The ISO/OSI model defines seven layers for network communication:
1. The physical layer transmits raw bits over a communication channel.
2. The data link layer handles framing and error checking.
3. The network layer handles routing and logical addressing.
4. The transport layer ensures reliable delivery of data segments.
5. The session layer allows for bidirectional communication sessions.
6. The presentation layer handles data formatting and encoding.
7. The application layer interacts directly with software applications.
Each layer only communicates with the layer directly above and below it, with the physical layer interacting with the actual network and the application layer interacting with end user processes.
This document provides information about getting fully solved assignments for SMU BBA Spring 2014. It instructs students to send their semester and specialization name to the email address "help.mbaassignments@gmail.com" or call the phone number 08263069601 to obtain the assignments. The document then provides sample answers to 6 questions related to subjects like computer networks, ALOHA protocols, data link layer, shortest path routing algorithm, session layer design issues, and recursive vs iterative DNS queries.
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 )
This paper summarizes and improves upon the NTBCBT mutual exclusion algorithm. The NTBCBT algorithm has problems related to safety, liveness, and scheduling when nodes request access to a critical resource. The paper proposes an improved algorithm called PBCBT that addresses these weaknesses. PBCBT requires only 3log(N) messages per access to the critical section, compared to 4log(N) for NTBCBT. It also has an improved synchronization delay of 2log(N) messages compared to 3log(N) for NTBCBT. The improvements are achieved through removing unnecessary messages, reorganizing node instructions, and prioritizing requests based on timestamps.
Message passing involves processes communicating by exchanging fixed or variable sized messages without shared variables. It can be used for inter-process communication within a single computer or across a network. Message passing may be blocking, where a sending process blocks until the message is received, or non-blocking. Key aspects of message passing include the communication primitives used, whether messages are sent directly or indirectly through mailboxes, and how communication links between processes are established and their properties.
This document discusses inter-process communication (IPC) and its various models and mechanisms. It describes two main IPC models: shared memory and message passing. Shared memory allows processes to exchange information by reading and writing to a shared memory region, while message passing involves processes exchanging messages. The document further discusses different ways of implementing message passing links, including direct vs indirect communication, synchronous vs asynchronous communication, and zero, bounded, and unbounded buffering approaches.
This document summarizes a research paper that proposes a defense system for peer-to-peer (P2P) content distribution networks using network coding. The system aims to (1) detect polluted data blocks early, (2) identify the exact location of colluding malicious peers, and (3) reduce verification costs to prevent propagation of malicious blocks. It introduces mechanisms for peers to cooperate in both distributing content and protecting against malicious peers by alerting others about detected malicious blocks. The proposed system introduces less communication and computation overhead than other state-of-the-art defense schemes for P2P networks.
The document provides an overview of the seven-layer OSI model for computer networking. It describes each layer and its functions, including the physical, data link, network, transport, session, presentation and application layers. The physical layer defines cable specifications, the data link layer provides addressing and error detection, and the network layer enables routing between different networks using logical addresses. Higher layers include the transport layer for reliable data transmission, and the session, presentation and application layers for establishing communication between applications and presenting data to the end user.
This document provides information about getting fully solved assignments for SMU BBA Spring 2014. It instructs students to send their semester and specialization name to the email address "help.mbaassignments@gmail.com" or call the phone number 08263069601 to obtain the assignments. The document then provides sample answers to 6 questions related to subjects like computer networks, ALOHA protocols, data link layer, shortest path routing algorithm, session layer design issues, and recursive vs iterative DNS queries.
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 )
This paper summarizes and improves upon the NTBCBT mutual exclusion algorithm. The NTBCBT algorithm has problems related to safety, liveness, and scheduling when nodes request access to a critical resource. The paper proposes an improved algorithm called PBCBT that addresses these weaknesses. PBCBT requires only 3log(N) messages per access to the critical section, compared to 4log(N) for NTBCBT. It also has an improved synchronization delay of 2log(N) messages compared to 3log(N) for NTBCBT. The improvements are achieved through removing unnecessary messages, reorganizing node instructions, and prioritizing requests based on timestamps.
Message passing involves processes communicating by exchanging fixed or variable sized messages without shared variables. It can be used for inter-process communication within a single computer or across a network. Message passing may be blocking, where a sending process blocks until the message is received, or non-blocking. Key aspects of message passing include the communication primitives used, whether messages are sent directly or indirectly through mailboxes, and how communication links between processes are established and their properties.
This document discusses inter-process communication (IPC) and its various models and mechanisms. It describes two main IPC models: shared memory and message passing. Shared memory allows processes to exchange information by reading and writing to a shared memory region, while message passing involves processes exchanging messages. The document further discusses different ways of implementing message passing links, including direct vs indirect communication, synchronous vs asynchronous communication, and zero, bounded, and unbounded buffering approaches.
This document summarizes a research paper that proposes a defense system for peer-to-peer (P2P) content distribution networks using network coding. The system aims to (1) detect polluted data blocks early, (2) identify the exact location of colluding malicious peers, and (3) reduce verification costs to prevent propagation of malicious blocks. It introduces mechanisms for peers to cooperate in both distributing content and protecting against malicious peers by alerting others about detected malicious blocks. The proposed system introduces less communication and computation overhead than other state-of-the-art defense schemes for P2P networks.
The document provides an overview of the seven-layer OSI model for computer networking. It describes each layer and its functions, including the physical, data link, network, transport, session, presentation and application layers. The physical layer defines cable specifications, the data link layer provides addressing and error detection, and the network layer enables routing between different networks using logical addresses. Higher layers include the transport layer for reliable data transmission, and the session, presentation and application layers for establishing communication between applications and presenting data to the end user.
An Effective Privacy-Preserving Data Coding in Peer-To-Peer NetworkIJCNCJournal
Coding Opportunistically (COPE) is a simple but very effective data coding mechanism in the wireless network.
However, COPE leaves risks for attackers easily getting the private information saved in the packets,
when they move through the network to their destination nodes. Hence, a lightweight cryptographic approach,
namely SCOPE, was proposed to consolidate COPE against the honest-but-curious and malicious
attacks. Honest-but-curious attack serves adversaries who accurately obey the protocol but try to learn as
much private information as possible for their curiosity. Additionally, this kind of attack is not destructive
consequently. However, it may leave the backdoor for the more dangerous attacks carrying catastrophes
to the system. Malicious attack tries to learn not only the private information but also modifies the packet
on harmful purposes. To cope with this issue, in this work, a lightweight cryptographic approach improves
COPE, namely SCOPE, that is defensive to the both attacks. The private information in the COPE packet
are encrypted by Elliptic Curve Cryptography (ECC), and an additional information is inserted into SCOPE
packets served for the authentication process using the lightweight hash Elliptic Curve Digital Signature Algorithm
(ECDSA). We then prove our new protocol is still guaranteed to be a secure method of data coding,
and to be light to effectively operate in the peer-to-peer wireless network.
