This document provides an overview of AppleTalk: 1. AppleTalk was designed in the 1980s to allow sharing of files and printers on local area networks (LANs). It implemented a distributed client-server model where devices that supply resources like files and printers are servers and devices that use these resources are clients. 2. AppleTalk includes protocols for addressing, routing, name resolution, sessions, and transport. It supports various link layer protocols for networks like LocalTalk, Ethernet, and Token Ring. 3. The AppleTalk Manager provides programming interfaces that allow applications and processes to access AppleTalk components and services. It insulates them from the

1. AppleTalk
APPLETALK
Seminar Report
Submitted in partial fulfilment of the requirements of the
Degree of
MASTER’S OF COMPUTER APPLICATION
Department of
National Institute of Technology, Karnataka
Surathkal -575025
Submitted by: Submitted to:
Gulshan Khara Mr. Santosh
Roll No.16CA32 Panwar

2. AppleTalk
Contents
1. Abstract 3
2. Introduction 4-5
3. Component of AppleTalk network 6-7
4. Addressing in AppleTalk 8-9
5. AppleTalk Connectivity 10
6. AppleTalk Operation and Protocol stack 11-13
7. AppleTalk Manager 14
8. Advantages 14
9. Disadvantages 14
10. Conclusion 15
11. Bibliography 16

3. AppleTalk
Abstract
AppleTalk is a communications network system interconnecting personal computer workstations,
computers acting as file servers and print servers, printers, and shared modems allowing them to
exchange information through a variety of types of communications hardware and software. The
AppleTalk Manager consists of a set of programming interfaces to the various components of
AppleTalk for applications and processes running on Macintosh computers.It was designed in the
early 1980s when LANs were primarily for file exchanges and printer sharing.
AppleTalk’s purpose was to allow multiple users to share resources, such as files and printers.
The devices that supply these resources are called servers, while the devices that make use of
these resources (such as a user’s Macintosh computer) are referred to as clients. Hence,
AppleTalk is one of the early implementations of a distributed client/server networking system.
This provides a summary of AppleTalk’s network architecture

4. AppleTalk
Introduction
History
Just prior to its release in early 1985,AppleBus was renamed AppleTalk. The system had a
number of limitations, including a speed of only 230.4 Kbit/s ,a maximum distance of 1000 feet
from end to end , and only 32 nodes per LAN. But as the basic hardware was built into Mac,
adding nodes only cost about $50 for the adaptor box. In comparison,Ethernet or Token Ring
card cost hundreds or thousands of dollars. Additionally ,the entire networking stack required
only about 6KB of RAM, allowing it to run on any Mac. The relatively slow speed of AppleTalk
allows further reduction in cost. Instead of using RS-422’s balanced transmit and receive circuit,
the AppleTalk personal network cabling used a single common electrical ground, which limited
speed to about 500 Kbit/s, but allowed one inductor to be removed. This meant that common
three conductor cable could be used for wiring.Additionally, the adaptors were designed to be
“self-terminating”,meaning that nodes at the end of the network could simply leave their last
connector unconnected.

5. AppleTalk
Design:
AppleTalk was designed with a transparent network interface -that is, the interaction between
Client computers and network servers requires little interaction from the user.In addition, the
actual operations of the AppleTalk protocols are invisible end users, who see only the result of
these operations. Two versions of AppleTalk exist:AppleTalk Phase 1 and AppleTalk Phase 2.
Phase 1 and AppleTalk Phase 2.
AppleTalk Phase 1, which is the first AppleTalk specification, was developed is the early 1980’s
strictly for use in local workgroups.Phase 1 therefore has two key limitations: Its network
segment can contain no more than 135 hosts and 135 servers, and it can support only non
extended networks.
AppleTalk Phase 2, which is the second enhanced AppleTalk implementation, was designed for
use in larger internetwork. Phase 2 addresses the key limitations of AppleTalk Phase 1 and
features a number of improvements over Phase 1.In particular,Phase 2 allow any combination of
253 hosts or servers on a single AppleTalk network segment and supports both none tended and
extended networks.
Note -AppleTalk Phase 1, the original AppleTalk protocol architecture, was designed to support small local workgroups.
AppleTalk Phase 1 supported the LocalTalk Link-Access Protocol (LLAP), which was originally called the AppleTalk
Link-Access Protocol (ALAP). With the addition of the EtherTalk Link-Access Protocol (ELAP) and other link access
protocols, ALAP was renamed to indicate the specific data link that it supports.
Note-The Phase 2 versions of the AppleTalk drivers are included as part of system software version 7.0 and later. They
can be installed on any Macintosh computer other than the Macintosh 128K, Macintosh 512K, Macintosh 512K enhanced,
and Macintosh XL computers. If you want to provide AppleTalk Phase 2 drivers with your product, you must obtain a
license from Apple Software Licensing.

