This document discusses internetworking and the Internet Protocol version 4 (IPv4). It covers key topics such as:
- IPv4 uses datagram packets that are independently routed and can be fragmented. Each packet contains a header with fields for source/destination addresses, protocol type, and more.
- IPv4 provides unreliable, best-effort delivery that must be paired with TCP for reliability. It positions IP as the network layer in the TCP/IP protocol suite.
- The header fields like time-to-live, identification, and flags support functions like limiting packet lifetime, reassembling fragmented packets, and indicating last fragments. Fragmentation allows transmission of packets larger than the MTU.
-
Evaluation of the Medical Image Compression using Wavelet Packet Transform an...IJECEIAES
Wavelet transforms and wavelet packets are widely imposed in the analysis and resolution of problems related to science and technical engineering. Decomposition wavelet packet allows several frequency bands according to various levels of resolutions. We apply this transform (PWT) coupled with the SPIHT coder to reduce the limitations of conventional wavelet filter bank. The results obtained using the applied algorithm, are very satisfactory and encouraging compared to many of the best coders cited in the literature and show a visual and numerical superiority over conventional methods. These the promising results are confirmed by visual evaluation parameters (PSNR, MSSIM and VIF).
Performance Comparison of FFT, DHT and DCT Based OFDM Systems with BPSK as A ...paperpublications3
Abstract: Today, OFDM has grown to be the most popular communication system in high-speed communications. OFDM is becoming the chosen modulation technique for wireless communications. OFDM can provide large data rates with sufficient robustness to radio channel impairments. Different type of transform techniques such as Discrete Hartley transform (DHT), Discrete Cosine Transform (DCT), Fast Fourier Transform (FFT) are used to perform the modulation and demodulation operations for the OFDM system. In this paper these three transforms are used in OFDM and study the comparison between these different transforms techniques used in OFDM system based on Bit Error Rate (BER) performances.
Evaluation of the Medical Image Compression using Wavelet Packet Transform an...IJECEIAES
Wavelet transforms and wavelet packets are widely imposed in the analysis and resolution of problems related to science and technical engineering. Decomposition wavelet packet allows several frequency bands according to various levels of resolutions. We apply this transform (PWT) coupled with the SPIHT coder to reduce the limitations of conventional wavelet filter bank. The results obtained using the applied algorithm, are very satisfactory and encouraging compared to many of the best coders cited in the literature and show a visual and numerical superiority over conventional methods. These the promising results are confirmed by visual evaluation parameters (PSNR, MSSIM and VIF).
Performance Comparison of FFT, DHT and DCT Based OFDM Systems with BPSK as A ...paperpublications3
Abstract: Today, OFDM has grown to be the most popular communication system in high-speed communications. OFDM is becoming the chosen modulation technique for wireless communications. OFDM can provide large data rates with sufficient robustness to radio channel impairments. Different type of transform techniques such as Discrete Hartley transform (DHT), Discrete Cosine Transform (DCT), Fast Fourier Transform (FFT) are used to perform the modulation and demodulation operations for the OFDM system. In this paper these three transforms are used in OFDM and study the comparison between these different transforms techniques used in OFDM system based on Bit Error Rate (BER) performances.
A Subspace Method for Blind Channel Estimation in CP-free OFDM SystemsCSCJournals
In this paper, a subspace method is proposed for blind channel estimation in orthogonal frequency-division multiplexing (OFDM) systems over time-dispersive channel. The proposed method does not require a cyclic prefix (CP) and thus leading to higher spectral efficiency. By exploiting the block Toeplitz structure of the channel matrix, the proposed blind estimation method performs satisfactorily with very few received OFDM blocks. Numerical simulations demonstrate the superior performance of the proposed algorithm over methods reported earlier in the literature.
Improving The Performance of Viterbi Decoder using Window System IJECEIAES
An efficient Viterbi decoder is introduced in this paper; it is called Viterbi decoder with window system. The simulation results, over Gaussian channels, are performed from rate 1/2, 1/3 and 2/3 joined to TCM encoder with memory in order of 2, 3. These results show that the proposed scheme outperforms the classical Viterbi by a gain of 1 dB. On the other hand, we propose a function called RSCPOLY2TRELLIS, for recursive systematic convolutional (RSC) encoder which creates the trellis structure of a recursive systematic convolutional encoder from the matrix “H”. Moreover, we present a comparison between the decoding algorithms of the TCM encoder like Viterbi soft and hard, and the variants of the MAP decoder known as BCJR or forward-backward algorithm which is very performant in decoding TCM, but depends on the size of the code, the memory, and the CPU requirements of the application.