Elgamal signature for content distribution with network codingijwmn
This document proposes a scheme that uses ElGamal signature in network coding to enhance security. Network coding allows nodes to generate output packets as linear combinations of input packets. However, this makes the network vulnerable to pollution attacks where malicious nodes can insert corrupted packets. The proposed scheme signs data packets with ElGamal signatures. When nodes receive packets, they can verify the signatures' validity to check for corrupted packets without decoding. The scheme exploits the linearity of network coding and allows nodes to easily check packet integrity. An example is provided to demonstrate how the ElGamal signature scheme would work in the context of network coding for content distribution.
This document summarizes a research paper on finding alternate paths in wireless networks using fast rerouting. It discusses how wireless ad hoc networks are self-configuring and nodes can join networks anywhere. Existing routing techniques have delays when links fail. The paper proposes calculating alternate paths instantly when a node fails to reduce packet loss. It would find a new path from the source to destination much faster than existing systems. When a node fails or does not respond, it would choose the next closest responding node and reroute packets along the new path immediately, without waiting for routing tables to update. This provides faster rerouting and recovery from link failures in wireless networks.
Research on word representation models, word embeddings, has gained a lot of attention in the recent years thanks to Word2Vec by Mikolov et al. The main purpose of this work is to validate previously proposed experiments for the English language and then trying to figure out if it is possibile to reproduce the same accuracy and performance with the Italian language.
OSI Model of networking. Purpose of a protocol. Description of various layers of the OSI model. Function of each layer is explained in detail.
Video on OSI Model is here: https://youtu.be/b-JU9aWdoP8
with exam questions
REDUCED COMPLEXITY QUASI-CYCLIC LDPC ENCODER FOR IEEE 802.11N VLSICS Design
In this paper, we present a low complexity Quasi-cyclic -low-density-parity-check (QC-LDPC) encoder hardware based on Richardson and Urbanke lower- triangular algorithm for IEEE 802.11n wireless LAN Standard for 648 block length and 1/2 code rate. The LDPC encoder hardware implementation works at 301.433MHz and it can process 12.12 Gbps throughput. We apply the concept of multiplication by constant matrices in GF(2) due to which hardware required is also optimized. Proposed architecture of QC-LDPC encoder will be compatible for high-speed applications. This hardwired architecture is less
complex as it avoids conventionally used block memories and cyclic-shifters.
Universal Network Coding-Based Opportunistic Routing for Unicast1crore projects
IEEE PROJECTS 2015
1 crore projects is a leading Guide for ieee Projects and real time projects Works Provider.
It has been provided Lot of Guidance for Thousands of Students & made them more beneficial in all Technology Training.
Dot Net
DOTNET Project Domain list 2015
1. IEEE based on datamining and knowledge engineering
2. IEEE based on mobile computing
3. IEEE based on networking
4. IEEE based on Image processing
5. IEEE based on Multimedia
6. IEEE based on Network security
7. IEEE based on parallel and distributed systems
Java Project Domain list 2015
1. IEEE based on datamining and knowledge engineering
2. IEEE based on mobile computing
3. IEEE based on networking
4. IEEE based on Image processing
5. IEEE based on Multimedia
6. IEEE based on Network security
7. IEEE based on parallel and distributed systems
ECE IEEE Projects 2015
1. Matlab project
2. Ns2 project
3. Embedded project
4. Robotics project
Eligibility
Final Year students of
1. BSc (C.S)
2. BCA/B.E(C.S)
3. B.Tech IT
4. BE (C.S)
5. MSc (C.S)
6. MSc (IT)
7. MCA
8. MS (IT)
9. ME(ALL)
10. BE(ECE)(EEE)(E&I)
TECHNOLOGY USED AND FOR TRAINING IN
1. DOT NET
2. C sharp
3. ASP
4. VB
5. SQL SERVER
6. JAVA
7. J2EE
8. STRINGS
9. ORACLE
10. VB dotNET
11. EMBEDDED
12. MAT LAB
13. LAB VIEW
14. Multi Sim
CONTACT US
1 CRORE PROJECTS
Door No: 214/215,2nd Floor,
No. 172, Raahat Plaza, (Shopping Mall) ,Arcot Road, Vadapalani, Chennai,
Tamin Nadu, INDIA - 600 026
Email id: 1croreprojects@gmail.com
website:1croreprojects.com
Phone : +91 97518 00789 / +91 72999 51536
A genetic algorithm for constructing broadcast trees with cost and delay cons...IJCNCJournal
We refer to the problem of constructing broadcast trees with cost and delay constraints in the networks as a delay-constrained minimum spanning tree problem in directed networks. Hence it is necessary determining a spanning tree of minimal cost to connect the source node to all nodes subject to delay constraints on broadcast routing. In this paper, we proposed a genetic algorithm for solving broadcast routing by finding the low-cost broadcast tree with minimum cost and delay constraints. In this research we present a genetic algorithm to find the broadcast routing tree of a given network in terms of its links. The algorithm uses the connection matrix of the given network to find the spanning trees and considers the weights of the links to obtain the minimum spanning tree. Our proposed algorithm is able to find a better solution, fast convergence speed and high reliability. The scalability and the performance of the algorithm with increasing number of network nodes are also encouraging.
Applying Deep Learning Machine Translation to Language ServicesYannis Flet-Berliac
Recurrent neural networks (RNNs) have been performing well for learning tasks for several decades now. The most useful benefit they present for this paper is their ability to use contextual information when mapping between input and output sequences.
A deep neural network for machine translation implies the use of a sequence-to-sequence model, consisting of two RNNs: an encoder that processes the input and a decoder that generates the output.
To meaningfully assess the model’s performances, texts from a translation company and thoughts from skilled experts about specialized topics will be tested.
AUTOCONFIGURATION ALGORITHM FOR A MULTIPLE INTERFACES ADHOC NETWORK RUNNING...IJCNC
Network configuration is the assignment of network parameters necessary for a device to integrate the
network, examples being: an IP address, netmask, the IP address of the gateway, etc ... In the case of
Mobile Ad hoc NETworks (MANETs), the connectivity of nodes is highly dynamic and a central
administration or configuration by the user is very difficult. This paper presents an autoconfiguration
solution for ad hoc networks running the widely implemented version of OLSR routing protocol, the 2003
RFC 3626 [1]. This solution is based on an efficient Duplicate Address Detection (DAD) algorithm,
which takes advantage of the genuine optimization of the OLSR routing protocol. The proposed
autoconfiguration algorithm is proved to operate correctly in a multiple interfaces OLSR network.
Securing Group Communication in Partially Distributed SystemsIOSR Journals
This document summarizes an approach for securing group communication in partially distributed systems. The approach divides groups into regions, each with their own Key Distribution Center (KDC). Intra-region communication uses public-key cryptography, while inter-region communication uses a hierarchical key exchange approach involving symmetric keys. Key graphs are used to represent the partial distribution structure, and rekeying strategies are employed when users join or leave groups to dynamically update keys and prevent unauthorized access. The approach aims to provide security properties like authenticity, confidentiality and integrity, while maintaining scalability for distributed systems with changing group membership.
