1. Unit04:
Protocol Stacks

2. Overview
• Protocol
• TCP/IP
• IPX/SPX
• Appletalk
• NetBEUI

3. Protocol
• Standards define how devices communicate with each
other and access media
• Once a standard is implemented in software it becomes
a protocol
• Protocols define how devices and applications
communicate
• The protocols on a network affects the way in which it
functions and its ability to interface with other networks

4. Protocol Suite
• Transmission Control Protocol/Internet Protocol (TCP/IP)
– the most common of all network protocol suites, is the
‘standard’ in modern networks, used for
communication on the Internet
• Internet Packet eXchange/Sequence Packet eXchange
(IPX/SPX)
– developed by Novell, ensures communication
between Netware operating systems, provides similar
functionality to TCP/IP, can be routed but only to
communicate with other Netware networks
• AppleTalk
– popular networking protocol in American educational
establishments, used for communicating between
devices using the Mac OS

5. TCP/IP
• Developed for use on the Internet for the American
Department of Defence
• Two Parts:
– TCP – responsible for connection oriented
communication using error checking
– IP – implemented in the addressing system used to
identify devices
• Although designed for the Internet it is used to build
LANs, WANs and MANs
• Most widely used protocol suite, used within Unix,
Windows and Macintosh platforms

6. Features of TCP/IP
• Interoperability – has become the industry ‘standard’,
Netware have replaced two of its proprietary protocols
(IPX and SPX) with TCP and IP
• Flexibility – the multiple protocols within the suite allow a
variety of implementations, eg the use of either TCP
(reliable but slow) or UDP (fast and efficient, but not as
reliable)
• Multivendor Support – almost all network software
supports it, eg Apple, DEC, IBM, Novell, Microsoft and
Sun

7. TCP
• Designed to guarantee delivery of data from the sending
device to the receiving device
• Requires additional control information in the header
• Each data packet is placed in the correct sequence order
when it is received

8. TCP/IP
Layer

9. TCP Layer Encapsulation
22Bytes 20Bytes 20Bytes 4Bytes
64 to 1500 Bytes

10. TCP Headers

11. UDP
• Alternative to TCP is User Datagram Protocol
• Not guaranteed delivery
• No preservation of sequence
• No protection against duplication
• Minimum overhead
• Adds port addressing to IP

12. UDP Headers

13. The Internetwork Layer and IP
• The TCP/IP model’s internetwork layer deals
primarily with addressing and routing data

14. IP
• One of the most important protocols
• Developed to function within a UNIX environment in the
days of ARPAnet
• Uses connectionless delivery – it does not guarantee
delivery
• Main purpose is to provide logical addressing through
the use of an IP address
• Uses IP address to route information between networks,
therefore every device requires a unique address

15. Understanding IP Addressing
• Address consists of 4 bytes = 32 bits
• Address is quoted as four dotted decimal numbers such
as 134.220.198.170 =
10000110.11011100.11000110.10101010
• IP address consists of two parts the network portion, and
the host portion
• The network portion is used to route packets between
networks
• The host portion identifies the particular device on the
host network
• (continued in next chapter)

16. IPX/SPX
• Novell first developed its Internetwork Packet
Exchange/Sequenced Packet Exchange (IPX/SPX)
protocol suite for use with its NetWare operating system
in the 1980s
• SPX is similar to TCP in that it functions at the transport
layer and provides a connection-oriented service to
upper-layer applications

17. IPX(Internetwork Packet Exchange) and Addressing
• IPX/SPX-based networks require that each node on a
network be assigned a unique address to avoid
communication conflicts
• IPX is the component of the protocol that handles
addressing, addresses on an IPX/SPX network are
called IPX addresses
• IPX addresses contain two parts: the network address
and the node address

18. NetBEUI
• NetBIOS (Network Basic Input Output System) is a
protocol originally designed for IBM to provide Transport
and Session layer services for applications running on
small, homogenous networks
• NetBEUI can support only 254 connections, however,
and does not allow for good security
• Because NetBEUI frames include only Data Link layer
(or MAC) addresses and not Network layer addresses, it
is not routable

19. NetBEUI
• Windows Internet Naming Service (WINS) - Provides a
means of resolving NetBIOS names to IP addresses
• A computer’s NetBIOS name and its TCP/IP host name
are different entities, though you can have the same
name for both
• WINS has the same relationship to NetBIOS as DNS has
to TCP/IP
• WINS does not assign names or IP addresses, but
merely keeps track of which NetBIOS names are linked
to which IP addresses

20. Appletalk
• The protocol suite originally designed to interconnect
Macintosh computers
• An AppleTalk network is separated into logical groups of
computers called AppleTalk zones
• An AppleTalk node ID is a unique 8-bit or 16-bit number
that identifies a computer on an AppleTalk network
• An AppleTalk network number is a unique 16-bit number
that identifies the network to which a node is connected