TCPIP Past, Present, and Future

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TCP/IP Past, Present,and Future

• Chapter 6

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Learning Objectives

• Describe the history of TCP/IP
• Explain how TCP and IP work and how UDP is
  employed instead of TCP
• Describe IP addressing and understand how to use
  it on LANs and WANs
• Explain new IP version 6 and its intended use

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Learning Objectives

• Discuss how to use application protocols in the
  TCP/IP suite
• Understand TCP/IP application protocols
• Compare TCP/IP to OSI reference model

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A Brief History of TCP/IP

• First attempt to make ARPANET available for
  universal access (1960s)
• Network Control Protocol (NCP)
• Improvements on reliable communication (1970s)
• Transmission Control Protocol (TCP)
• Initially designed for point-to-point
  communications between computers on same network
• Internet Protocol (IP)
• Initially developed to enable communications
  between computers linked to different networks or
  to WANs

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TCP/IP

• Language computers use to talk over Internet
• Protocol of choice for most medium- and
  large-sized networks
• Good choice for most LAN-to-WAN installations
• Broad acceptance
• Reliable history
• Extensive capabilities

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Understanding TCP/IP

• Layered set of protocols similar to, but not
  identical to, OSI protocol layers
• Consists of nearly 100 nonproprietary protocols
  that interconnect computer systems efficiently
  and reliably
• Core components
• Transmission Control Protocol (TCP)
• User Datagram Protocol (UDP)
• Internet Protocol (IP)

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How TCP Works

• Establishes communication sessions between
  networked software application processes
• Provides reliable end-to-end delivery of data by
  controlling data flow
• Sequencing and acknowledging frames

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TCP Frame
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TCP Source andDestination Ports
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TCP Ports
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How UDP Works

• Connectionless alternative to TCP that yields a
  lower overhead, but is less reliable
• Relies only on checksum to ensure reliability
• Handles and transmits data faster performs no
  flow control, sequencing, or acknowledgment

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UDP Frame
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How IP Works

• Enables packets to reach a destination on a local
  or remote network by using dotted decimal
  addressing
• Used in combination with TCP or UDP

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Transport Options Compatible with TCP/IP

• Ethernet
• Token ring
• X.25
• FDDI

• ISDN
• DSL
• Frame relay
• ATM (with conversion)

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Basic Functions of IP

• Data transfer
• Packet addressing
• Packet routing
• Fragmentation
• Simple detection of packet errors

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IP as a Connectionless Protocol

• Provides network-to-network addressing and
  routing information
• Changes size of packets when size varies between
  networks

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TCP/IP Packet Encapsulation
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IP Packet
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How IP Addressing Works

• Identifies specific node and network on which it
  resides
• Each IP address is unique
• Dotted decimal notation format
• 32-bits long four fields
• Five classes (Class A through Class E)
• Reflect size of network and whether packet is
  unicast or multicast

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Role of the Subnet Mask

• Designated portion of IP address used to
• Indicate class of addressing used on a network
• Divide network into subnetworks to control
  network traffic

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Creating Subnetworks

• Using a subnet mask to divide a network into
  smaller networks
• Enables Layer 3 devices to ignore traditional
  address class designations
• Creates more options for segmenting networks
  through multiple subnets and additional network
  addresses
• Classless Interdomain Routing (CIDR) addressing
• Newer way to ignore address class designation
• Provides more IP address options for medium-sized
  networks

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How IPv6 Works

• Provides logical growth path from IPv4 so that
  applications and network devices can handle new
  demands
• Replaces class-based addresses
• Designed to be CIDR-compliant
• Offers options to create distinctions within a
  single address

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Features of IPv6

• 128-bit address capability
• Single address associated with multiple
  interfaces
• Address autoconfiguration and CIDR addressing
• 40-byte header instead of IPv4s 20-byte header
• New IP extension headers can be implemented for
  special needs, including more routing and
  security options

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IPv6 Autoconfiguration Techniques

• Stateful autoconfiguration
• Employs server management software and leases to
  automatically assign IP addresses based on
  parameters set by network administrator
• Based on Dynamic Host Configuration Protocol
  (DHCP)
• Stateless autoconfiguration
• Network device assigns its own IP address without
  obtaining it from a server

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Types of IPv6 Packets

• Unicast
• Anycast
• Multicast

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Fields of the IPv6 Header
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IPv6 Extension Headers

• Hop-by-hop
• Routing
• Fragment
• Authentication
• Encapsulating security payload
• Destination options

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Example of Extension Headers in an IPv6 Packet
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Determining Packet Size

• Using information acquired from maximum
  transmission unit (MTU) path discovery, the
  sending node fragments packets and includes
  fragment extension header
• Authentication extension header ensures that the
  datagram is received s it was sent

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Encryption and the IP Packet