Reggaeton originated as a blending of West Indian music like reggae and dancehall with Latin American genres like salsa and merengue as well as hip hop. While it takes influence from hip hop and Jamaican dancehall, reggaeton has developed its own distinct beat and rhythm. The genre first emerged in Panama as "Spanish reggae," an adapted version of Jamaican reggae, before spreading to Puerto Rico where rappers produced a mix of reggae and hip hop that helped spread the early reggaeton sound. Caribbean migrants working on the Panama Canal in the early 1900s influenced the development of reggaeton in Panama.
The document lists key details about the life and work of American artist Jackson Pollock including some of his major paintings from 1938 to 1953 such as "Hacia el Oeste" and "Number 32", as well as photos of him with other artists from the New York School. It also mentions Pollock's relationship with Peggy Guggenheim who supported his work and a famous quote of his about expressing feelings rather than illustrating them.
This document summarizes the conditions of poverty in America, describing a "second America" where millions live in poverty without jobs or adequate housing, trapped in a "triple ghetto" of race, poverty, and misery. It notes that while America enjoys vast material prosperity, many perishing on "a lonely island of poverty". The civil rights movement aims to address this problem of "two Americas" and make the nation indivisible with liberty and justice for all.
The document discusses three ways of applying CSS: inline, internal, and external. It provides examples of each method and explains their differences. Inline CSS is written directly in HTML tags, internal CSS is defined within the <style> tag in the <head> section, and external CSS has the styles defined in a separate .css file that is linked via the <link> tag. The document also covers various CSS properties for formatting text like font, color, size, alignment; box model properties like margin, padding, border; and CSS selectors like classes and IDs.
The document discusses layered network architecture and the ISO/OSI model. It begins with explaining that layered architecture divides network functionality across different layers, with each layer providing services to the layer above it. It then provides answers to various questions about layered architecture and the ISO/OSI model. Specifically, it summarizes the purpose and functions of different layers like the presentation layer, which performs translation, encryption, and data compression between systems. It also explains concepts like encapsulation, peer-to-peer communication, and how layered architecture enables communication between hosts.
- Data can be analog or digital, with analog being continuous and digital having discrete states. Analog signals are also continuous while digital signals have a limited set of values.
- Periodic analog signals like sine waves can be simple or composite, consisting of multiple sine waves. Nonperiodic signals are commonly used for digital data transmission.
- Digital signals represent information using discrete signal levels that can be encoded as voltages, with more levels allowing more bits to be sent per signal. The required bit rate depends on the data transmission rate and number of bits used per sample or character.
This powerpoint presentation contains quotes from Dr. Martin Luther King Jr. about topics like hope, leadership, darkness and light, freedom, human progress, power, truth and love overcoming evil, judging people by character rather than skin color, and sacrificing physical life for spiritual freedom. The presentation aims to honor Dr. King through sharing his influential words on these important subjects.
The document discusses network models including the OSI model and TCP/IP model. It describes the seven layers of the OSI model and the four layers of the TCP/IP model. For each layer, it provides details on their functions and protocols. It also compares the OSI and TCP/IP models, noting they are both based on layered architectures but that the TCP/IP model combines some layers and better fits existing protocols.
An Effective Privacy-Preserving Data Coding in Peer-To-Peer NetworkIJCNCJournal
Coding Opportunistically (COPE) is a simple but very effective data coding mechanism in the wireless network.
However, COPE leaves risks for attackers easily getting the private information saved in the packets,
when they move through the network to their destination nodes. Hence, a lightweight cryptographic approach,
namely SCOPE, was proposed to consolidate COPE against the honest-but-curious and malicious
attacks. Honest-but-curious attack serves adversaries who accurately obey the protocol but try to learn as
much private information as possible for their curiosity. Additionally, this kind of attack is not destructive
consequently. However, it may leave the backdoor for the more dangerous attacks carrying catastrophes
to the system. Malicious attack tries to learn not only the private information but also modifies the packet
on harmful purposes. To cope with this issue, in this work, a lightweight cryptographic approach improves
COPE, namely SCOPE, that is defensive to the both attacks. The private information in the COPE packet
are encrypted by Elliptic Curve Cryptography (ECC), and an additional information is inserted into SCOPE
packets served for the authentication process using the lightweight hash Elliptic Curve Digital Signature Algorithm
(ECDSA). We then prove our new protocol is still guaranteed to be a secure method of data coding,
and to be light to effectively operate in the peer-to-peer wireless network.
Elgamal signature for content distribution with network codingijwmn
This document proposes a scheme that uses ElGamal signature in network coding to enhance security. Network coding allows nodes to generate output packets as linear combinations of input packets. However, this makes the network vulnerable to pollution attacks where malicious nodes can insert corrupted packets. The proposed scheme signs data packets with ElGamal signatures. When nodes receive packets, they can verify the signatures' validity to check for corrupted packets without decoding. The scheme exploits the linearity of network coding and allows nodes to easily check packet integrity. An example is provided to demonstrate how the ElGamal signature scheme would work in the context of network coding for content distribution.
This document summarizes a research paper on finding alternate paths in wireless networks using fast rerouting. It discusses how wireless ad hoc networks are self-configuring and nodes can join networks anywhere. Existing routing techniques have delays when links fail. The paper proposes calculating alternate paths instantly when a node fails to reduce packet loss. It would find a new path from the source to destination much faster than existing systems. When a node fails or does not respond, it would choose the next closest responding node and reroute packets along the new path immediately, without waiting for routing tables to update. This provides faster rerouting and recovery from link failures in wireless networks.
Research on word representation models, word embeddings, has gained a lot of attention in the recent years thanks to Word2Vec by Mikolov et al. The main purpose of this work is to validate previously proposed experiments for the English language and then trying to figure out if it is possibile to reproduce the same accuracy and performance with the Italian language.
OSI Model of networking. Purpose of a protocol. Description of various layers of the OSI model. Function of each layer is explained in detail.
Video on OSI Model is here: https://youtu.be/b-JU9aWdoP8
with exam questions
REDUCED COMPLEXITY QUASI-CYCLIC LDPC ENCODER FOR IEEE 802.11N VLSICS Design
In this paper, we present a low complexity Quasi-cyclic -low-density-parity-check (QC-LDPC) encoder hardware based on Richardson and Urbanke lower- triangular algorithm for IEEE 802.11n wireless LAN Standard for 648 block length and 1/2 code rate. The LDPC encoder hardware implementation works at 301.433MHz and it can process 12.12 Gbps throughput. We apply the concept of multiplication by constant matrices in GF(2) due to which hardware required is also optimized. Proposed architecture of QC-LDPC encoder will be compatible for high-speed applications. This hardwired architecture is less
complex as it avoids conventionally used block memories and cyclic-shifters.
Universal Network Coding-Based Opportunistic Routing for Unicast1crore projects
IEEE PROJECTS 2015
1 crore projects is a leading Guide for ieee Projects and real time projects Works Provider.
It has been provided Lot of Guidance for Thousands of Students & made them more beneficial in all Technology Training.