Real-time DSP Implementation of Audio Crosstalk Cancellation using Mixed Unif...CSCJournals
For high fidelity sound reproduction, it is necessary to use long filter coefficients in audio crosstalk cancellation. To implement these long filters on real-time DSP processors, conventional overlap save technique suffers from more computational power as well as processing delay. To overcome these technical problems, mixed uniform partitioned convolution technique is proposed. This method is derived by combining uniform partitioned convolution with mixed filtering technique. With the proposed method, it is possible to perform audio crosstalk cancellation even at the order of ten thousand filter taps with less computations and short processing delay. The proposed technique was implemented on 32-bit floating point DSP processor and design was provided with efficient memory management to achieve optimization in computational complexity. The computational comparison of this method with conventional methods shows that the proposed technique is very efficient for long filters
These slides cover a topic on Wave Division Multiplexing in Data Communication. All the slides are explained in a very simple manner. It is useful for engineering students & also for the candidates who want to master data communication & computer networking.
Study of the operational SNR while constructing polar codes IJECEIAES
Channel coding is commonly based on protecting information to be communicated across an unreliable medium, by adding patterns of redundancy into the transmission path. Also referred to as forward error control coding (FECC), the technique is widely used to enable correcting or at least detecting bit errors in digital communication systems. In this paper we study an original FECC known as polar coding which has proven to meet the typical use cases of the next generation mobile standard. This work is motivated by the suitability of polar codes for the new coming wireless era. Hence, we investigate the performance of polar codes in terms of bit error rate (BER) for several codeword lengths and code rates. We first perform a discrete search to find the best operational signal-to-noise ratio (SNR) at two different code rates, while varying the blocklength. We find in our extensive simulations that the BER becomes more sensitive to operational SNR (OSNR) as long as we increase the blocklength and code rate. Finally, we note that increasing blocklength achieves an SNR gain, while increasing code rate changes the OSNR domain. This trade-off sorted out must be taken into consideration while designing polar codes for high-throughput application.
Iterative Soft Decision Based Complex K-best MIMO DecoderCSCJournals
This paper presents an iterative soft decision based complex multiple input multiple output (MIMO) decoding algorithm, which reduces the complexity of Maximum Likelihood (ML) detector. We develop a novel iterative complex K-best decoder exploiting the techniques of lattice reduction for 8×8 MIMO. Besides list size, a new adjustable variable has been introduced in order to control the on-demand child expansion. Following this method, we obtain 6.9 to 8.0 dB improvement over real domain K-best decoder and 1.4 to 2.5 dB better performance compared to iterative conventional complex decoder for 4th iteration and 64-QAM modulation scheme. We also demonstrate the significance of new parameter on bit error rate. The proposed decoder not only increases the performance, but also reduces the computational complexity to a certain level.
Dear students get fully solved assignments
Send your semester & Specialization name to our mail id :
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IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Along with idling and contention, communication is a major overhead in parallel programs.
The cost of communication is dependent on a variety of features including the programming model semantics, the network topology, data handling and routing, and associated software protocols.
A Subspace Method for Blind Channel Estimation in CP-free OFDM SystemsCSCJournals
In this paper, a subspace method is proposed for blind channel estimation in orthogonal frequency-division multiplexing (OFDM) systems over time-dispersive channel. The proposed method does not require a cyclic prefix (CP) and thus leading to higher spectral efficiency. By exploiting the block Toeplitz structure of the channel matrix, the proposed blind estimation method performs satisfactorily with very few received OFDM blocks. Numerical simulations demonstrate the superior performance of the proposed algorithm over methods reported earlier in the literature.
Improving The Performance of Viterbi Decoder using Window System IJECEIAES
An efficient Viterbi decoder is introduced in this paper; it is called Viterbi decoder with window system. The simulation results, over Gaussian channels, are performed from rate 1/2, 1/3 and 2/3 joined to TCM encoder with memory in order of 2, 3. These results show that the proposed scheme outperforms the classical Viterbi by a gain of 1 dB. On the other hand, we propose a function called RSCPOLY2TRELLIS, for recursive systematic convolutional (RSC) encoder which creates the trellis structure of a recursive systematic convolutional encoder from the matrix “H”. Moreover, we present a comparison between the decoding algorithms of the TCM encoder like Viterbi soft and hard, and the variants of the MAP decoder known as BCJR or forward-backward algorithm which is very performant in decoding TCM, but depends on the size of the code, the memory, and the CPU requirements of the application.
