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1. TCP/IP PROTOCOL ARCHITECTURE
-Presented by
Anyapu pranav

2. • TCP/IP stands for Transmission Control Protocol/Internet Protocol, and
• It is a set of networking protocols that allows two or more computers to
communicate via the Internet through compiling packets of data and sending them
to right location.
HISTORY:
• The TCP/IP protocol architecture is a result of protocol research and development
conducted on the experimental packet-switched network, ARPANET, funded by the
Defence Advanced Research Projects Agency (DARPA), and is generally referred to as
the TCP/IP protocol suite. This protocol suite consists of a large collection of
protocols that have been issued as Internet standards by the Internet Activities
Board (IAB).
• It was invented by Robert E. Kahn and Vint Cerf on january 1, 1983.
• It was officially came to usage in 1990 when the world wide web(WWW) was
invented.

3. The TCP/IP protocol architecture has 5 layers . They are
• Physical layer
• Network access layer
• Internet layer
• Host-to-Host layer, or transport layer
• Application layer
Physical layer:
• The physical layer covers the physical interface between a data transmission device
(e.g., workstation, computer) and a transmission medium or network. This layer is
concerned with specifying the characteristics of the transmission medium, the
nature of the signals, the data rate, and related matters.
• It specifies the characteristics of the hardware to be used for the network.
• The physical layer of TCP/IP describes hardware standards such as IEEE 802.3, the
specification for Ethernet network media, and RS-232, the specification for standard
pin connectors.

4. Network Access layer:
• It defines how the data should be sent physically through the network.
• This layer is mainly responsible for the transmission of the data between two
devices on the same network.
• The functions carried out by this layer are encapsulating the IP datagram into
frames transmitted by the network and mapping of IP addresses into
physical addresses.
• The protocols used by this layer are Ethernet, token ring, FDDI, X.25, frame
relay.
ETHERNET RS-232 CABLE RS-232 CONNECTOR PIN DIAGRAM
Image source: wikipedia.org

5. INTERNET LAYER:
• An internet layer is the third layer of the TCP/IP model.
• The main responsibility of the internet layer is to send the packets from any network,
and they arrive at the destination irrespective of the route they take.
Following are the protocols used in this layer are:
1) IP Protocol:
• IP protocol is used in this layer, and it is the most significant part of the entire TCP/IP
suite.
2) IP Addressing:
• This protocol implements logical host addresses known as IP addresses. The IP
addresses are used by the internet and higher layers to identify the device and to
provide internetwork routing.
3) Host-to-host communication:
• It determines the path through which the data is to be transmitted.

6. 4) Data Encapsulation and Formatting:
• An IP protocol accepts the data from the transport layer protocol. An IP protocol
ensures that the data is sent and received securely, it encapsulates the data into
message known as IP datagram.
5) Fragmentation and Reassembly:
• The limit imposed on the size of the IP datagram by data link layer protocol is known
as Maximum Transmission unit (MTU). If the size of IP datagram is greater than the
MTU unit, then the IP protocol splits the datagram into smaller units so that they can
travel over the local network. Fragmentation can be done by the sender or
intermediate router. At the receiver side, all the fragments are reassembled to form
an original message.
6) Routing:
• When IP datagram is sent over the same local network such as LAN, WAN, MAN, it is
known as direct delivery. When source and destination are on the distant network,
then the IP datagram is sent indirectly. This can be accomplished by routing the IP
datagram through various devices such as routers.

7. Transport Layer:
• The transport layer is responsible for the reliability, flow control, and correction of
data which is being sent over the network.
• The two protocols used in the transport layer are User Datagram protocol and
Transmission control protocol.
• User Datagram Protocol (UDP)
• It provides connectionless service and end-to-end delivery of transmission.
• It is an unreliable protocol as it discovers the errors but not specify the error.
UDP consists of the following fields:
Source port address: The source port address is the address of the application program that
has created the message.
Destination port address: The destination port address is the address of the application
program that receives the message.
Total length: It defines the total number of bytes of the user datagram in bytes.
Checksum: The checksum is a 16-bit field used in error detection.
• UDP does not specify which packet is lost. UDP contains only checksum; it does not
contain any ID of a data segment.

8. Transmission Control Protocol (TCP):
• It provides a full transport layer services to applications.
• It creates a virtual circuit between the sender and receiver, and it is active for the
duration of the transmission.
• TCP is a reliable protocol as it detects the error and retransmits the damaged frames.
Therefore, it ensures all the segments must be received and acknowledged before
the transmission is considered to be completed and a virtual circuit is discarded.
• At the sending end, TCP divides the whole message into smaller units known as
segment, and each segment contains a sequence number which is required for
reordering the frames to form an original message.
• At the receiving end, TCP collects all the segments and reorders them based on
sequence numbers.
Image source: Data and Communication textbook by William stalling’s.

9. Application Layer:
• An application layer is the topmost layer in the TCP/IP model.
• It is responsible for handling high-level protocols, issues of representation.
• This layer allows the user to interact with the application.
• When one application layer protocol wants to communicate with another application
layer, it forwards its data to the transport layer.
• There is an ambiguity occurs in the application layer. Every application cannot be
placed inside the application layer except those who interact with the
communication system. For example: text editor cannot be considered in application
layer while web browser using HTTP protocol to interact with the network
where HTTP protocol is an application layer protocol.