Dot Net
DOTNET Project Domain list 2015
1. IEEE based on datamining and knowledge engineering
2. IEEE based on mobile computing
3. IEEE based on networking
4. IEEE based on Image processing
5. IEEE based on Multimedia
6. IEEE based on Network security
7. IEEE based on parallel and distributed systems
Java Project Domain list 2015
1. IEEE based on datamining and knowledge engineering
2. IEEE based on mobile computing
3. IEEE based on networking
4. IEEE based on Image processing
5. IEEE based on Multimedia
6. IEEE based on Network security
7. IEEE based on parallel and distributed systems
ECE IEEE Projects 2015
1. Matlab project
2. Ns2 project
3. Embedded project
4. Robotics project
Eligibility
Final Year students of
1. BSc (C.S)
2. BCA/B.E(C.S)
3. B.Tech IT
4. BE (C.S)
5. MSc (C.S)
6. MSc (IT)
7. MCA
8. MS (IT)
9. ME(ALL)
10. BE(ECE)(EEE)(E&I)
TECHNOLOGY USED AND FOR TRAINING IN
1. DOT NET
2. C sharp
3. ASP
4. VB
5. SQL SERVER
6. JAVA
7. J2EE
8. STRINGS
9. ORACLE
10. VB dotNET
11. EMBEDDED
12. MAT LAB
13. LAB VIEW
14. Multi Sim
CONTACT US
1 CRORE PROJECTS
Door No: 214/215,2nd Floor,
No. 172, Raahat Plaza, (Shopping Mall) ,Arcot Road, Vadapalani, Chennai,
Tamin Nadu, INDIA - 600 026
Email id: 1croreprojects@gmail.com
website:1croreprojects.com
Phone : +91 97518 00789 / +91 72999 51536
A genetic algorithm for constructing broadcast trees with cost and delay cons...IJCNCJournal
We refer to the problem of constructing broadcast trees with cost and delay constraints in the networks as a delay-constrained minimum spanning tree problem in directed networks. Hence it is necessary determining a spanning tree of minimal cost to connect the source node to all nodes subject to delay constraints on broadcast routing. In this paper, we proposed a genetic algorithm for solving broadcast routing by finding the low-cost broadcast tree with minimum cost and delay constraints. In this research we present a genetic algorithm to find the broadcast routing tree of a given network in terms of its links. The algorithm uses the connection matrix of the given network to find the spanning trees and considers the weights of the links to obtain the minimum spanning tree. Our proposed algorithm is able to find a better solution, fast convergence speed and high reliability. The scalability and the performance of the algorithm with increasing number of network nodes are also encouraging.
Applying Deep Learning Machine Translation to Language ServicesYannis Flet-Berliac
Recurrent neural networks (RNNs) have been performing well for learning tasks for several decades now. The most useful benefit they present for this paper is their ability to use contextual information when mapping between input and output sequences.
A deep neural network for machine translation implies the use of a sequence-to-sequence model, consisting of two RNNs: an encoder that processes the input and a decoder that generates the output.
To meaningfully assess the model’s performances, texts from a translation company and thoughts from skilled experts about specialized topics will be tested.
AUTOCONFIGURATION ALGORITHM FOR A MULTIPLE INTERFACES ADHOC NETWORK RUNNING...IJCNC
Network configuration is the assignment of network parameters necessary for a device to integrate the
network, examples being: an IP address, netmask, the IP address of the gateway, etc ... In the case of
Mobile Ad hoc NETworks (MANETs), the connectivity of nodes is highly dynamic and a central
administration or configuration by the user is very difficult. This paper presents an autoconfiguration
solution for ad hoc networks running the widely implemented version of OLSR routing protocol, the 2003
RFC 3626 [1]. This solution is based on an efficient Duplicate Address Detection (DAD) algorithm,
which takes advantage of the genuine optimization of the OLSR routing protocol. The proposed
autoconfiguration algorithm is proved to operate correctly in a multiple interfaces OLSR network.
Securing Group Communication in Partially Distributed SystemsIOSR Journals
This document summarizes an approach for securing group communication in partially distributed systems. The approach divides groups into regions, each with their own Key Distribution Center (KDC). Intra-region communication uses public-key cryptography, while inter-region communication uses a hierarchical key exchange approach involving symmetric keys. Key graphs are used to represent the partial distribution structure, and rekeying strategies are employed when users join or leave groups to dynamically update keys and prevent unauthorized access. The approach aims to provide security properties like authenticity, confidentiality and integrity, while maintaining scalability for distributed systems with changing group membership.
Reggaeton originated as a blending of West Indian music like reggae and dancehall with Latin American genres like salsa and merengue as well as hip hop. While it takes influence from hip hop and Jamaican dancehall, reggaeton has developed its own distinct beat and rhythm. The genre first emerged in Panama as "Spanish reggae," an adapted version of Jamaican reggae, before spreading to Puerto Rico where rappers produced a mix of reggae and hip hop that helped spread the early reggaeton sound. Caribbean migrants working on the Panama Canal in the early 1900s influenced the development of reggaeton in Panama.
The document lists key details about the life and work of American artist Jackson Pollock including some of his major paintings from 1938 to 1953 such as "Hacia el Oeste" and "Number 32", as well as photos of him with other artists from the New York School. It also mentions Pollock's relationship with Peggy Guggenheim who supported his work and a famous quote of his about expressing feelings rather than illustrating them.
This document summarizes the conditions of poverty in America, describing a "second America" where millions live in poverty without jobs or adequate housing, trapped in a "triple ghetto" of race, poverty, and misery. It notes that while America enjoys vast material prosperity, many perishing on "a lonely island of poverty". The civil rights movement aims to address this problem of "two Americas" and make the nation indivisible with liberty and justice for all.
The document discusses three ways of applying CSS: inline, internal, and external. It provides examples of each method and explains their differences. Inline CSS is written directly in HTML tags, internal CSS is defined within the <style> tag in the <head> section, and external CSS has the styles defined in a separate .css file that is linked via the <link> tag. The document also covers various CSS properties for formatting text like font, color, size, alignment; box model properties like margin, padding, border; and CSS selectors like classes and IDs.
The document discusses layered network architecture and the ISO/OSI model. It begins with explaining that layered architecture divides network functionality across different layers, with each layer providing services to the layer above it. It then provides answers to various questions about layered architecture and the ISO/OSI model. Specifically, it summarizes the purpose and functions of different layers like the presentation layer, which performs translation, encryption, and data compression between systems. It also explains concepts like encapsulation, peer-to-peer communication, and how layered architecture enables communication between hosts.
- Data can be analog or digital, with analog being continuous and digital having discrete states. Analog signals are also continuous while digital signals have a limited set of values.
- Periodic analog signals like sine waves can be simple or composite, consisting of multiple sine waves. Nonperiodic signals are commonly used for digital data transmission.
- Digital signals represent information using discrete signal levels that can be encoded as voltages, with more levels allowing more bits to be sent per signal. The required bit rate depends on the data transmission rate and number of bits used per sample or character.
This powerpoint presentation contains quotes from Dr. Martin Luther King Jr. about topics like hope, leadership, darkness and light, freedom, human progress, power, truth and love overcoming evil, judging people by character rather than skin color, and sacrificing physical life for spiritual freedom. The presentation aims to honor Dr. King through sharing his influential words on these important subjects.