Real-time DSP Implementation of Audio Crosstalk Cancellation using Mixed Unif...CSCJournals
For high fidelity sound reproduction, it is necessary to use long filter coefficients in audio crosstalk cancellation. To implement these long filters on real-time DSP processors, conventional overlap save technique suffers from more computational power as well as processing delay. To overcome these technical problems, mixed uniform partitioned convolution technique is proposed. This method is derived by combining uniform partitioned convolution with mixed filtering technique. With the proposed method, it is possible to perform audio crosstalk cancellation even at the order of ten thousand filter taps with less computations and short processing delay. The proposed technique was implemented on 32-bit floating point DSP processor and design was provided with efficient memory management to achieve optimization in computational complexity. The computational comparison of this method with conventional methods shows that the proposed technique is very efficient for long filters
These slides cover a topic on Wave Division Multiplexing in Data Communication. All the slides are explained in a very simple manner. It is useful for engineering students & also for the candidates who want to master data communication & computer networking.
Study of the operational SNR while constructing polar codes IJECEIAES
Channel coding is commonly based on protecting information to be communicated across an unreliable medium, by adding patterns of redundancy into the transmission path. Also referred to as forward error control coding (FECC), the technique is widely used to enable correcting or at least detecting bit errors in digital communication systems. In this paper we study an original FECC known as polar coding which has proven to meet the typical use cases of the next generation mobile standard. This work is motivated by the suitability of polar codes for the new coming wireless era. Hence, we investigate the performance of polar codes in terms of bit error rate (BER) for several codeword lengths and code rates. We first perform a discrete search to find the best operational signal-to-noise ratio (SNR) at two different code rates, while varying the blocklength. We find in our extensive simulations that the BER becomes more sensitive to operational SNR (OSNR) as long as we increase the blocklength and code rate. Finally, we note that increasing blocklength achieves an SNR gain, while increasing code rate changes the OSNR domain. This trade-off sorted out must be taken into consideration while designing polar codes for high-throughput application.
Iterative Soft Decision Based Complex K-best MIMO DecoderCSCJournals
This paper presents an iterative soft decision based complex multiple input multiple output (MIMO) decoding algorithm, which reduces the complexity of Maximum Likelihood (ML) detector. We develop a novel iterative complex K-best decoder exploiting the techniques of lattice reduction for 8×8 MIMO. Besides list size, a new adjustable variable has been introduced in order to control the on-demand child expansion. Following this method, we obtain 6.9 to 8.0 dB improvement over real domain K-best decoder and 1.4 to 2.5 dB better performance compared to iterative conventional complex decoder for 4th iteration and 64-QAM modulation scheme. We also demonstrate the significance of new parameter on bit error rate. The proposed decoder not only increases the performance, but also reduces the computational complexity to a certain level.
Dear students get fully solved assignments
Send your semester & Specialization name to our mail id :
“ help.mbaassignments@gmail.com ”
or
Call us at : 08263069601
(Prefer mailing. Call in emergency )
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Along with idling and contention, communication is a major overhead in parallel programs.
The cost of communication is dependent on a variety of features including the programming model semantics, the network topology, data handling and routing, and associated software protocols.
IntroductionTransport LayerTransport Layer forms the bas.docxmariuse18nolet
Introduction:
Transport Layer:
Transport Layer forms the base of the internet which is included in both OSI model as well as TCP/IP model. Its functionality differs in both the models providing appropriate services like flow control, connection-oriented data stream support and multiplexing. .
The transport layer provides endwise communication services for applications within a layered approach of network components.
Segmentation is the process of dividing the data stream or the contents of message into packets.
Whenever a command is issued in a TCP/IP application layer protocol, a sequence of events gets initiated. The message or command first passes through the stack TCP/IP protocol stack in a personal system. It then passes across the network media and protocols on a distant or remote system. At every layer the protocols on the sending host adds information to the actual data and also interacts with the peers on the receiving host.
Security using Data Encapsulation:
Information is transferred across a network in the form of packets. Every packet consists of a header with the address of sending and receiving systems and a body with data to be transferred. The process in which a protocol on the sending host adds data to the packet header is named data encapsulation. Every layer has a different term for the altered packet, like a packet on a Transport layer is termed as TCP segment, IP diagram in Internet layer, Frame in data link layer and physical Network layer.
