Protocols and the TCP/IP Suite Chapter-4

1
Protocols and the TCP/IP SuiteChapter-4

• By
• Dr. R. K. Rao

2
Objectives

• TCP/IP Protocol Suite
• Transmission Control Protocol/Internet Protocol
• Internet addresses
• IPv4, IPv6
• Obtaining an IP address
• How network devices obtain IP addresses

3
History and Future of TCP/IP

• The U.S. Department of Defense (DoD) created the
  TCP/IP reference model because it wanted a
  network that could survive any conditions.
• Some of the layers in the TCP/IP model have the
  same name as layers in the OSI model.

4
Application Layer

• Handles high-level protocols, issues of
  representation, encoding, and dialog control.
• The TCP/IP protocol suite combines all
  application related issues into one layer and
  ensures this data is properly packaged before
  passing it on to the next layer.

5
Application Layer Examples

• Telnet Provides the capability to remotely
  access another computer
• File Transfer Protocol (FTP) Download or upload
  files
• Hypertext Transfer Protocol (HTTP) Works with
  the World Wide Web

6
Application Layer Examples
7
Transport Layer

• Five basic services
• Segmenting upper-layer application data
• Establishing end-to-end operations
• Sending segments from one end host to another end
  host
• Ensuring data reliability
• Providing flow control

8
Transport Layer Protocols
9
Internet Layer

• The purpose of the Internet layer is to send
  packets from a network node and have them arrive
  at the destination node independent of the path
  taken.
• Internet layer protocols
• Internet Protocol (IP)
• Internet Control Message Protocol (ICMP)
• Address Resolution Protocol (ARP)
• Reverse Address Resolution Protocol (RARP)

10
Internet Layer
11
Network Access Layer

• The network access layer is concerned with all of
  the issues that an IP packet requires to actually
  make a physical link to the network media.
• It includes the LAN and WAN technology details,
  and all the details contained in the OSI physical
  and data link layers.

12
Comparing the OSI Model and TCP/IP Model
13
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.

14
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.

15
Internet Architecture

• Two computers, anywhere in the world, following
  certain hardware, software, protocol
  specifications, can communicate, reliably even
  when not directly connected.
• LANs are no longer scalable beyond a certain
  number of stations or geographic separation.

16
Internet Addresses
17
IP Addressing

• An IP address is a 32-bit sequence of 1s and 0s.
• To make the IP address easier to use, the address
  is usually written as four decimal numbers
  separated by periods.
• This way of writing the address is called the
  dotted decimal format.

18
IP Address as a 32-Bit Binary Number
19
Binary and Decimal Conversion
20
Decimal and Binary Conversion
21
IP Address Classes
22
IP Address Classes
23
IP Addresses as Decimal Numbers
24
Hosts for Classes of IP Addresses
Class A (24 bits for hosts) 224 - 2 16,777,214
maximum hosts Class B (16 bits for hosts) 216 -
2 65,534 maximum hosts Class C (8 bits for
hosts) 28 - 2 254 maximum hosts Subtracting
the network and broadcast reserved address
25
IP Addresses as Decimal Numbers
26
Network IDs and Broadcast Addresses
An IP address such as 176.10.0.0 that has all
binary 0s in the host bit positions is reserved
for the network address.
An IP address such as 176.10.255.255 that has all
binary 1s in the host bit positions is reserved
for the broadcast address.
27
Private Addresses
28
Reserved Address Space

• Network ID
• Broadcast address
• Hosts for classes of IP addresses

29
Basics of Subnetting

• Classical IP addressing
• Subnetworks
• Subnet mask
• Boolean operations AND, OR, and NOT
• Performing the AND function

30
Subnetworks

• To create a subnet address, a network
  administrator borrows bits from the original host
  portion and designates them as the subnet field.

31
Subnetworks
32
Subnet Mask

• Determines which part of an IP address is the
  network field and which part is the host field
• Follow these steps to determine the subnet mask
• 1. Express the subnetwork IP address in binary
  form.
• 2. Replace the network and subnet portion of the
  address with all 1s.
• 3. Replace the host portion of the address with
  all 0s.
• 4. Convert the binary expression back to
  dotted-decimal notation.

33
Subnet Mask
Subnet mask in decimal 255.255.240.0
34
Boolean Operations AND, OR, and NOT

• AND is like multiplication.
• OR is like addition.
• NOT changes 1 to 0, and 0 to 1.