The document discusses network models including the OSI model and TCP/IP model. It describes the seven layers of the OSI model and the four layers of the TCP/IP model. For each layer, it provides details on their functions and protocols. It also compares the OSI and TCP/IP models, noting they are both based on layered architectures but that the TCP/IP model combines some layers and better fits existing protocols.
The document discusses network models including the OSI model and TCP/IP model. It describes the seven layers of the OSI model and the functions of each layer. It also discusses the four layers of the TCP/IP model and compares the two models, noting they are similar in concept but differ in number of layers and how protocols fit within each model.
The document summarizes the seven layers of the OSI reference model:
1) The physical layer is responsible for physical connections between devices and defines characteristics like data rates and topology.
2) The data link layer frames data and ensures error-free transmission between nodes through flow control and error checking.
3) The network layer handles packet routing and logical addressing between independent networks.
4) The transport layer manages reliable data transfer through segmentation, reassembly, and connection control using TCP or UDP.
This document provides an overview of network models, including the OSI and TCP/IP models. It describes the seven layers of the OSI model and the functions of each layer. The four layers of the TCP/IP model are also explained, along with their relationship to the OSI layers. Key topics covered include data encapsulation, peer-to-peer communication between layers, and the responsibilities of the physical, data link, network, transport, and application layers.
This document provides an overview of network models, including the OSI and TCP/IP models. It describes the seven layers of the OSI model and the functions of each layer. The four layers of the TCP/IP model are also explained, along with their relationship to the OSI layers. Key topics covered include data encapsulation, peer-to-peer communication between layers, and the responsibilities of the physical, data link, network, transport, and application layers.
The document summarizes the seven-layer OSI model. It describes each layer of the OSI model in detail, including the functions and responsibilities of the physical, data link, network, transport, session, presentation, and application layers. It explains that the OSI model divides network communication tasks into smaller and more manageable parts handled by different layers, with each layer building on the functions of those below it.
The document provides information about the ISO/OSI 7-layer model and TCP/IP 4-layer model for network communication. It describes the layers and functions of each model. The ISO/OSI model defines seven layers for complete communication including physical, data link, network, transport, session, presentation and application layers. The TCP/IP model has four layers - host-to-network, internet, transport and application layer. It also compares the two models highlighting differences in their approach, layers, services provided, and protocol usage.
The document discusses the 7-layer OSI model, which characterizes and standardizes communication functions across different systems to enable interoperability. It describes each of the 7 layers - physical, data link, network, transport, session, presentation, and application layer - and their respective roles and functions in managing the flow of data from one application to another. Each layer provides services to the layer above and receives services from the layer below, with layers 1-4 relating to communications technologies and layers 5-7 relating to user applications.
The document summarizes the 7 layers of the OSI model and how data is transmitted through each layer. As data flows down the layers, it is broken into smaller pieces and encapsulated with headers at each layer. At the physical layer, data takes the form of electrical signals made up of 1s and 0s that can be transmitted across physical media.
This document contains a student's assignment responses summarizing key aspects of data communication and the internet model. The student lists the layers of the internet model and describes the network support layers and user support layer. They explain peer-to-peer processes, how information passes between layers, and the purpose of headers and trailers. Responsibilities of various layers are provided, including differences between addresses. Correlations between OSI and internet layers are drawn.
The document describes the seven layers of the OSI model, which is a framework for how applications in one computer can communicate with applications in another computer over a physical medium. It provides details on the functions of each layer, including the physical, data link, network, transport, session, presentation, and application layers. Each layer has a specific role in establishing and maintaining communication between devices, with lower layers dealing with physical connectivity and higher layers focusing on software applications and services.
The document discusses the OSI model, which is a standard framework for networking. It describes the seven layers of the OSI model from physical to application layer. Each layer has a specific function and provides services to the adjacent layer. The physical layer deals with physical connections and bit-level transmission. The data link layer handles frame delivery and error control. The network layer routes packets across networks. The transport layer ensures end-to-end delivery of messages. Higher layers include the session, presentation and application layers, which establish communication sessions, handle formatting and provide user services respectively.
Osi Layer model provided by TopTechy.comVicky Kamboj
The document summarizes the Open Systems Interconnection (OSI) model, which describes how information is transferred between software applications running on different computers connected over a network. It explains that the OSI model defines 7 layers - physical, data link, network, transport, session, presentation and application layer - through which data passes as it travels from the source to destination. Each layer adds header information and communicates with its corresponding layer in the source/destination computer as well as with layers above and below it to successfully transfer information between applications across a network.
The OSI model is a 7-layer architecture for data transmission across networks developed by ISO in 1984. Each layer has a specific function and works collaboratively with the other layers. The physical layer handles physical connections and transmits raw bits. The data link layer handles framing, addressing, and error checking to transmit error-free frames between nodes. The network layer handles logical addressing and routing to transmit packets between different networks.
osi vs tcp/ip
you can get the contents from the slides of forouzan and tanenbaum of computer networking.
application layer
session layer
data link layer
presentation layer
network layer
physical layer
transmission in each osi layer
transmission in each tcp/ip layer
This document provides an overview of network models and addressing. It discusses layered network models including the OSI model and its seven layers (physical, data link, network, transport, session, presentation, application). It also discusses the TCP/IP protocol suite and how it maps to the OSI layers. The chapter covers addressing in networks including physical, logical, port, and specific addresses. Examples are provided to illustrate how addresses are used at different layers for communication between processes on different devices.
The open system Interconnection (OSI) reference.pptxwesendesta2
The document describes the OSI reference model, which defines 7 layers for network communication: physical, data link, network, transport, session, presentation, and application. Each layer performs discrete tasks to prepare data for transmission across a network, such as adding addressing, error checking, and formatting. Data moves down and then up the layers of the sending and receiving computers respectively. The layers work together to reliably transmit packets of data between applications running on different devices.
The document discusses the OSI and TCP/IP models for networking. It describes the seven layers of the OSI model - physical, data link, network, transport, session, presentation, and application layers. It also outlines the four layers of the TCP/IP model - application, transport, internet, and network interface layers. Each layer has a specific function, with the physical layer concerned with transmitting raw data and the application layer allowing direct interaction between software and users. The models provide frameworks for understanding how data moves between devices on a network.
The document discusses the Open Systems Interconnection (OSI) model, which defines seven layers of network communication. The seven layers are the physical, data link, network, transport, session, presentation, and application layers. Each layer has a specific function, with the lower layers dealing with physical connectivity and data transmission and the higher layers focusing on software applications and end-user interactions. The document provides details on the functions of each layer, such as the physical layer defining connections, signals, and topologies, the data link layer handling framing, addressing, and error control, and the transport layer providing service addressing, segmentation/reassembly, and connection control.
For an HTML/JavaScript assignment, the student must draw the DOM tree for a provided HTML program and write JavaScript code to display the node type, value, and name of all child nodes of the <form> tag. The code should be written inside a getInformation() function that is called by a button click event.