• Using encapsulating security payload extension
  header
• Supports key encryption techniques compatible
  with Data Encryption Standard (DES) security

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TCP/IP Application Protocols

• Telnet
• File Transfer Protocol (FTP), Trivial File
  Transfer Protocol (TFTP), and Network File System
  (NFS)
• Simple Mail Transfer Protocol (SMTP)
• Domain Name System (DNS)
• Dynamic Host Configuration Protocol (DHCP)
• Address Resolution Protocol (ARP)

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Telnet

• Provides terminal emulation
• Comes with nearly all vendor implementations of
  TCP/IP
• Open standard
• Supported by wide range of workstations

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Telnet Encapsulated in TCP
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Telnet Communications Options

• 7- or 8-bit compatibility
• Use of different terminal nodes
• Character echoing at sending and receiving ends
• Synchronized communications
• Transmission of character streams or single
  characters
• Flow control

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FTP

• Transfers files in bulk data streams
• Uses two TCP ports (20 and 21)
• Commonly used on the Internet

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Sample FTP Commands
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TFTP

• Designed for transfer of files that enable a
  diskless workstation to boot
• Connectionless runs within UDP
• Intended for transfer of small files when data
  transmission errors are not critical and there is
  no need for security

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NFS

• Transfers information in record streams instead
  of in bulk file streams
• Connection-oriented
• Suited to computers that perform high-volume
  transaction processing involving records stored
  within data file of databases

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SMTP

• Designed for exchange of electronic mail between
  networked systems
• No login ID/password required for remote system
• Can send only text files
• Two parts to messages
• Address header
• Message text

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SMTP
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DNS

• Converts a computer or domain name to an IP
  address or converts an IP address to a computer
  or domain name (resolution)
• Two parts of computer name, divided by _at_
• Name of computer or node
• Name of organization (root domain name)

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Internet Top Level Domain Conventions
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Country Names for Domains
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Examples of Proposed TLDs
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DNS

• DNS resolvers and namespaces
• Use of zones
• Forward lookup zone
• Host address (A) resource record
• Reverse lookup zone
• Pointer (PTR) resource record

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DNS

• DNS server roles
• Primary DNS server
• Secondary DNS server
• Makes sure there is a copy of primary DNS
  servers data
• Enables DNS load balancing
• Can be spread to different parts of a network
• DNS standards
• Service resource record
• DNS dynamic update protocol

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DHCP

• Automatically leases IP addresses to computers on
  a network

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ARP

• Enables computer/device to determine MAC address
  of another computer/device
• Reverse Address Resolution Protocol (RARP)
• Used by a network node to determine its own IP
  address

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SNMP

• Gathers network performance information for
  troubleshooting
• Developed in 1980s to provide alternative to OSI
  standard for network management, Common
  Management Interface Protocol (CMIP)

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Advantages of SNMP

• Operates independently on the network
• Does not depend on two-way connection at protocol
  level with other network entities
• Can analyze network activity
• Management functions are carried out at a network
  management station
• Lower memory overhead than CMIP

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SNMP

• Node types used with SNMP
• Network management station (NMS)
• Network agents
• Management Information Base (MIB)
• Database of network performance information
  stored on a network agent for access by a network
  management station

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MIB Variables
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Improvements in SNMP v2

• Encrypted community name
• Improved error handling
• Multiprotocol support
• Support for IPX and AppleTalk
• Fast data transmission and ability to retrieve
  more MIB-II information at one time

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Monitoring with SNMP and SNMPv2

• Network Associates Sniffer software
• Microsofts Network Monitor
• Remote Network Monitoring (RMON)

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Other TCP/IP Application Protocols

• Archie
• Bootstrap Protocol (BOOTP)
• Distance Vector Multicast Routing Protocol
  (DVMRP)
• Finger
• Gopher

• Hypertext Transfer Protocol (HTTP)
• Internet Group Management Protocol (IGMP)
• Multicast Open Shortest Path First Protocol
  (MOSPF)

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Other TCP/IP Application Protocols

• Open Shortest Path First (OSPF)
• Ping
• Real-Time Protocol (RTP)
• Real-Time Transport Control Protocol (RTCP)

• Resource Reservation Protocol (RSVP)
• Routing Information Protocol (RIP)
• Simple Network Management Protocol (SNMP)
• Traceroute (tracert)

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TCP/IP and OSI Reference Model Compared
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Chapter Summary

• TCP/IP details
• Internals of the TCP and IP packets
• IP addressing
• UDP as alternative to TCP
• When communications acknowledgement is not as
  important as speed and low overhead
• IPv6 compared to IPv4

continued
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Chapter Summary

• Application protocols associated with TCP/IP for
• Terminal emulation
• File transfers
• E-mail
• Address naming conversions
• IP address assignment
• Network management
• How TCP/IP relates to OSI reference model