Internet Protocol Suite
Internet
Protocol Suite
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The Internet protocol suite is the set of
communication protocols used for the internet and similar networks, and
generally the most popular protocol stack for wide area networks.
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It is commonly known as TCP/IP.
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It is occasionally known as the DoD model due to
the foundational influence of the ARPANET.
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TCP/IP provides end-to-end connectivity
specifying how data should be formatted, addressed , transmitted , routed and
received at the destination.
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It has 4 abstraction layer:
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Link Layer : contains communication technologies
for a local network.
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The internet layer connectes local networks,
thus establishing internetworking
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The transport layer handles host-to-host
communication
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The application layer contains all protocols for
specific data communications services on a process-to-process level. Example HTTP
specifies the web browser communication with a web server.
TCP (Transmission
Control Protocol)
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TCP is one of the core protocols of the internet
protocol suite.
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TCP provides reliable , ordered delivery of a
stream of octets from a program on one computer to another program on another
computer.
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TCP contains major internet application such as
THE WWW, email, remote administration and file transfer.
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TCP provides a communication service at an
intermediate level between an application program and the IP.
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When an application program desires to send a
large bundle of data across the internet using IP, instead of breaking the data
into IP-sized pieces and issuing a series of requests, the software can issues
a single requests to TCP.
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TCP has reliability (error recovery) this is
made possible by using sequence and acknowledgment numbers (bytes) in the TCP
header field.
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TCP can control flow of data , this uses the
window field which determines the maximum amount at a given time.
TCP
Segments Structure:
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TCP accepts data from a data stream, segments it
into chunks and adds a TCP header creating TCP segments.
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The TCP segments encapsulated into an internet
IP datagram.
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The TCP segments consists of a segment header
and data section.
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The TCP header contains 10 mandatory fields ,
and an optional extension field (Options).
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Data offset (4-bits): Specifies the size of the
TCP header in 32 bit words.
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Reserved (3-bits): For future use
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Flags (9-bits) (aka Control bits): contains 9
1-bit flags
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NS (1-bit): ECN-nonce concealment protection (RFC
3540)
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CWR (1 bit): Congestion Window Reduced (CWR)
flag is set by sending host to indicate that it received a TCP segment with the
ECE flag set ( RFC 3168)
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ECE (1-bit): ECP-Echo indicates
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URG (1-bit): indicates that the urgent pointer
field is significant
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ACK (1-bit): indicates acknowledgment field is
significant.
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PSH (1-bit): Push function, Asks to push the
buffered data to the receiving application.
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RST(1-bit): Reset the connection
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SYN (1-bit): Synchronize sequence Numbers.
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FIN (1-bit)-No more data from sender.
TCP
PORTS:
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TCP uses port numbers to identify sending and
receiving application end-points on a host or internet sockets.
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Each side of a TCP connection has an associated
16-bit unsigned port number (0-65535) reserved by the sending or receiving
application.
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Arriving TCP data packets are identified as
belonging to a specific TCP connection by its sockets.
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TCP sockets is the combination of Source host
address, source port , destination host address with his port.
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Port numbers are categorized into three basic
categories: well-known, registered and dynamic/private.
:: USER DATAGRAM PROTOCOL::
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Member of Internet Protocol Suite, and the set
of network protocol used for the internet.
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With UDP, computer applications can send message
(datagrams) to other hosts on an internet protocol network without prior communications
to set up special transmission channels or data paths.
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Attributes:
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Transaction-oriented
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Provides Datagrams
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Stateless (suitable for very large number of
client)
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Lack of retransmission delays
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Unidirectional communication
What is DATAGRAM?
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A datagram is a basic transfer unit associated with
a packet-switched network in which the delivery , arrival time, and order of
arrival are not guaranteed by the network service.
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In datagram, user only provides the destination
address.
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Datagram service routes datagram without first
creating a predetermined path, many datagram in the same group can travel along
different paths before reaching the same destination.
Structure
of Datagram:
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Each datagram has two components , a header and
a data payload.
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The header contains all the info sufficient for
routing from the originating equipment to the destination without relying on
prior exchanges between the equipment and the network.
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Headers may include source and destination
address as well as a type field.
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The payload is the data to be transported.
UDP
service Ports::::
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UDP applications use datagram sockets to
establish host-to-host communications.
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An application binds a socket to its endpoint of
data transmission, which is a combination of an IP address and a service port.
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UDP provides application multiplexing (via port
numbers) and integrity verification (via checksum) of the header and payload.
Length:
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A field that specifies the length in bytes of
the entire datagram: header and data.
The minimum length is 8 byte since that’s the length
of the header.
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