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The document discusses different mathematical proofs using induction. It provides examples of proving statements about odd numbers, divisibility by primes, equalities, properties, and inequalities using induction. The key steps are to first prove the base case, then assume the statement is true for some value n and use that to prove it is true for n+1.
This document contains an assignment on propositional logic that is due on April 5th or 6th, depending on the class. It includes 8 questions covering topics like identifying propositions, writing logical statements using operators, simplifying logical formulas, constructing formulas from truth tables, proving logical equivalences, and using resolution to prove statements.
This document outlines the requirements for a mid-term exam on internet programming. Students are asked to create an easy 6x6 sudoku puzzle generator that:
1) Randomly generates initial numbers within the constraints of the puzzle.
2) Allows the user to select and place numbers, and delete previously placed numbers following the rules of sudoku.
3) Counts the number of steps taken by the user and detects when the puzzle is solved.
Grading will consider the correctness of the program and the presentation of the web page interface.
This document provides the details of Assignment 4 which is due on April 26th or 27th depending on the class. It lists 7 questions related to concepts like transitive closure, equivalence relations, partitions, partial order relations, and Hasse diagrams. Students are asked to find transitive closures of relations, identify which relations are equivalence relations, determine if matrices represent equivalence relations, identify which subsets are partitions, determine if matrices represent partial order relations and generate Hasse diagrams, determine if a given diagram represents a partial order, and draw the Hasse diagram for a given set inclusion diagram.
This document provides details for Assignment 4 which is due on April 26th or 27th depending on the class. It includes 6 questions related to concepts like transitive closure, equivalence relations, partitions, partial order relations, and Hasse diagrams. Students are asked to find transitive closures of relations, determine which relations are equivalence relations, identify if matrices represent equivalence relations, determine which subsets are partitions, identify which matrices represent partial order relations and generate Hasse diagrams for them, determine if a given diagram represents a partial order, and draw the Hasse diagram for a given set inclusion diagram.
This document contains an assignment with 5 questions on sets, proofs using induction, contradiction, and contrapositive. The deadline for the assignment is April 26th for Thursday classes and April 27th for Friday classes. The assignment was written by Harshit Kumar on April 13, 2012.
Proof by resolution is a method of proving that a statement is logically valid or invalid. It involves assuming the negation of the statement and showing that this leads to a contradiction. A contradiction means the original statement must be true, proving the statement's validity.
The document provides instructions for designing a web page about Presidents of Korea. It includes HTML and CSS files to modify as well as images of the presidents. The assignment is to style the web page by modifying the CSS file to display the president images in a 2x2 grid, center their names below in blue text, and add spacing between the images and browser edges. It also asks to create a navigation bar HTML file and new page about President Rhee Syung-Man with 1000 words.
This document contains an assignment that is due on April 5th or 6th depending on the class. It consists of 8 questions involving logical expressions and formulas. The questions cover topics like identifying propositions, writing logical expressions using operators, simplifying formulas, constructing formulas from truth tables, proving equivalences, and using resolution to prove statements.
This document introduces some basic concepts of set theory, including:
1) Defining sets by listing elements or describing properties. Common sets include real numbers, integers, etc.
2) Basic set operations like union, intersection, difference, and complement.
3) Relationships between sets like subset, proper subset, and equality.
4) Other concepts like partitions, power sets, and Cartesian products involving ordered pairs from multiple sets.
This document outlines an assignment for Harshit Kumar due on March 23rd. It instructs him to use truth tables to prove 5 logical equivalence rules: (1) material implication, (2) biconditional, (3) distributive law, (4) DeMorgan's laws, and (5) idempotent law. For the idempotent law, three methods of proof are required as discussed in class.
This document discusses propositional logic and covers topics like propositions, common logical operators like negation and conjunction, proving the equivalence of logical formulas, constructing logical formulas based on truth tables, and simplifying logical formulas using laws like De Morgan's laws and distribution laws. Examples are provided for each topic to illustrate key concepts in propositional logic.
This document outlines the topics, grading policy, references, and contact information for a discrete mathematics course. The topics section lists key concepts like set theory, logic, induction, and graph theory. Assignments are 30% of the grade, with midterm and final exams each accounting for 25%. The remaining 20% depends on participation and attendance. Two textbooks and an online reference are provided. Contact is given as an email address for a professor in room 525 of the IT building.
This document provides an assignment on data communication concepts including CRC calculations, transmission delay, propagation delay, end-to-end delay, and queuing delay. It includes 5 questions with answers on these topics. Key concepts covered are calculating delays for different frame sizes being sent between hosts over different distances, determining the number of frames needed to transfer a large file, and calculating total end-to-end delay for a multi-hop transfer. Formulas for delays are provided to help solve the problems.
The document contains questions regarding the efficiency of stop-and-wait and sliding window protocols. It defines key terms like frame length, propagation delay, transmission delay, and efficiency. It then asks the reader to calculate efficiency for different scenarios based on these definitions, including varying frame sizes, data rates, propagation delays, and window sizes.
This document contains a collection of tweets from various users. It discusses topics like a Harry Potter animated sequence, a concert performance of Vivaldi's Gloria where an audience member had an awkward meltdown, car trouble on I-40 which required a tow truck, and an upcoming concert with the group Time For Three.
Let's Integrate MuleSoft RPA, COMPOSER, APM with AWS IDP along with Slackshyamraj55
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Taking AI to the Next Level in Manufacturing.pdfssuserfac0301
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2. Which barriers stand in the way of AI adoption.
3. How data quality and governance form the backbone of AI.
4. Organizational processes and structures that may inhibit effective AI adoption.
6. Ideas and approaches to help build your organization's AI strategy.
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Partecipate alla presentazione per immergervi in una storia di interoperabilità, standard e formati aperti, per poi discutere del ruolo importante che i contributori hanno in una comunità open source sostenibile.
BIO: Sostenitrice del software libero e dei formati standard e aperti. È stata un membro attivo dei progetti Fedora e openSUSE e ha co-fondato l'Associazione LibreItalia dove è stata coinvolta in diversi eventi, migrazioni e formazione relativi a LibreOffice. In precedenza ha lavorato a migrazioni e corsi di formazione su LibreOffice per diverse amministrazioni pubbliche e privati. Da gennaio 2020 lavora in SUSE come Software Release Engineer per Uyuni e SUSE Manager e quando non segue la sua passione per i computer e per Geeko coltiva la sua curiosità per l'astronomia (da cui deriva il suo nickname deneb_alpha).
Programming Foundation Models with DSPy - Meetup SlidesZilliz
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Have you ever been confused by the myriad of choices offered by AWS for hosting a website or an API?
Lambda, Elastic Beanstalk, Lightsail, Amplify, S3 (and more!) can each host websites + APIs. But which one should we choose?
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The original Czech 🇨🇿 version of the presentation can be found here: https://www.slideshare.net/slideshow/hlavni-novinky-souvisejici-s-ccs-tsi-2023-2023-1695/269688092 .
The videorecording (in Czech) from the presentation is available here: https://youtu.be/WzjJWm4IyPk?si=SImb06tuXGb30BEH .
