The document discusses the Transmission Control Protocol (TCP) which provides reliable, ordered, and error-checked delivery of data between applications running on hosts communicating via an IP network. TCP is connection-oriented and provides a byte stream service on top of the unreliable IP datagram service. It uses acknowledgments and timeouts with retransmission to provide reliability and implements flow control using a sliding window approach. TCP connections are identified by the endpoints - the IP addresses and port numbers of both the hosts. Connection establishment involves a three-way handshake and connection termination involves an orderly four-segment closing sequence.
Protocols And IP suite PPT
Contents are
History
TCP/IP Suite Layer
a} Network Interface
b} Internet Layer
c} Transport Layer
d} Application Layer
3.Comparison of OSI and IP
A distributed system is a collection of computational and storage devices connected through a communications network. In this type of system, data, software, and users are distributed.
Here, you can learn all information about Shell Script.
1. What is Shell Script?
2. Types of Shell Script.
3. Use of Shell Script.
4. Command line of Shell Script.
5. Example of Shell Script.
This slide contains details about domain name servers (DNS).
It also contains Resolution of the Name Servers with Domain Name Structure with statistics table. The process of Name resolution is also explained with Recursive and iterative resolution processes.
Hello People.. Welcome to GURUKULA!!!
Have you ever thought that how the protocols that are required for the effective delivery of the messages from one place to anpther place take place in a real time internet..... This video explains about the concept called PROTOCOL LAYERING, where you can learn the way how the protocols are layered in such a way..
Simple examples are also used to make the concepts clean nd clear.
This video will help you to learn:
What is protocol layering in networks, OSI Model in Computer Networks, Layers of OSI Model, OSI Model, OSI Internet Module, OSI Layers and their Functions, Examples of OSI Models, 7 layers of OSI Models, Principles of Protocol Layering, Why layering the Protocols,
Thanks for Watching, Keep Supporting and Keep Sharing...
Protocols And IP suite PPT
Contents are
History
TCP/IP Suite Layer
a} Network Interface
b} Internet Layer
c} Transport Layer
d} Application Layer
3.Comparison of OSI and IP
A distributed system is a collection of computational and storage devices connected through a communications network. In this type of system, data, software, and users are distributed.
Here, you can learn all information about Shell Script.
1. What is Shell Script?
2. Types of Shell Script.
3. Use of Shell Script.
4. Command line of Shell Script.
5. Example of Shell Script.
This slide contains details about domain name servers (DNS).
It also contains Resolution of the Name Servers with Domain Name Structure with statistics table. The process of Name resolution is also explained with Recursive and iterative resolution processes.
Hello People.. Welcome to GURUKULA!!!
Have you ever thought that how the protocols that are required for the effective delivery of the messages from one place to anpther place take place in a real time internet..... This video explains about the concept called PROTOCOL LAYERING, where you can learn the way how the protocols are layered in such a way..
Simple examples are also used to make the concepts clean nd clear.
This video will help you to learn:
What is protocol layering in networks, OSI Model in Computer Networks, Layers of OSI Model, OSI Model, OSI Internet Module, OSI Layers and their Functions, Examples of OSI Models, 7 layers of OSI Models, Principles of Protocol Layering, Why layering the Protocols,
Thanks for Watching, Keep Supporting and Keep Sharing...
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5-LEC- 5.pptxTransport Layer. Transport Layer ProtocolsZahouAmel1
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Transpor
why Java is so popular is the platform independence. Programs can run on several different types of computer; as long as the computer has a Java Runtime Environment (JRE) installed, a Java program can run on it.
Java is a strongly typed programming language because every variable must be declared with a data type. A variable cannot start off life without knowing the range of values it can hold, and once it is declared, the data type of the variable cannot change
Propositional Resolution is a powerful rule of inference for Propositional Logic. Using Propositional Resolution (without axiom schemata or other rules of inference), it is possible to build a theorem prover that is sound and complete for all of Propositional Logic. What's more, the search space using Propositional Resolution is much smaller than for standard Propositional Logic.
Transformation rules
Propositional calculus
Rules of inference
Implication introduction / elimination
Biconditional introduction / elimination
Conjunction introduction / elimination
Disjunction introduction / elimination
Disjunctive / Hypothetical syllogism
Constructive / Destructive dilemma
Absorption / Modus tollens /
Modus ponendo tollens
Rules of replacement
Associativity Commutativity Distributivity Double negation De Morgan's laws Transposition Material implication Exportation Tautology Negation introduction
Predicate logic
Universal generalization / instantiation
Existential generalization / instantiation
v t e
Propositional calculus (also called propositional logic, statement logic, sentential calculus, sentential logic, or sometimes zeroth-order logic) is the branch of logic concerned with the study of propositions (whether they are true or false) that are formed by other propositions with the use of logical connectives. First-order logic extends propositional logic by allowing a proposition to be expressed as constructs such as "for every", "exists", "equality" and "membership", whereas in proposition logic, propositions are thought of as atoms.
an integrated circuit that contains all the functions of a central processing unit of a computer.