Protocols in Transport Layer:
The most commonly used transport protocol is the Transmission Control Protocol (TCP). It is used for connection-oriented transmission(s), whereas the other connectionless i.e. User
Datagram Protocol (UDP) is used for simpler messaging transmission applications.
TCP is the more complex protocol, due to its design which incorporates reliable transmission and data streaming services.
Other protocol examples in this group are the Datagram Congestion Control Protocol (DCCP) and the Stream Control Transmission Protocol (SCTP).
Packet - Packaging the Transport Layer:
With Transport layer segment or datagram the network can deliver data/information to the destination host.
The IPv4 encapsulation remains in place from the time the packet leaves the Network layer of the originating host until it arrives at the Network layer of the destination host.
The process of encapsulating data by layer enables the services at the different layers to develop and scale without affecting other layers.
This means that transport layer segments can be readily packaged by existing Network layer protocols, such as IPv4 and IPv6 or by any new protocol that might be developed in the future.
Routers can implement these different Network layer protocols to operate concurrently over a network to and from the same or different hosts.
The routing performed by these intermediary devices only considers the contents of the packet header that encapsulates the segment. In .
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!
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
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
A Strategic Approach: GenAI in EducationPeter 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.
Francesca Gottschalk - How can education support child empowerment.pptxEduSkills OECD
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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.
Introduction to AI for Nonprofits with Tapp NetworkTechSoup
Dive into the world of AI! Experts Jon Hill and Tareq Monaur will guide you through AI's role in enhancing nonprofit websites and basic marketing strategies, making it easy to understand and apply.
2. 20.2
INTERNETWORKINGINTERNETWORKING
We now discuss internetworking _ connectingWe now discuss internetworking _ connecting
networks together to make an internetwork or annetworks together to make an internetwork or an
internet.internet.
6. 20.6
Switching at the network layer in the
Internet uses the datagram approach to
packet switching. In a datagram
network, each packet is treated
independently of others, even if it is a
part of a multipacket transmission.
Packets in this approach are normally
referred to as datagrams.
Note
7. 20.7
Communication at the network layer in
the Internet is connectionless. The
reason for this is due to the
heterogeneous nature of the Internet.
Note
8. 20.8
IPv4IPv4
• The Internet Protocol version 4 (The Internet Protocol version 4 (IPv4IPv4) is the) is the
delivery mechanism used by the TCP/IP protocols.delivery mechanism used by the TCP/IP protocols.
• It is an unreliable – aIt is an unreliable – a best-effort deliverybest-effort delivery service.service.
• If reliability is important, then it must be pairedIf reliability is important, then it must be paired
withwith TCP.TCP.
12. 20.12
• Differentiated Services or DiffServ is a computer
networking architecture that specifies a simple, scalable
and coarse-grained mechanism for classifying, managing
network traffic and providing Quality of Service (QoS)
guarantees on modern IP networks.
• DiffServ can, for example, be used to provide low-
latency, low-loss service to critical network traffic such as
voice or video while providing simple best-effort traffic
guarantees to non-critical services such as web traffic or
file transfers.
• DiffServ uses the 6-bit Differentiated Services Code
Point (DSCP) field in the header of IP packets for packet
classification purposes.
13. 20.13
• In theory, a network could have up to 64 (i.e. 26
)
different traffic classes using different markings in the
DSCP. The DiffServ RFCs recommend, but do not require,
certain encodings.
• This gives a network operator great flexibility in
defining traffic classes. In practice, however, most
networks use the following commonly-defined Per-Hop
Behaviors:
–Default PHB—which is typically best-effort traffic
–Assured Forwarding (AF) PHB— which gives assurance of
delivery under conditions
–Expedited Forwarding (EF) PHB—dedicated to low-loss,
low-latency traffic
14. 20.14
The total length field defines the total
length of the datagram including the
header. Required such that can
differentiate from the padding.
Note
What is this ?
16. 20.16
• Time to live (TTL) (8 bits) - Limits the number of
routers the datagram can pass through. Usually
set to 32 or 64 (some even recommend 128).
Every time the datagram passes through a router
this value is decremented by a value of one or
more. This is to keep the datagram from circulating
in an infinite loop forever.
