Module09TCPIP Protocol Suite

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Module09-TCP/IP Protocol Suite IP Addressing
By Uditha Gamage Sri Lanka Institute of
Information Technology
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Introduction to TCP/IP
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TCP/IP model
The U.S. Department of Defense (DoD) created the
TCP/IP reference model because it wanted a
network that could survive any conditions. The
present version of TCP/IP was standardized in
September of 1981.
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Application layer
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Transport layer

• TCP and UDP
• Segmenting upper-layer application data
• Sending segments from one end device to another
  end device
• TCP only
• Establishing end-to-end operations
• Flow control provided by sliding windows
• Reliability provided by sequence numbers and
  acknowledgme

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Internet layer
The purpose of the Internet layer is to select
the best path through the network for packets to
travel IP provides connectionless, best-effort
delivery routing of packets. Internet Control
Message Protocol (ICMP) provides control and
messaging capabilities. ARP resolves MAC
address, for known IP addresses. Reverse Address
Resolution Protocol (RARP) determines IP
addresses when the MAC address is known
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Network access layer
The network access layer defines the procedures
for interfacing with the network hardware and
accessing the transmission medium. Drivers for
software applications, modem cards and other
devices operate at the network access layer
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TCP/IP Vs OSI

• Similarities of the OSI and TCP/IP models
• Both have layers
• Both have application layers, though they include
  very different services
• Both have comparable transport and network layers
  
• Packet-switched, not circuit-switched, technology
  is assumed
• Networking professionals need to know both models
  

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• Differences of the OSI and TCP/IP models
• TCP/IP combines the presentation and session
  layer into its application layer
• TCP/IP combines the OSI data link and physical
  layers into one layer
• TCP/IP appears simpler because it has fewer
  layers
• TCP/IP transport layer using UDP does not always
  guarantee reliable delivery of packets as the
  transport layer in the OSI model does

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Internet architecture
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Internet Protocol AddressesIPV4 Addressing
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IP addressing and classes

• IP addresses are 32 bits long.
• They are represented as four octets in dotted
  decimal format.

233.14.17.0

• The IP address has two components
• The network ID
• The host ID

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Network address
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Private IP addresses
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Introduction to Subnetting
Network administrators sometimes need to divide
networks, particularly large networks, into
smaller networks, called subnetworks, in order to
provide extra flexibility. Most of the time
subnetworks are simply referred to as subnets.
The primary reason for using a subnet is to
reduce the size of a broadcast domain
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• The minimum number of bits you can borrow is two.

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Calculating a Subnet

• We will subnet the IP address
• 223.14.17.0
• What class IP address is this?
• Class C
• Determine the default subnet mask
• Lets see how many subnets and hosts we will have
  by borrowing 4 bits from the host.
• Problem Given 195.137.92.0 and needing 8 usable
  subnets, find the subnetwork numbers, the ranges
  of host numbers, and subnetwork broadcast
  numbers.

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IP4 Vs IP6
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Obtaining an IP Address
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Static assignment
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RARP IP address assignment
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• Reverse Address Resolution Protocol (RARP)
• Reverse Address Resolution Protocol (RARP) binds
  MAC addresses to IP addresses.
• A network device might know its MAC address but
  not its IP address in diskless workstations or
  dumb terminals. Devices using RARP require a RARP
  server.
• A RARP request consists of a MAC header, an IP
  header, and an RARP request message.
• Workstations running RARP have codes in ROM that
  direct them to start the RARP process and locate
  the RARP server.

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BOOTP IP address assignment

• BOOTstrap Protocol (BOOTP)
• A device uses BOOTstrap Protocol (BOOTP) when it
  starts up to obtain an IP address. BOOTP uses
  UDP to carry messages the UDP message is
  encapsulated in an IP datagram.
• A computer uses BOOTP to send a broadcast IP
  datagram (using a destination IP address of all
  1s - 255.255.255.255) a BOOTP server receives
  the broadcast and then sends a broadcast.
• The client receives a datagram and checks the MAC
  address. If it finds its own MAC address in the
  destination address field, it then takes the IP
  address in that datagram.

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DHCP IP address assignment
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• Dynamic Host Configuration Protocol (DHCP)
• Dynamic Host Configuration Protocol (DHCP) has
  been proposed as a SUCCESSOR to BOOTP and RARP.
  Unlike BOOTP, DHCP allows a host to obtain an IP
  address quickly and dynamically.
• All that is required using DHCP is a defined
  range of IP addresses on a DHCP server (commonly
  referred to as a scope).
• As hosts come online, they contact the DHCP
  server and request an address. The DHCP server
  chooses an address and allocates it to that host.

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• When DHCP clients boot, they enter an initialize
  state.
• Then they send a DHCPDISCOVER broadcast message,
  which contains UDP packets with the port number
  set to the BOOTP port.
• After sending the DHCPDISCOVER, the server sends
  a DHCPOFFER response.
• The client responds by sending a DHCPREQUEST
  packet to negotiate the lease.
• The DHCP server acknowledges client requests with
  DHCPACK packets.

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Problems in address resolution
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ARP
The TCP/IP suite has a protocol called ARP that
can automatically detect the MAC address. ARP
enables a computer to find the MAC address of the
computer that is associated with an IP address
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End Of Chapter.