In a computer system, the microprocessor is the central unit that executes and manages the logical instructions passed to it.
A microprocessor may also be called a processor or central processing unit, but it is actually more advanced in terms of architectural design and is built over a silicon microchip.
Interrupts are particularly useful when interfacing I/O devices that provide or require data at relatively low data transfer rates .
If the person using the keyboard typed one character per second. The software of the Processors waited an entire second between each key stroke for the person to type another key .
80286 is the first member of the family of advanced microprocessors with memory management and wide protection abilities.This designed for multi-user systems with multitasking applications
Macroeconomics- Movie Location
This will be used as part of your Personal Professional Portfolio once graded.
Objective:
Prepare a presentation or a paper using research, basic comparative analysis, data organization and application of economic information. You will make an informed assessment of an economic climate outside of the United States to accomplish an entertainment industry objective.
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
Unit 8 - Information and Communication Technology (Paper I).pdfThiyagu K
This slides describes the basic concepts of ICT, basics of Email, Emerging Technology and Digital Initiatives in Education. This presentations aligns with the UGC Paper I syllabus.
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
Honest Reviews of Tim Han LMA Course Program.pptxtimhan337
Personal development courses are widely available today, with each one promising life-changing outcomes. Tim Han’s Life Mastery Achievers (LMA) Course has drawn a lot of interest. In addition to offering my frank assessment of Success Insider’s LMA Course, this piece examines the course’s effects via a variety of Tim Han LMA course reviews and Success Insider comments.
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
Embracing GenAI - A Strategic ImperativePeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
2. OSI Model TCP/IP Hierarchy Protocols
7th
Application Layer
6th
Presentation Layer
5th
Session Layer
4th
Transport Layer
3rd
Network Layer
2nd
Link Layer
1st
Physical Layer
Application Layer
Transport Layer
Network Layer
Link Layer
OSI v/s TCP/IP
3. Transmission Control Protocol
(TCP)
Major transport service in the TCP/IP suite
Used for most Internet applications (esp. World Wide Web)
Connection-oriented protocol
Provides a reliable unicast end-to-end byte stream over an unreliable
internetwork.
Very complex
• Specifies format of data and acks
• Specifies how TCP software distinguishes among multiple destinations on a host
• How hosts recover from lost or duplicated packets
• How hosts initiate and terminate a transfer TCP
IP Internetwork
ByteStream
ByteStream
TCP
5. Providing Reliability
Traditional technique: Positive Acknowledgement with
Retransmission (PAR)
• Receiver sends acknowledgement when data arrives
• Sender starts timer whenever transmitting
• Sender retransmits if timer expires before
• acknowledgement arrives
6. Illustration Of Sliding Window
Window size is fixed
As acknowledgement arrives, window moves forward
Why Sliding Window Works
Because a well-tuned sliding window protocol keeps
the network completely saturated with packets, it obtains
substantially higher throughput than a simple positive
acknowledgement protocol.
8. Conceptual Layering Layering Of The Three
Major Protocols
Application
Reliable Stream (TCP) User Datagram (UDP)
Internet (IP)
Network Interface
9. Ports, Connections, and Endpoints
Like UDP, TCP resides in the transport layer
Like UDP, TCP uses protocol port numbers to identify
the ultimate destination within a host
TCP ports are much more complex than UDP ports
TCP port numbers do not correspond to a single object.
TCP is built on the connection abstraction, in which
objects are identified by connections.
A connection is a pair of endpoints.
An endpoint is a pair, (host, port).
Two connections might share one endpoint.
10. TCP connection between two endpoints identified by
four items
Sender’s IP address
Sender’s protocol port number
Receiver’s IP address
Receiver’s protocol port number
An Important Idea About Port Numbers
• Because TCP identifies a connection by a pair of
endpoints, a given TCP port number can be shared by
multiple connections on the same machine.
11. Passive And Active Opens
Two sides of a connection
One side waits for contact
• A server program
• Uses TCP’s passive open
One side initiates contact
• A client program
• Uses TCP’s active open
12. Passive and Active Opens(cntd)
• An application program on one end performs a passive open by
indicating to the OS that it will accept an incoming connection. The OS
provides a TCP port number for its end of the connection.
• An application program on the other end uses an active open request a
connection.