• Protocol (8 bits) - It identifies the protocol
whose data is encapsulated in the datagram.
• Source & Destination IP Address – Self-
explanatory.
18. 20.18
An IPv4 packet has arrived with the first 8 bits as shown:
01000010
The receiver discards the packet. Why?
Solution
There is an error in this packet. The 4 leftmost bits (0100)
show the version, which is correct. The next 4 bits (0010)
show an invalid header length (2 × 4 = 8). The minimum
number of bytes in the header must be 20. The packet has
been corrupted in transmission.
Example 1
19. 20.19
In an IPv4 packet, the value of HLEN is 1000 in binary.
How many bytes of options are being carried by this
packet?
Solution
The HLEN value is 8, which means the total number of
bytes in the header is 8 × 4, or 32 bytes. The first 20 bytes
are the base header, the next 12 bytes are the options.
Example 2
20. 20.20
In an IPv4 packet, the value of HLEN is 5, and the value
of the total length field is 0x0028. How many bytes of
data are being carried by this packet?
Solution
The HLEN value is 5, which means the total number of
bytes in the header is 5 × 4, or 20 bytes (no options). The
total length is 40 bytes, which means the packet is
carrying 20 bytes of data (40 20).−
Example 3
21. 20.21
An IPv4 packet has arrived with the first few hexadecimal
digits as shown.
0x45000028000100000102 . . .
How many hops can this packet travel before being
dropped? The data belong to what upper-layer protocol?
Solution
To find the time-to-live field, we skip 8 bytes. The time-to-
live field is the ninth byte, which is 01. This means the
packet can travel only one hop. The protocol field is the
next byte (02), which means that the upper-layer protocol
is IGMP.
Example 4
22. 20.22
Maximum Transmission Unit (MTU)
• IP packets larger than the
MTU must go through IP
fragmentation procedures.
MTUs for some networks
23. 20.23
• Fragmentation related fields:
•Identification - Uniquely identifies each datagram. This is used
to re-assemble the datagram. Each fragment of the datagram
contains this same unique number.
• Flags:
— Bit 0 - reserved.
— Bit 1 - The do not fragment bit. A value of 1 means the packet
should not be fragmented while a 0 means it may be
fragmented.
— Bit 2 - The more fragment bit. This value is set on all fragments
except the last one since a value of 0 means this is the last
fragment.
• Fragment offset - The offset in 8 byte units of this fragment
from the beginning of the original datagram (8191 x 8 = 65528).
26. 20.26
A packet has arrived with an M bit value of 0. Is this the
first fragment, the last fragment, or a middle fragment?
Do we know if the packet was fragmented?
Solution
If the M bit is 0, it means that there are no more
fragments; the fragment is the last one. However, we
cannot say if the original packet was fragmented or not. A
non-fragmented packet is considered the last fragment.
Example 5
27. 20.27
A packet has arrived with an M bit value of 1. Is this the
first fragment, the last fragment, or a middle fragment?
Do we know if the packet was fragmented?
Solution
If the M bit is 1, it means that there is at least one more
fragment. This fragment can be the first one or a middle
one, but not the last one. We don’t know if it is the first
one or a middle one; we need more information (the
value of the fragmentation offset).
Example 6
28. 20.28
A packet has arrived with an M bit value of 1 and a
fragmentation offset value of 0. Is this the first fragment,
the last fragment, or a middle fragment?
Solution
Because the M bit is 1, it is either the first fragment or a
middle one. Because the offset value is 0, it is the first
fragment.
Example 7
29. 20.29
A packet has arrived in which the offset value is 100.
What is the number of the first byte? Do we know the
number of the last byte?
Solution
To find the number of the first byte, we multiply the offset
value by 8. This means that the first byte number is 800.
We cannot determine the number of the last byte unless
we know the length.
Example 8
30. 20.30
A packet has arrived in which the offset value is 100, the
value of HLEN is 5, and the value of the total length field
is 100. What are the numbers of the first byte and the last
byte?
Solution
The first byte number is 100 × 8 = 800. The total length is
100 bytes, and the header length is 20 bytes (5 × 4), which
means that there are 80 bytes in this datagram. If the first
byte number is 800, the last byte number must be 879.
Example 9
31. 20.31
Figure shows an example of a checksum calculation for
an IPv4 header without options. The header is divided
into 16-bit sections. All the sections are added and the
sum is complemented. The result is inserted in the
checksum field.
Example 10