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Network Protocols

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Objectives

• Identify characteristics of TCP/IP, IPX/SPX, NetBIOS, and AppleTalk

• Understand position of network protocols in OSI Model

• Identify core protocols of each protocol suite and its functions

• Understand each protocol’s addressing scheme

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Introduction to Protocols

• Protocol– Rules network uses to transfer data

– Protocols that can span more than one LAN segment are routable

• Multiprotocol network– Network using more than one protocol

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Multiple LAN Protocols

• Advantage– Network can perform many different functions

on same LAN

• Disadvantage– Some protocols operate in broadcast mode,

causing a significant amount of redundant network traffic

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TCP/IP and Multiple Server Systems

• TCP/IP (Transmission Control Protocol/ Internet Protocol)– Most widely used protocol– Offers a suite of protocols– Protocol of the Internet– Supported by most network server and

workstation operating systems

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Transmission Control Protocol/ Internet Protocol (TCP/IP)

Suite of small, specialized protocols called subprotocols

OSI Model TCP/IP

TCP/IP compared to the OSI Model

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TCP/IP Compared to theOSI Model

• Application layer roughly corresponds to Session, Application, and Presentation layers of OSI Model

• Transport layer roughly corresponds to Transport layers of OSI Model

• Internet layer is equivalent to Network layer of OSI Model

• Network Interface layer roughly corresponds to Data Link and Physical layers of OSI Model

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The TCP/IP Core Protocols

• Certain subprotocols of TCP/IP suite– Operate in Transport or Network layers of OSI

Model– Provide basic services to protocols in other

layers of TCP/IP

• TCP and IP are most significant core protocols in TCP/IP suite

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Internet Protocol (IP)

• Provides information about how and where data should be delivered

• Subprotocol that enables TCP/IP to internetwork– To internetwork is to traverse more than one

LAN segment and more than one type of network through a router

– In an internetwork, the individual networks that are joined together are called subnetworks

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Internet Protocol (IP)

• IP datagram – IP portion of

TCP/IP frame that acts as an envelope for data

– Contains information necessary for routers to transfer data between subnets Components of an IP

datagram

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Internet Protocol (IP)

• IP is an unreliable, connectionless protocol, which means it does not guarantee delivery of data– Connectionless

• Allows protocol to service a request without requesting verified session and without guaranteeing delivery of data

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Transport Control Protocol (TCP)

• TCP– Provides reliable data delivery services

– Connection-oriented subprotocol• Requires establishment of connection between

communicating nodes before protocol will transmit data

• TCP segment– Holds TCP data fields– Becomes encapsulated by IP datagram

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Transport Control Protocol (TCP)

• Port– Address on host where application makes itself available to

incoming data

A TCP segment

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Additional Core Protocols of the TCP/IP Suite

• User Datagram Protocol (UDP)– Connectionless transport service

• Internet Control Message Protocol (ICMP)– Notifies sender of an error in transmission

process and that packets were not delivered

• Address Resolution Protocol (ARP)– Obtains MAC address of host or node

– Creates local database mapping MAC address to host’s IP address

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TCP/IP Application Layer Protocols

• Telnet – Used to log on to remote hosts using TCP/IP protocol suite

• File Transfer Protocol (FTP)– Used to send and receive files via TCP/IP

• Simple Mail Transfer Protocol (SMTP)– Responsible for moving messages from one e-mail server

to another, using the Internet and other TCP/IP-based networks

• Simple Network Management Protocol (SNMP)– Manages devices on a TCP/IP network

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Addressing in TCP/IP

• IP Address– Logical address used in TCP/IP networking– Unique 32-bit number

• Divided into four groups of octets (8-bit bytes) that are separated by periods

– IP addresses are assigned and used according to very specific parameters

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Addressing in TCP/IP

• Loopback address– IP address reserved for communicating from a

node to itself

– Value of the loopback address is always 127.0.0.1

• Internet Corporation for Assigned Names and Numbers (ICANN)– Non-profit organization currently designated by

U.S. government to maintain and assign IP addresses

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Addressing in TCP/IP

• Static IP address– IP address manually assigned to a device

• Dynamic Host Configuration Protocol (DHCP)– Application layer protocol– Manages dynamic distribution of IP addresses

on a network

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Addresses and Names

• In addition to using IP addresses, TCP/IP networks use names for networks and hosts– Each host requires a host name

– Each network requires a network name, also called a domain name

– Together, host name and domain name constitute the fully qualified domain name (FQDN)

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Advantages of TCP/IP

• International language of network communications

• Designed for use with wide range of network devices

• Main protocol of most computer operating systems

• Many troubleshooting and network analysis tools• Understood by a large body of network

professionals

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Protocols and Applications of the TCP/IP Suite

