Study Theme 3: Network Protocols

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Study Theme 3Network Protocols
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Contents of Lecture

• Characteristics of TCP/IP, IPX/SPX, NetBios and
  AppleTalk
• Position of network protocols in OSI model
• Core protocols of each protocol and functions
• Protocol addressing schemes

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Introduction to Protocols

• Protocols
• Rules a network uses to transfer data
• Protocols that can span more than one LAN segment
  are routable
• Multiprotocol network using more than one
  protocol

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TCP/IP

• Family of protocols
• Central to use of the internet
• Name is derived of two of these protocols
• Transmission control protocol
• Internet protocol

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Initial Design Goals of TCP/IP

• Independent of hardware and software
  manufacturers
• Good built-in failure recovery
• Handle high error rates and still provide
  reliable end-to-end service
• Efficient with low data overhead
• Addition of new networks without service
  disruptions

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Benefits of TCP/IP

• Widely published open standard and is completely
  independent of any manufacturer
• Can send information between completely different
  computer systems running completely different
  operating systems
• Routable
• Reliable and efficient data delivery
• Common addressing scheme

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Transmission Control Protocol/internet
ProtocolTCP/IP
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TCP/IP Compared to the OSI Model

• Application layer roughly corresponds to
  application and presentation layers
• Transport layer roughly corresponds to session
  and transport layers
• Internet layer is equivalent to the network layer
• Network interface layer roughly corresponds to
  data link and physical layers

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Internet Protocol (IP)

• Provides information about where and how data
  should be delivered
• Sub-protocol enabling TCP/IP to inter-network
• Traverse more than one LAN segment and more than
  one type of network through a router
• Subnets the individual networks that are joined
  together by routers in an inter-network

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IP

• IP datagram

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Internet Protocol (IP) Properties

• IP is connectionless i.e control information is
  not exchanged prior to connection establishment
  and commencement of transmission
• Does not guarantee delivery of data
• No request for for verified session

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Transport Control Protocol (TCP)

• Provides reliable data services (transmission
  layer)
• Connection oriented (requires the establishment
  of a connection before data is transmitted)
• TCP segment
• Holds TCP data fields
• Is encapsulated by the IP datagram

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Transport Control Protocol

• Example of TCP segment

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TCP Functions Summarized

• Flow control
• Acknowledgement
• Sequencing
• Checksums
• Retransmission of lost/corrupted 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 if errors occurred and packets
  were not delivered

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TCP IP Application Layer Protocols

• Telnet log in remote hosts using TCP/IP
• File transfer protocol (FTP) used to send and
  receive files via TCP/IP
• Simple mail transfer protocol (SMTP) moving mail
  messages from one e-mail server to another
• Simple network management protocol (SNMP) manages
  devices on a TCP/IP network

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Application Protocols (Continued)

• Hypertext transfer protocol (HTTP)
• Manages communications between a web browser and
  a web server
• Address resolution protocol (ARP) references MAC
  address to IP address

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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) and separated by periods
• Contains network portion and node portion
• In TCP/IP a dotted decimal notation is used,
  e.g.
• 199.217.67.34 IP address
• 255.255.255.0 subnet mask

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Commonly Used TCP/IP Address Classes
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Addressing in TCP/IP

• Loopback address
• IP address reserved for a node communicating with
  itself
• Value of loopback address 127.0.0.1

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Addressing in TCP/IP

• Static IP address
• IP address manually assigned to a device
• Dynamic host configuration protocol
• Application layer protocol
• Manages the distribution of IP addresses on a
  network

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IPX/SPX

• Internetwork packet exchange/sequenced packet
  exchange
• Originally developed by Xerox
• Modified by Novell for the NetWare systems

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IPX/SPX Model Compared to OSI Model
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IPX/SPX Core Protocols Internetwork Packet
Exchange (IPX)

• Provides routing and network services
• Comparable to IP in TCP/IP
• Connectionless

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IPX datagram
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IPX/SPX Core Protocols SPX

• Sequence packet exchange (SPX)
• Works in tandem with IPX to ensure data are
  received whole, in sequence and error free
• Comparable to TCP in TCP/IP
• Connection-oriented

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IPX/SPX Core Protocols

• Service advertising protocol (SAP)
• - Runs directly over IPX
• - Used by NetWare servers and routers to
  advertise to entire network which services they
  can provide
• Netware core protocol (NCP)
• - Handles services for requests between clients
  and servers

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Addressing in IPX/SPX

• IPX address
• Address assigned to device on IPX/SPX network
• Example of IPX address
• 000008A20060973E97F3
• 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 for transport and
  session layer services
• Adopted by Microsoft as its core protocol
• Microsoft added application layer component
  called NetBIOS enhanced user interface (NetBEUI)

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NetBEUI

• Fast and efficient protocol
• Consumes few network resources
• Provides excellent error correction
• Requires little configuration
• Non-routable

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AppleTalk

• Protocol suite used to interconnect MacIntosh
  computers
• Originally designed to support peer-to-peer
  networking among Macintoshes
• Can be routed between network segments and
  integrated with NetWare and Microsoft-based
  networks