6. AppleTalk
Components of the AppleTalk network
AppleTalk Network Components AppleTalk networks are arranged hierarchically. Four basic
components form the basis of an AppleTalk network: sockets, nodes, networks, and zones.
Figure illustrates the hierarchical organisation of these components in an AppleTalk
internetwork. Each of these concepts is summarised in the sections that follow.
The AppleTalk is created for the tiny networks and luckily, these tiny networks can be combined
together.

7. AppleTalk
1. Sockets:
A socket in an AppleTalk is a special addressable location in the node of an AppleTalk. A
socket is a logical end where the above layer of the AppleTalk collection of programs
processes and the network layer DDP i.e. the Datagram Delivery Protocol interact. The
node of an AppleTalk can have 254 distinct socket numbers.
2. Nodes: The node is of an AppleTalk is a machine which is connected to the network of
an AppleTalk; this machine might be a device that is a Macintosh computer, a router or
some other similar machine.
3. Networks: The networks have a single logical cable and also many attached nodes and
the networks are of two types and they are as follows:
▪ Non – extended networks
▪ Extended networks
Non- extended networks: The non-extended network is a physical network part and
it is appointed with a single network number that ranges from 1 to 1024.
Extended networks: The extended networks are also called as cable range and it is
also a part of the physical network which is appointed with multiple network numbers.
4 Zones: The zone of an AppleTalk is a logical group of nodes which is defined at the
time of configuring the network by the network administrator.

8. AppleTalk
Addressing in AppleTalk:
Many components contribute to the addressing information that is used to identify the location of
an application or a process on an AppleTalk internet. This section defines these names and
numbers, and Table 1-1 highlights them.
Table 1-1 AppleTalk addressing numbers and names.
Addressing information Description
Network number A unique 16-bit number that identifies the network to which
node is connected. A single AppleTalk network can be either
extended or nonextended. An extended network is defined by
a range of network numbers.
Node ID A unique 8-bit number that identifies a node on an
AppleTalk network.
Socket number A unique 8-bit number that identifies a socket. A maximum of
254 different socket numbers can be assigned in a node.
Zone name A name assigned to an arbitrary subset of nodes within an
AppleTalk internet.
A single AppleTalk network can be interconnected with other AppleTalk networks through
routers to create a large, dispersed AppleTalk internet. A router in an internet(in appleTalk) can
select the most efficient path to the data’s intended destination, while allowing connected
networks to remain fully independent and to retain separate addresses.
Each network is assigned a network number so that packets destined for a particular network on
an AppleTalk internet can be routed to the correct network. A router consults the packet’s
destination network number and forwards the packet throughout the internet from one router to

9. AppleTalk
another until the packet arrives at its destination network. AppleTalk supports a number of types
of networks including LocalTalk, TokenTalk, EtherTalk, and FDDITalk networks.
AppleTalk assigns a node ID to a node when it connects to the network. Every node on an
AppleTalk network is identified by its unique 8-bit node ID. (Extended networks include the 16-
bit network number.) Once a packet arrives at its destination network, the packet is delivered to
its destination node within that network, based on the node ID.
More than one application or process that uses AppleTalk may be running on a single node at the
same time. Because of this, AppleTalk must have a way to determine for which application or
process a packet that is delivered to the node is intended. AppleTalk uses sockets to satisfy this
requirement. A socket is a piece of software that serves as an addressable entity on a node. Each
process or application that runs on an AppleTalk network “plugs into” a socket that is identified
by a unique number. Applications or processes exchange data with each other across an internet
through sockets. Because each application or process has its own socket address, a node can have
two or more concurrent open connections, for example, one to a file server and one to a printer.
The socket number identifies the process to which the Datagram Delivery Protocol (DDP) is to
deliver a packet. The combination of the socket number, the node ID, and the network number
creates the internet socket address of an application or process. An internet socket address
provides a unique identifier for any socket in the AppleTalk internet. When an application or
process is associated with a socket, it is referred to as a socket client.
A zone is a logical grouping of nodes in an AppleTalk internet. The use of zones allows a
network administrator to set up departmental or other logical groupings of nodes on an internet.
A single extended network can contain nodes belonging to any number of zones; an individual
node on an extended network can belong to only one zone. Each zone is identified by a zone
name.
An AppleTalk internet always consists of more than one AppleTalk network. It can be made up
of a mix of LocalTalk networks, TokenTalk networks, EtherTalk networks, and FDDITalk
networks.