For the full video of this presentation, please visit: https://www.edge-ai-vision.com/2024/06/building-and-scaling-ai-applications-with-the-nx-ai-manager-a-presentation-from-network-optix/
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HCL Notes und Domino Lizenzkostenreduzierung in der Welt von DLAUpanagenda
Webinar Recording: https://www.panagenda.com/webinars/hcl-notes-und-domino-lizenzkostenreduzierung-in-der-welt-von-dlau/
DLAU und die Lizenzen nach dem CCB- und CCX-Modell sind für viele in der HCL-Community seit letztem Jahr ein heißes Thema. Als Notes- oder Domino-Kunde haben Sie vielleicht mit unerwartet hohen Benutzerzahlen und Lizenzgebühren zu kämpfen. Sie fragen sich vielleicht, wie diese neue Art der Lizenzierung funktioniert und welchen Nutzen sie Ihnen bringt. Vor allem wollen Sie sicherlich Ihr Budget einhalten und Kosten sparen, wo immer möglich. Das verstehen wir und wir möchten Ihnen dabei helfen!
Wir erklären Ihnen, wie Sie häufige Konfigurationsprobleme lösen können, die dazu führen können, dass mehr Benutzer gezählt werden als nötig, und wie Sie überflüssige oder ungenutzte Konten identifizieren und entfernen können, um Geld zu sparen. Es gibt auch einige Ansätze, die zu unnötigen Ausgaben führen können, z. B. wenn ein Personendokument anstelle eines Mail-Ins für geteilte Mailboxen verwendet wird. Wir zeigen Ihnen solche Fälle und deren Lösungen. Und natürlich erklären wir Ihnen das neue Lizenzmodell.
Nehmen Sie an diesem Webinar teil, bei dem HCL-Ambassador Marc Thomas und Gastredner Franz Walder Ihnen diese neue Welt näherbringen. Es vermittelt Ihnen die Tools und das Know-how, um den Überblick zu bewahren. Sie werden in der Lage sein, Ihre Kosten durch eine optimierte Domino-Konfiguration zu reduzieren und auch in Zukunft gering zu halten.
Diese Themen werden behandelt
- Reduzierung der Lizenzkosten durch Auffinden und Beheben von Fehlkonfigurationen und überflüssigen Konten
- Wie funktionieren CCB- und CCX-Lizenzen wirklich?
- Verstehen des DLAU-Tools und wie man es am besten nutzt
- Tipps für häufige Problembereiche, wie z. B. Team-Postfächer, Funktions-/Testbenutzer usw.
- Praxisbeispiele und Best Practices zum sofortigen Umsetzen
Threats to mobile devices are more prevalent and increasing in scope and complexity. Users of mobile devices desire to take full advantage of the features
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HCL Notes and Domino License Cost Reduction in the World of DLAUpanagenda
Webinar Recording: https://www.panagenda.com/webinars/hcl-notes-and-domino-license-cost-reduction-in-the-world-of-dlau/
The introduction of DLAU and the CCB & CCX licensing model caused quite a stir in the HCL community. As a Notes and Domino customer, you may have faced challenges with unexpected user counts and license costs. You probably have questions on how this new licensing approach works and how to benefit from it. Most importantly, you likely have budget constraints and want to save money where possible. Don’t worry, we can help with all of this!
We’ll show you how to fix common misconfigurations that cause higher-than-expected user counts, and how to identify accounts which you can deactivate to save money. There are also frequent patterns that can cause unnecessary cost, like using a person document instead of a mail-in for shared mailboxes. We’ll provide examples and solutions for those as well. And naturally we’ll explain the new licensing model.
Join HCL Ambassador Marc Thomas in this webinar with a special guest appearance from Franz Walder. It will give you the tools and know-how to stay on top of what is going on with Domino licensing. You will be able lower your cost through an optimized configuration and keep it low going forward.
These topics will be covered
- Reducing license cost by finding and fixing misconfigurations and superfluous accounts
- How do CCB and CCX licenses really work?
- Understanding the DLAU tool and how to best utilize it
- Tips for common problem areas, like team mailboxes, functional/test users, etc
- Practical examples and best practices to implement right away
Deep Dive: AI-Powered Marketing to Get More Leads and Customers with HyperGro...
Lecture3layered archi
1. Layered Architecture or Network Architecture
The layered architecture consists of the set of layers, as explained in the class, each layer
is nothing but a collection of functions combined in one group. So, bottom line is, all the
layers make the communication process achievable, by dividing functionality among the
layers. Also each layer provides services to the layer above it. In the last lecture, there
were five points why layers are required.
Q. Why layers are required, cannot we make only one layer?
Answer: No, as explained in previous lecture.
Q. What is peer-to-peer communication?
Between machines layer ‘x’ on one machine, communicates with the layer ‘x’ on another
machine, a kind of indirect communication (by taking help of intermediate layers), except
the physical layer. Because the physical layer of one host connects with the physical layer
of another host through the medium directly. Those layers that communicate with the
corresponding layer on another machine are called as peer-to-peer layers and the
communication between peer to peer layers is called as peer-to-peer communication.
Circles with X represent routers. A and B are hosts are communicating, in this example
we are assuming that there are only two routes, whereas in practical there can be multiple
routers in between.
2. Q. What is Encapsulation?
Answer:
Layer 7 which is the topmost layer in layered architecture interacts with the application,
and the purpose of this layer is to get the message from the sender and forward to the
layer below it i.e. to layer 6 or take message from the layer below it (i.e. layer 6) and
deliver to the application. Application may be interacting with the various applications
running on the computer. Layer 7 is only concerned about interacting with the application
executing on the machine. Layer 7 and Layer 1 don’t attach any header to the message.
All the layers expect layer 7 transform the received message and attach the respective
header or trailer.
Q Why all the layers except layer 7 transform the message?
Answer: Because layer 1 only takes message from the application and forward it to the
layer 6, whereas each layer except layer 1 has some function to perform, which they do
when they receive message from the layer above it, and then attach the header also. Also,
there is no layer above layer 1, so layer 1 has nothing to do for any one else, except the
take the message from the applications in execution or delivers the message to the
application in execution.
Q What is layer to layer interface or Service Access Point?
Answer: Messages are passed from one layer to another layer through an interface; So
that means an interface exist between every pair of layers, i.e.
Layer 7-Layer 6 interface, between layer 7 and layer 6
Layer 6-Layer 5 interface, between layer 6 and layer 5, and so on.
3. The upper layers are implemented in the software and lower layers are implemented in
both software and hardware, except for the physical layer which is completely hardware.
Q How layered technology helps in achieving communication between two hosts?
Answer: As shown in above figure, with gives an over all view of layered architecture,
L7 data means the data unit at layer 7, L6 data means data unit at layer 6 and so on. The
process starts at layer 7, and then moves from layer n to layer n-1 in descending order at
sending side and ascending order at receiving side. At each layer (except layer 7 and
layer 1), a header is added and at layer 3, a header and trailer are added. When the
formatted data unit passes through the layer 1, it is changed into electromagnetic signal
and transported along a physical link.
