Network Protocols

							            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 the
                  OSI 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




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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 II
 No internetworking; allows   Permits internetworking; up
 only one zone                to 255 zones
 Maximum number of            Maximum number of
 stations: 254                stations: several million
 Addressing accomplished      Addressing uses
 by providing a node ID       combination of node ID
                              and network identification
 Functions only on a          Can work on a network
 network in which it is the   that uses multiple protocols
 sole protocol
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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




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