• The two TCP software modules communicate to establish and verify
a connection.
• Once the connection is established, the application programs begin
to pass data.
• TCP modules at each end guarantee reliable delivery.
13. Segments, Streams, and Sequence Numbers
TCP views the data as a sequence of octets that it divides into segments.
Usually, each segment travels in a single IP datagram.
TCP uses a specialized sliding window mechanism to solve two
problems: efficient transmission and flow control.
TCP allows the receiver to restrict transmission until it has sufficient
buffer space to accommodate more data.
The sliding window mechanism operates the octet level. A sender keeps
three pointers associated with each connection.
TCP software at each end maintains two windows per connection
for a total of four.
One slides as data is sent, the other as data is
received.
14. Variable Window Size and Flow Control
TCP allows the window size to vary over time. Each ack contains a
window advertisement that specifies how many octets of data the
receiver is prepared to accept.
This provides flow control. The window size may even be zero.
When intermediate machines become overloaded, the condition is
called congestion, and mechanisms to solve the problem are called
congestion control mechanisms.
Solves two independent problems.
• A hand-held PDA communicating with a fast PC may be overrun.
•A mechanism is needed to allow intermediate systems (routers) to
control a source that sends more traffic than the system can tolerate.
15. TCP Segment Format
IP header TCP header TCP data
Sequence number (32 bits)
DATA
20 bytes 20 bytes
0 15 16 31
Source Port Number Destination Port Number
Acknowledgement number (32 bits)
window size
header
length
0 Flags
Options (if any)
TCP checksum urgent pointer
20bytes
16. Port Number:
• A port number identifies the endpoint of a connection.
• A pair <IP address, port number> identifies one
endpoint of a connection.
• Two pairs <client IP address, server port
number> and <server IP address, server port
number> identify a TCP connection.
TCP
IP
Applications
23 10480Ports:
TCP
IP
Applications
7 1680 Ports:
17. Sequence Number (SeqNo):
• Sequence number is 32 bits long.
• So the range of SeqNo is
0 <= SeqNo <= 232 -1 4.3 Gbyte
• Each sequence number identifies a byte in the byte stream
• Initial Sequence Number (ISN) of a connection is set during
connection establishment
Acknowledgement Number (AckNo):
• Acknowledgements are piggybacked, I.e a segment from A -> B
can contain an acknowledgement for a data sent in the B -> A
direction
18. 18
• A hosts uses the AckNo field to send acknowledgements. (If a host
sends an AckNo in a segment it sets the “ACK flag”)
• The AckNo contains the next SeqNo that a hosts wants to receive
Example: The acknowledgement for a segment with
sequence numbers 0-1500 is AckNo=1501
• TCP uses the sliding window flow protocol (see CS 457) to
regulate the flow of traffic from sender to receiver
• TCP uses the following variation of sliding window:
ono NACKs (Negative ACKnowledgement)
oonly cumulative ACKs
19. 19
Header Length ( 4bits):
• Length of header in 32-bit words
• Note that TCP header has variable length (with minimum 20
bytes)
Flag bits:
• URG: Urgent pointer is valid
oIf the bit is set, the following bytes contain an urgent message in the
range:
oSeqNo <= urgent message <= SeqNo+urgent pointer
• ACK: Acknowledgement Number is valid
• PSH: PUSH Flag
oNotification from sender to the receiver that the receiver should pass all
data that it has to the application.
oNormally set by sender when the sender’s buffer is empty
20. • RST: Reset the connection
oThe flag causes the receiver to reset the connection
oReceiver of a RST terminates the connection and indicates
higher layer application about the reset
• SYN: Synchronize sequence numbers
oSent in the first packet when initiating a connection
• FIN: Sender is finished with sending
oUsed for closing a connection
oBoth sides of a connection must send a FIN
TCP Checksum:
• TCP checksum covers over both TCP header and TCP data (also
covers some parts of the IP header)
21. 21
• Window Size:
• Each side of the connection advertises the window size
• Window size is the maximum number of bytes that a receiver can
accept.
• Maximum window size is 216-1= 65535 bytes
• Urgent Pointer:
• Only valid if URG flag is set
22. • Options:
End of
Options kind=0
1 byte
NOP
(no operation) kind=1
1 byte
Maximum
Segment Size
kind=2
1 byte
len=4
1 byte
maximum
segment size
2 bytes
Window Scale
Factor kind=3
1 byte
len=3
1 byte
shift count
1 byte
Timestamp kind=8
1 byte
len=10
1 byte
timestamp value
4 bytes
timestamp echo reply
4 bytes
23. 23
• Options:
• NOP is used to pad TCP header to multiples of 4 bytes
• Maximum Segment Size
• Window Scale Options
oIncreases the TCP window from 16 to 32 bits, I.e., the
window size is interpreted differently
oThis option can only be used in the SYN segment (first
segment) during connection establishment time
• Timestamp Option
oCan be used for roundtrip measurements
24. Connection Setup
• The client sends a synchronisation (SYN) packet
specifying
• The port number of the server
• The clients initial sequence number
• The server responds with its own SYN segment,
which specifies its initial sequence number (ISN).