10. AppleTalk
AppleTalk Connectivity
A fundamental part of a network system is its connectivity infrastructure, which includes the
communication hardware and the protocols for controlling the hardware. The communication
hardware can consist of various media including wire cabling, fiber optics cabling, and a network
interface controller (NIC), if one is used. This hardware and software constitute the data
transmission medium, which is called a data link. A data link provides nodes with access to the
network.
Nodes on a network share and compete for access to the link. The link-access protocol
implemented in the software controls the access of a node to the network hardware and makes it
possible for many nodes to share the same communications hardware. It also handles the
delivery of packets from one node to another over a network. When a packet is delivered to the
link-access protocol for transmission across the network, additional addressing and control
information is added to the packet, and the packet is called a frame.
AppleTalk connectivity is designed to be link independent, which means that it allows for the use
of various types of data links accessed through the various link-access protocols, which it
supports. AppleTalk provides the following data-link support:
■The LocalTalk Link-Access Protocol (LLAP) supports a LocalTalk link.
■ The EtherTalk Link-Access Protocol (ELAP) supports an Ethernet link.
■ The TokenTalk Link-Access Protocol (TLAP) supports a token ring link.
■The Fiber Distributed Data Interface Link-Access Protocol (FLAP) supports a Fiber
Distributed Data Interface link.
These protocols provide interfaces between the Datagram Delivery Protocol (DDP) and the types
of data-link hardware that AppleTalk can use. A user can choose to connect to any of the data
links that the node is set up to support.
AppleTalk includes a component called the Link-Access Protocol (LAP) Manager, which
insulates the higher-level AppleTalk protocols from having to identify and connect to the link
that the user has chosen; the LAP Manager connects to the selected link for them.

11. AppleTalk
The AppleTalk Operation and Protocol Stack
Devices attached to extended AppleTalk networks use two-part addresses that consist of a
network number and a node number. The network number occupies two bytes and has a range of
1 to 65,535. The node number occupies one byte and has a range of 1 to 253. This scheme
provides a range that allows for over 16 million nodes, although the physical limitation of the
cable won't actually support that many nodes. Node addresses are mapped to names that make
the network easier to access by humans. These names appear in the Macintosh graphic interface
so that users can scan for users or resources they want to contact or connect with. Name mapping
is handled by the NBP (Name Binding Protocol), as discussed later.
The AppleTalk system architecture consists of a number of protocols arranged in layers. The
various AppleTalk protocols are sets of rules, not computer programs, and so can be
implemented in many different ways on many different systems. All of the AppleTalk protocol
functions that you can address or control from a Macintosh application are implemented as
Macintosh device drivers or managers. Many other features of these protocols are implemented
in software located only on internet routers that are not used to run general applications. Some
parts of protocols are implemented by server software such as file servers or print servers.
Figure 1AppleTalk protocol stack

12. AppleTalk
AppleTalk networking is based around the concept of zones, which are logical areas that include
groups of users and resources. A zone may extend across multiple networks. Routers separate
zones, and a collection of zones is called an internet. Zones make it easier for users to find
services. For example, rather than seeing a list of all users on the network, a user sees only a list
of resources in their own zone. A zone might represent a department, a workgroup, or the floor of
a building. Zones are assigned names, such as Accounting or Sales, and appear in the Macintosh
Chooser. Choosing a zone reveals the names of devices in the zone.
The Physical Layer
Physical layer specifications define hardware connections and access methods. Ethernet, token
ring, LocalTalk, and FDDI (Fiber Distributed Data Interface) are defined in the AppleTalk
physical layer. See the related entries page for related topics.
Data Link Layer Protocols
Link access protocols for Ethernet, LocalTalk, token ring, and FDDI adapters reside in the data
link layer. The protocols are called EtherTalk, LocalTalk, TokenTalk, and FDDITalk,
respectively. A LAP manager in the data link layer is responsible for hiding the type of network
in use from upper protocols. It packages data packets produced by upper protocols for
transmission over whatever network the workstation is attached to.
Network Layer Protocols
Protocols in the network layer package data from upper layers and deliver it to the LAP manager
in the data link layer. The DDP (Datagram Delivery Protocol) exists in this layer. It packages up
to 586 bytes of data in a datagram, inserts addresses and error-checking information in a packet
header, and forwards the packet to the LAP manager.
Transport Layer Protocols
The transport layer contains the following four protocols:
• RTMP (Routing Table Maintenance Protocol) This protocol is responsible for
maintaining address tables and communicating with other routers about the status of the
network. This protocol is inefficient on WANs because it sends entire tables across the
WAN. A new version called AURP (AppleTalk Update Routing Protocol) reduces the
amount of updating that takes place over a WAN connection.