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Protocols and Applications of the TCP/IP Suite

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IPX/SPX

• Internetwork Packet Exchange/Sequenced Packet Exchange (IPX/SPX)– Protocol originally

developed by Xerox

– Modified and adopted by Novell in the 1980s for the NetWare network operating system

IPX/SPX compared to the OSI Model

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IPX/SPX Core Protocols

• Internetwork Packet Exchange (IPX)– Operates at Network layer of OSI Model– Provides routing and internetworking

services– Similar to IP in TCP/IP suite

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IPX/SPX Core Protocols

• Sequenced Packet Exchange (SPX)– Belongs to Transport layer of OSI Model– Works in tandem with IPX to ensure data are

received:• Whole• In sequence• Error free

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IPX/SPX Core Protocols

• Service Advertising Protocol (SAP)– Works in Application, Presentation, Session,

and Transport layers of OSI Model– Runs directly over IPX– Used by NetWare servers and routers to

advertise to entire network which services they can provide

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IPX/SPX Core Protocols

• NetWare Core Protocol (NCP)– Works within Presentation and Sessions

layers of OSI Model– Works over IPX– Handles requests for services between clients

and servers

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Addressing in SPX/IPX

• IPX address– Address assigned to a device on an IPX/SPX

network– Contains two parts:

• Network address (external network number)

• Node address

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NetBIOS and NetBEUI

• Network Basic Input Output System (NetBIOS)– Originally designed by IBM to provide

Transport and Session layer services– Adopted by Microsoft as its foundation

protocol– Microsoft added Application layer

component called NetBEUI

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NetBIOS and NetBEUI

• NetBIOS Enhanced User Interface– Fast and efficient protocol– Consumes few network resources– Provides excellent error correction– Requires little configuration– Can handle only 254 connections– Does not allow for good security

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NetBEUI and Microsoft Windows Servers

• NetBEUI (NetBIOS Extended User Interface)– Developed by IBM in mid-1980s– Incorporates NetBIOS for communications

across a network– Native protocol for Windows NT Server– Not routable; most suited for small LANs

using older Microsoft or IBM operating systems

– Corresponds with several layers of OSI model

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Why NetBEUI Works Well on Microsoft Networks

• Simple to install• Handles large number of communication

sessions on one network• Low memory requirements; can be quickly

transported over small networks• Fast and efficient protocol• Consumes few network resources• Provides excellent error detection and correction• Requires little configuration

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Disadvantages of NetBEUI

• Inability to route medium-sized and large networks; not enough information in NetBEUI frame to identify specific networks

• Few network analysis tools

• Does not allow for good security

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NetBIOS and NetBEUI Compared to the OSI Model

NetBIOS/NetBEUI compared to the OSI Model

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AppleTalk

• Protocol suite used to interconnect Macintosh computers

• Originally designed to support peer-to-peer networking among Macintoshes

• Can now be routed between network segments and integrated with NetWare- and Microsoft-based networks

• AppleTalk networks are separated into logical groups of computers called AppleTalk zones

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AppleTalk and Mac OS

• AppleTalk– Peer-to-peer protocol used on networks for

communications between Macintosh computers

– Connectivity supported by Windows NT, Windows 2000, Windows .NET, and NetWare Server

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AppleTalk Peer-to-Peer Networking

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Comparison of AppleTalk Phase I and Phase II

Phase 1 Phase IINo internetworking; allows only one zone

Permits internetworking; up to 255 zones

Maximum number of stations: 254

Maximum number of stations: several million

Addressing accomplished by providing a node ID

Addressing uses combination of node ID and network identification

Functions only on a network in which it is the sole protocol

Can work on a network that uses multiple protocols

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Services of AppleTalk

• Remote access to network files via AppleShare File Server Application

• Printing services through AppleShare Print Server application

• File services to DOS- and Windows-based systems via AppleShare PC application

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AppleTalk and OSI Model

AppleTalk protocol compared to OSI Model

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AppleTalk Subprotocols

• AppleShare• AppleTalk Filing Protocol (AFP)• AppleTalk Session Protocol (ASP)• AppleTalk Transaction Protocol (ATP)• Name Binding Protocol (NBP)• Routing Table Maintenance Protocol (RTMP)• Zone Information Protocol (ZIP)• Datagram Delivery Protocol (DDP)

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Addressing in AppleTalk

• AppleTalk node ID– Unique 8-bit or 16-bit number identifying a

computer on an AppleTalk network

• AppleTalk network number– Unique 16-bit number identifying the network

to which a node is connected