The server also acknowledges the clients SYN. This
segment is called a SYN,ACK.
• The client must acknowledge the SYN from the
server by acking the server’s ISN.
• This is called a three way handshake
• Host A performs an Active Open
• Host B performs a Passive Open
• Both sides agree on initial sequence numbers
• Both sides advertise initial window sizes
• Both sides are now ready to transfer data
send
SYN
seq=x
receive SYN
segment
send SYN
seq=y,
ACK x+1
receive
SYN +ACK
segment
send ACK
y+1
receive ACK
segment
host A host B
25. Connection Closure
• It takes four segments to terminate a
connection
• Each direction of data flow is closed separately.
• It is possible for a TCP connection to be half closed
• Finish segments are issued as a result of an
application close
• ACKs of FIN segments are issued by TCP
without reference to the application
• Host A performs an active close
• Host B performs a passive close
• FIN of A is ACKed immediately by TCP
• Host B only issues its own FIN when the application
has reacted to receipt of the first FIN, by issuing a
send
FIN
seq=x
receive FIN
segment
receive
FIN +ACK
segment
send ACK
y+1
receive ACK
segment
host A host B
receive ACK
segment
send ACK
x+1
send
FIN seq=y,
ACKx+1
26. TCP State Transitions
• Each TCP connection keeps a record of its state, which allows the
connection to progress through several transitions until closure
• The state transitions facilitate connection set up and termination
• All data transfer takes place within the Established state.
27. Starting Point
Normal transitions for a server
Active open
recv: FIN
recv: ACK
send: FIN
recv: FIN
Normal transitions for a client
State
SYN_RCVD
LISTEN
ESTABLISHED
SYN_SENT
CLOSE_WAIT
LAST_ACK
FIN_WAIT_1
FIN_WAIT_2 TIME_WAIT
Key
Active Close
Passive Close
CLOSED
send: ACK
appl: passive open
Data transfer state
2MSL timeout
Name of the TCP state
appl: transition undertaken when application issues operation
recv: transition undertaken when segment received
send: what is sent for this transition
Passive Open
CLOSING
28. Starting Point
Normal transitions for a server
Active open
recv: FIN send:ACK
recv: ACK
Normal transitions for a client
State
SYN_RCVD
LISTEN
ESTABLISHED
SYN_SENT
CLOSE_WAIT
LAST_ACK
FIN_WAIT_1
FIN_WAIT_2 TIME_WAIT
Key
Active Close
Passive Close
CLOSED
Data transfer state
2MSL timeout
Name of the TCP state
appl: transition undertaken when application issues operation
recv: transition undertaken when segment received
send: what is sent for this transition
CLOSING
29. Starting Point
Normal transitions for a server
Active open
recv: FIN send:ACK
recv: ACK
send: FIN
recv: FIN
recv: ACK
Normal transitions for a client
State
SYN_RCVD
LISTEN
ESTABLISHED
SYN_SENT
CLOSE_WAIT
LAST_ACK
FIN_WAIT_1
FIN_WAIT_2 TIME_WAIT
Key
Active Close
Passive Close
CLOSED
send: ACK
appl: passive open
Data transfer state
2MSL timeout
Name of the TCP state
appl: transition undertaken when application issues operation
recv: transition undertaken when segment received
send: what is sent for this transition
Passive Open
CLOSING
30. Starting Point
Normal transitions for a server
simultaneous open
send: SYN,ACK
recv: SYN
Active open
simultaneous close
recv: FIN send:ACK
recv: FIN
send: ACK
recv: ACK
send: FIN
recv: FIN
send: FIN
recv: ACK recv: ACK
Normal transitions for a client
State
SYN_RCVD
LISTEN
ESTABLISHED
SYN_SENT
CLOSE_WAIT
LAST_ACK
CLOSINGFIN_WAIT_1
FIN_WAIT_2 TIME_WAIT
Key
Active Close
Passive Close
TCP State Transitions
CLOSED
send: ACK
appl: passive open
appl: close
Data transfer state
2MSL timeout
appl: close
or timeout
Name of the TCP state
appl: transition undertaken when application issues operation
recv: transition undertaken when segment received
send: what is sent for this transition
Passive Open