13. AppleTalk
• AEP (AppleTalk Echo Protocol) : This is responsible for determining whether a
destination node is available for a communications session before it begins. The
destination node returns an echo datagram to the sender with a response.
• ATP (AppleTalk Transaction Protocol) : This is responsible for three types of
transactions. A TREQ (transaction request) and a TRESP (transaction response) work
together, while a TREL (transaction release) closes a transaction session when it is
complete. TREQ and TRESP can determine whether requests are lost or delayed, or
whether the responder is unreachable.
• NBP (Name Binding Protocol) : This is responsible for translating the numeric Internet
address of a node into a named entity. NBP can broadcast packets over the network to
locate the network address that matches the named entity. Nodes listen for the packet and
search their name tables, then respond when a match is found.
Session Layer Protocols
The main purpose of protocols in the session layer is to establish and maintain communication
sessions between two nodes. AppleTalk contains four protocols in this layer, as described here:
• ADSP (AppleTalk Data Stream Protocol) This protocol manages data transmission
between two sockets on separate machines, providing a full-duplex byte stream if
necessary. With full duplex, both computers can transmit at the same time. Once a
connection is established, ADSP manages the flow of data.
• ASP (AppleTalk Session Protocol) This is responsible for opening and closing
sessions between two nodes and transmits session commands as necessary. ASP calls on
NBP to obtain node addresses and ATP to provide transport services for its packets.
• PAP (Printer Access Protocol) This protocol is responsible for maintaining
communication between a user's workstation and a printer. It talks to PostScript, for
example.
• ZIP (Zone Information Protocol) This protocol works with RTMP (Routing Table
Maintenance Protocol) to maintain a mapping of the network. It creates ZITs (zone
information tables) in routers that define network numbers and zone names.

14. AppleTalk
The AppleTalk Manager
Your application accesses the services of the AppleTalk protocols through the AppleTalk
Manager, which is a collection of the application programming interfaces to the AppleTalk
protocols. The AppleTalk Manager includes the LAP Manager, which collects together the
interfaces to the supported AppleTalk data links. Note that not all AppleTalk protocols have
programming interfaces.
Advantages
1. Apple automatically include AppleTalk in Macintosh operating system.
2. Easy to implement and configure.
3. Setting up a small workgroup is simple and inexpensive.
4. One of the advantages of AppleTalk relates to the design of these connection boxes.The boxes
are designed so that the continuity of the trunk call and network is maintained even I a device is
disconnected from network by unplugging it from from the connection box.
Disadvantages
1. It s not suitable for very large networks.
2. It is very slow compared to bother LAN links at 230.4 Kbps.
3. It is unsuitable for bandwidth intensive application.

15. AppleTalk
Conclusion
AppleTalk includes an address-resolution method much like TCP/IP’s ARP.The AppleTalk
version is called AARP. AARP uses broads to discover the hardware address of a node. The
primary network layer routing protocol in AppleTalk is the Datagram Delivery
Protocol(DDP).DDP Provides a best-effort connectionless datagram service.

16. AppleTalk
Bibliography
[1]. Sidhu, Gursharan; Andrews, Richard; Oppenheimer, Alan (1989). Inside AppleTalk, Second
Edition (PDF). Addison-Wesley. ISBN 0-201-55021-0.
[2]. https://developer.apple.com/legacy/library/documentation/mac/pdf/Networking/
Introduction_to_AppleTalk.pdf
[3]. Oppenheimer, Alan (January 2004). “A History of Macintosh Networking”.
[4]. S.H. Cooper and P.J. Teller ”Configure a large LAN for TCP/IP,AppleTalk and IPX”,
‘Proceeding of 20th Conference on Local Computer Networks’,Year:1995, pp.264-68.

17. AppleTalk