35
Performing the AND Function
36
Range of Bits Needed to Create Subnets
37
Subnet Addresses
38
Decimal Equivalents of 8-Bit Patterns
39
Creating a Subnet

• Determining subnet mask size
• Computing subnet mask and IP address
• Computing hosts per subnetwork
• Boolean AND operation
• IP configuration on a network diagram
• Host and subnet schemes
• Private addresses

40
Determining Subnet Mask Size
Class B address with 8 bits borrowed for the
subnet 130.5.2.144 (8 bits borrowed for
subnetting) routes to subnet 130.5.2.0 rather
than just to network 130.5.0.0.
41
Determining Subnet Mask Size
Class C address 197.15.22.131 with a subnet mask
of 255.255.255.224 (3 bits borrowed)
11000101 00001111 00010110 100 00011
Network Field Network Field Network Field SN Host Field
The address 197.15.22.131 would be on the subnet
197.15.22.128.
42
Subnetting Example with AND Operation
43
Determine the Number of Valid Subnets

• How many valid subnets exist on 10.0.0.0/12 ?
• How many valid subnets exist on 10.0.0.0
  255.240.0.0 ?

44
Determining Number of Valid Hosts

• How many valid hosts exist on 150.10.0.0/20 ?
• How many valid hosts exist on 150.10.0.0
  255.255.240.0 ?

45
Determining the Subnet Number of A given IP
address

• What subnet is the address 200.17.49.200/23 a
  member of?
• On what subnet can the address 200.17.49.200/23
  be found?

46
Determining Broadcast Address and Valid IP
address Ranges

• What is the range of valid IP addresses for the
  subnet 210.210.210.0/25?
• What is the broadcast address for the subnet
  210.210.210.1/25 ?
• Which of the following IP addresses are found on
  the same subnet as the IP address
  210.210.210.1/25?

47
IP Configuration on a Network Diagram
The router connects subnetworks and networks.
48
Host Subnet Schemes
The number of lost IP addresses with a Class C
network depends on the number of bits borrowed
for subnetting.
49
IPv4 versus IPv6

• IP version 6 (IPv6) has been defined and
  developed.
• IPv6 uses 128 bits rather than the 32 bits
  currently used in IPv4.
• IPv6 uses hexadecimal numbers to represent the
  128 bits.

IPv4
50
Obtaining an IP Address
51
Obtaining an IP Address

• Static addressing
• Each individual device must be configured with an
  IP address.
• Dynamic addressing
• Reverse Address Resolution Protocol (RARP)
• Bootstrap Protocol (BOOTP)
• Dynamic Host Configuration Protocol (DHCP)
• DHCP initialization sequence
• Function of the Address Resolution Protocol
• ARP operation within a subnet

52
Static Assignment of IP Addresses

• Each individual device must be configured with an
  IP address.
• Each operating system has its own way of
  configuring TCP/IP
• Requires records to be maintained of address
  assignments- emphasizes good record keeping
• Some operating systems designed to check for
  duplicate address allocation

53
Reverse Address Resolution Protocol (RARP)

• Binds MAC addresses to IP addresses
• Devices using RARP require that a RARP
• server be present on the network to answer RARP
  requests
• If a device knows its MAC address but is unable
  to locate IP address in the ARP table, it
  initiates the process called RARP

54
Reverse Address Resolution Protocol (RARP)
The source initiates a RARP request, which helps
it detect its own IP address.
55
BOOTP IP Assignment

• The Bootstrap Protocol (BOOTP) operates in a
  client/server environment and only requires a
  single packet exchange to obtain IP information.
• BOOTP packets can include the IP address, as well
  as the address of a router, the address of a
  server, and vendor-specific information.
• Does not provide dynamic address allocation
• Administrator must add hosts and maintain BOOTP
  database
• One-to-One relationship exists between IP
  addresses and the number of hosts

56
BOOTP IP Assignment

• A client uses BOOTP to send a broadcast IP
• A BOOTP server receives the broadcast and then
  sends back a broadcast
• The client receives a frame and checks the MAC
  address. If it finds its MAC address in the
  destination field and a broadcast in the IP
  destination field, it takes and stores the IP
  address other information supplied in the BOOTP
  reply message

57
Dynamic Host Configuration Protocol

• Successor to BOOTP
• Allows a hosts to obtain IP addresses dynamically
  
• Host to obtain an IP address using a defined
  range of IP addresses on a DHCP server.
• As hosts come online, contact the DHCP server,
  and request an address.
• Entire TCP/IP configuration can be obtained in
  one message

58
DHCP Initialization Sequence
Client collects DHCP offer responses from the
server.
59
Address Resolution Protocol (ARP)

• For devices to communicate, the sending device
  needs
• Destination MAC address
• Destination IP address
• If a device knows the destination IP address, to
  communicate it needs the destination MAC address
• To obtain the MAC address the device invokes ARP

60
ARP
t
ARP enables a computer to find the MAC
address of the computer that is associated with
an IP address.
61
ARP Operation Within a Subnet
All devices on the network receive the packet and
pass to network layer only one device responds
with an ARP reply.
62
ARP Process
63
Advanced ARP Concepts

• Default gateway
• Proxy ARP

64
Default Gateway
A default gateway is the IP address of the
interface on the router that connects to the
network segment on which the source host is
located.
65
How ARP Sends Data to Remote Networks
66
Proxy ARP