10. Following are the main protocols used in the application layer:
HTTP:
• HTTP stands for Hypertext transfer protocol. This protocol allows us to access the
data over the world wide web. It transfers the data in the form of plain text, audio,
video. It is known as a Hypertext transfer protocol as it has the efficiency to use in a
hypertext environment where there are rapid jumps from one document to another.
SNMP:
• SNMP stands for Simple Network Management Protocol. It is a framework used for
managing the devices on the internet by using the TCP/IP protocol suite.
SMTP:
• SMTP stands for Simple mail transfer protocol. The TCP/IP protocol that supports the
e-mail is known as a Simple mail transfer protocol. This protocol is used to send the
data to another e-mail address.
DNS:
• DNS stands for Domain Name System. An IP address is used to identify the
connection of a host to the internet uniquely. But, people prefer to use the names
instead of addresses. Therefore, the system that maps the name to the address is
known as Domain Name System.

11. TELNET:
• It is an abbreviation for Terminal Network. It establishes the connection between the
local computer and remote computer in such a way that the local terminal appears
to be a terminal at the remote system.
FTP:
• FTP stands for File Transfer Protocol. FTP is a standard internet protocol used for
transmitting the files from one computer to another computer.

12. Operation of TCP and IP:
Image source: Data and Communication textbook by William stalling’s.

13. Image source: howtogeek.com

14. • Ethernet logic, is used to connect a computer to a sub network.
• This protocol enables the host to send data across the sub network to another host
or, if the target host is on another subnetwork, to a router that will forward the data.
• IP is implemented in all of the end systems and the routers. It acts as a relay to move
a block of data from one host, through one or more routers, to another host.
• TCP is implemented only in the end systems; it keeps track of the blocks of data to
assure that all are delivered reliably to the appropriate application. For successful
communication, every entity in the overall system must have a unique address.
• Each host on a sub network must have a unique global internet address; this allows
the data to be delivered to the proper host. Each process with a host must have an
address that is unique within the host; this allows the host-to-host protocol (TCP) to
deliver data to the proper process. These latter addresses are known as ports.
• A process, associated with port 3 at host A, wishes to send a message to another
process, associated with port 2 at host B. The process at A hands the message down
to TCP with instructions to send it to host B, port 2.TCP hands the message down to
IP with instructions to send it to host B. Note that IP need not be told the identity of
the destination port. All it needs to know is that the data are intended for host B.
Next, IP hands the message down to the network access layer with instructions to
send it to router J (the first hop on the way to B).

15. • To control this operation, control information as well as user data must be
transmitted.
• the sending process generates a block of data and passes this to TCP. TCP may break
this block into smaller pieces to make it more manageable. To each of these
pieces,TCP appends control information known as the TCP header, forming a TCP
segment. The control information is to be used by the peer TCP protocol entity at
host B.
Image source: Data and Communication textbook by William stalling’s.

16. • Destination port:
• When the TCP entity at B receives the segment, it must know to whom the data are
to be delivered.
• Sequence number:
• TCP numbers the segments that it sends to a particular destination port sequentially,
so that if they arrive out of order, the TCP entity at B can reorder them.
• Checksum:
• The receiving TCP performs the same calculation and compares the result with the
incoming code. A discrepancy results if there has been some error in transmission.
• TCP hands each segment over to IP, with instructions to transmit it to B. These
segments must be transmitted across one or more subnetworks and relayed through
one or more intermediate routers. This operation, too, requires the use of control
information. Thus IP appends a header of control information to each segment to
form an IP datagram .
• Finally, each IP datagram is presented to the network access layer for transmission
across the first sub network in its journey to the destination. The network access
layer appends its own header, creating a packet, or frame.

17. • The packet is transmitted across the sub network to router J. The packet header
contains the information that the sub network needs to transfer the data across the
sub network. Examples of items that may be contained in this header include:
• Destination sub network address:
• The sub network must know to which attached device the packet is to be delivered.
• Facilities requests:
• The network access protocol might request the use of certain sub network facilities,
such as priority.
• At router J, the packet header is stripped off and the IP header examined. On the
basis of the destination address information in the IP header, the IP module in the
router directs the datagram out across sub network 2 to B. To do this, the datagram
is again augmented with a network access header.
• When the data are received at B, the reverse process occurs. At each layer, the
corresponding header is removed, and the remainder is passed on to the next higher
layer, until the original user data are delivered to the destination process.

18. TCPandUDP:
• For most applications running as part of the TCP/IP protocol architecture, the
transport layer protocol is TCP.
• TCP provides a reliable connection for the transfer of data between applications.
• A connection is simply a temporary logical association between two entities in
different systems. A logical connection refers to a given pair of port values. For the
duration of the connection each entity keeps track of TCP segments coming and
going to the other entity, in order to regulate the flow of segments and to recover
from lost or damaged segments s the header format for TCP, which is a minimum of
20 octets, or 160 bits.
Image source: Data and Communication textbook by William stalling’s.

19. UDP:(UserDatagramProtocol)
• UDP does not guarantee delivery, preservation of sequence, or protection against
duplication. UDP enables a procedure to send messages to other procedures with a
minimum of protocol mechanism.
• . UDP also includes a checksum to verify that no error occurs in the data; the use of
the checksum is optional.
Image source: Data and Communication textbook by William stalling’s.

20. References:
• Wikipedia.org
• Javatpoint.com
• Geeksforfeeks.org
• Webopedia.com
• Data and Communication textbook by William stalling’s.