleTalk for your VINES network, you use VINES configuration menus to configure the VINES AFP service.

The VINES AFP configuration menus are described in Managing VINES Services.

PAP-Compatible PostScript Printers in a VINES Network

VINES revision 5.0 supports the Apple LaserWriter printer and other Printer Access Protocol (PAP)-compatible PostScript printers. The printer must be attached to a network cable (LocalTalk or Ethernet) and cannot be directly attached to the serial or parallel ports of a server.

The Apple LaserWriter must be a networked model if you want to print across the network. For example, the Apple Personal LaserWriter LS is a LaserWriter printer, but cannot communicate across a network. You could use this printer as a local printer on a Macintosh workstation, but it would not be visible to the network.

The Apple Personal LaserWriter LS uses a serial interface. Other Apple LaserWriter printers use LocalTalk cabling, which allows them to connect to a network. You can connect a LocalTalk LAN segment to a server using a DaynaTALKTM card. (The DaynaTALK card is described in "Connecting a LocalTalk Network to a VINES Network" in Chapter 2 and also in Appendix B.) The LAN segment can support Macintosh workstations as well as the printer.

LocalTalk is described in "LocalTalk Networks". EtherTalk is described in "Ethernet Support". For more information on printing services and other services, see Managing VINES Services.

Interaction Between VINES and AppleTalk

The AppleTalk network system relies on a set of rules, or protocols, which are referred to as the AppleTalk protocols. These protocols are divided into layers, with each layer providing specific services. Table 1-1 shows the AppleTalk layers and how they correspond to the seven layers in the ISO (International Standards Organization) model.

Note that AppleTalk Filing Protocol and PostScript overlap layers 7 and 6, the Application and Presentation layers. Also, AppleTalk Data Stream Protocol (ADSP) is not supported in VINES revision 5.0.

On the server, the AppleTalk protocols reside in the kernel, along with other protocol families like TCP/IP. A protocol' s layers are sometimes collectively referred to as a protocol stack. In addition to the AppleTalk protocol stack, VINES supports other protocol stacks such as TCP/IP. Since these protocols run in the VINES kernel together, VINES is said to support them as parallel stacks. Table 1-2 compares the VINES and AppleTalk protocols.

In a layered architecture, data moves from layer to layer. Each layer performs a specific function, and each layer adds header information to packets that contain the data. All AppleTalk packets, whether they originate on a workstation, or on a server, or on an AppleTalk network running through a VINES network, have this header information.

When the packets reach the destination VINES server, they are delivered to the AppleTalk Datagram Delivery Protocol (DDP) for handling.

The headers are what make encapsulation, or tunneling, possible. (Tunneling is described in "VINES Tunneling" in Chapter 2 and "Routing Through VINES Networks" in Chapter 3.) Tunneling allows AppleTalk packets to travel over a VINES network, through servers that are not running the AppleTalk protocol. (The AppleTalk packets are wrapped, or encapsulated, in VINES headers.) To the rest of the VINES network, they appear as normal VINES packets. If you are using TCP/IP, you might be familiar with this process. The TCP/IP Routing option can perform similar tunneling on VINES networks.

Monitoring and Optimizing a VINES Network describes protocol layers and packets in more detail.

AppleTalk Information Sources

You do not need extensive knowledge of the AppleTalk protocols to run AppleTalk on your VINES networks. The AppleTalk protocols run behind the scenes in VINES, out of your view.

If you plan to use the VINES Network and Systems Management (VNSM) software, however, it helps to know a little more about what each protocol layer does. You can find more information about the AppleTalk protocols in Monitoring and Optimizing a VINES Network. This manual describes the protocols and the statistics you can view for each protocol using VNSM.

If you want to know even more about the AppleTalk protocols, you can find more detail in the following Apple Computer publications:

	Inside AppleTalk, Second Edition
	AppleTalk Phase 2 Protocol Specification
	AppleTalk Network System Overview

This level of detail, however, is usually unnecessary unless you are writing your own network software.

What to Do Next

This book is organized serially; you should read Chapter 2, then Chapter 3, and so on. For an overview of what the major steps are in configuring and managing AppleTalk on a VINES network, see Table 1-3, which follows. You can use this table as a guide to what to do next.