Upon reaching the destination, the signal passes into layer 1; layer
1 transforms the received signal back into digital data. The data units then move back up
from layer n to layer n+1 through the layered architecture. As each block of data reaches
the next higher layer, the headers and trailers attached to it at the corresponding layer are
removed and actions appropriate to that layer are taken. By the time message reaches
layer 7, the message is in a form that it can be delivered to the application in execution.
ISO/OSI Model
Q What do you mean by ISO/OSI Model?
Answer: ISO is an acronym for International Standards Organization and OSI is an
acronym for Open Systems Interconnection.
Q. What is this ISO for? (You will not be asked this question in exam)
Answer: ISO is a word wide organization that takes formulates the standard and observer
that standards are being followed by everybody. This ensures compatibility and
scalability in future.
Q. What is OSI?
Answer: As told above, OSI is an acronym for Open Systems Interconnection. To
understand it, you need to break these into three words and understand each word
individually.
Open: Open means one who is ready to accept any thing and give any thing but is an
individual. For example: I am open to smoking and drinking, i.e. I don’t mind taking hard
drink and smoke.
System: System, you all know is a computer. But here systems are Open, which means
there are autonomous or individual in nature and can receive messages and send
messages.
Interconnection: Interconnection means connecting in between.
So, if we combine all three of them, what we can make out is, interconnecting
autonomous systems together.
Q. How many layers are in the ISO/OSI Model?
Answer: There are seven layers in the ISO/OSI Model.
1. Application Layer
2. Presentation Layer
3. Session Layer
4. Transport Layer
4. 5. Network Layer
6. Data Link Layer
7. Physical Layer
Application Layer
Q. What is the purpose of Application Layer?
Answer: As explained before, this is the topmost layer in ISO/OSI model, and it interacts
with the applications in execution as shown in figure below.
(i) (ii)
In figure (i), Application layer takes message from the user (here user is like some
application, for example chat application or telnet application or ftp application) and
gives that message to the layer below it i.e. presentation layer (for other functions to be
performed on this message) through an interface present between application layer and
presentation layer called as service access point. Note that no header is attached to the
message at this layer.
In figure (ii), Application layer takes messages from the layer below it i.e. presentation
layer, here also messages pass between presentation layer to the application layer through
an interface called as service access point, and deliver it to the appropriate application in
execution for which that message is meant for.
Q. What is the purpose of Presentation Layer?
Answer: Presentation layer is concerned about the language between used between two
hosts or between two systems, Since two systems are open as explained below, they are
autonomous or individual in nature, so each one of them can have their own language or
character set. Thus one of the jobs that Presentation Layer does is Translation.
Actually there are three functions that Presentation layer does:
1. Translation
2. Encryption
3. Data Compression
Q What is Translation, and why is it required?
Answer: The process in two hosts or two systems are usually exchanging information in
the form character strings, numbers etc. The information is changed to bit, this
conversion of character strings and numbers into bits can be done in two ways, one way
is ASCII and second way is EBCDIC. So let us assume that Host A uses ASCII
representation of converting his message (remember message is combination of strings
5. and numbers) and Host B uses EBCDIC. If any message in ASCII is sent to Host B, he
will not be able to understand that. The solution to this is, presentation layer at the sender
converts ASCII message to some common format which when received by Host B is
converted into EBCDIC. What that common format is? That is another question, we wont
get into that.
Q What is Encryption? Why is it required?
Answer: Encryption is encoding, i.e. converting message from intelligible form to
unintelligible form. This is done to ensure security, so that while some confidential
message is in transit and some other third person manages to gain access to that message,
he should not be able to know what it means, if the message is not encrypted before
transmission, he can make out the meaning of it. Presentation layer at the sender end
encrypts the message and the encrypted message is transmitted over the medium. After
traveling through the medium, encrypted message reaches the physical layer of the
destination, where encrypted message is again decrypted to get the original message. So,
decryption is done at receive end, and is opposite of encryption. We can define
decryption as, converting message from unintelligible form to intelligible form, so that
one can make out what it mean.
Q. What is Data Compression? Why is it required?
Answer: Data Compression reduces the number of bits contained in the information. To
understand why data compression is done or what the advantages of doing data
compression are, let us take one example.
Suppose host A wants to transmit to Host B. They both are on point-to-point link (i.e.
Host A is on one side of the link and Host B is on the other side of the link, and link is
not shared by anyone else). The link can carry 10 bits/sec that means Host A can place 10
bits on the link in 1 sec. If Host A has a packet of size 20 bits, how much time will it take
to transmit it? Obviously the answer is 2 seconds. If presentation layer of A can compress
that message to half, i.e. after compression the size of the packet is 10 bits, now how
much time will it take? This time the answer is 1 sec, which is less than time taken to
send the same uncompressed packet. So transmission time is reduced by compression.
So, Presentation layer at the source compresses the message and compressed message is
given to the next layer down and finally reaches the physical layer of the source, which
transmits the message on the medium, medium travels through the medium and is
received by the receiver’s physical layer. Physical layer of the receivers gives the
message to the layer in upward direction. Finally message reaches the presentation layer
where message is decompressed to retrieve the original message. (Remember that when a
message travels down the layer, a header is attached to the message at every layer except
the Application layer and physical layer, and in data link layer a trailer is also attached.
Also when a message travels up the layer, headers are removed at every layer except the
application layer and physical layer)
So after message is translated, encrypted and compressed at the presentation layer, it is
passed to the lower layer i.e. Session layer, through interface present between the
presentation and session layer. Figure below depicts the behavior of presentation layer.
6. Session layer
Q. What is the purpose of Session Layer?
Answer: Session layer enable for processes in two different systems to enter into a dialog.
It allows communication between two processes to take place either in half-duplex or
full-duplex. So Session layer does dialog control.
Session layer allows a process to add checkpoints (also called as synchronization points)
into a stream of data. For example, if a system is sending a file of 2000 pages, it is
advisable to add checkpoints after every 100 pages. Checkpoint helps in acknowledging
that after every 100 page is received, an acknowledge goes to the sender. In this case, if a
crash happens during the transmission of page 523, the only pages that need to be resent
after system recovery are pages 501 to 600, and onwards.
Transport Layer
Q. What is the purpose of Transport Layer
Answer: The transport layer is responsible for source to destination delivery of the entire
message. What I mean by that, transport layer is not concerned how data travel from
source to destination, the only concern of transport layer is that it should reach there with
out any error and without any loss. In must simpler words, transport layer ensures that
data reaches at the destination intact overseeing error control and flow control. The
concern about how data travel is of the lower layer to transport layer, i.e. network layer.
As a matter of fact, lower three layers are concerned about how to route the packet from
source to destination i.e. network layer, data link layer and physical layer. The
responsibilities of transport layer are:
1. Service Point Addressing
2. Segmentation and Reassembly
3. Connection Control
4. Flow Control
5. Error Control
7. Network Layer
Q. What is the purpose of Network Layer?
Answer: The network layer is responsible for source to destination delivery of a packet
possibly across multiple networks; again network layer relies on the layer below it for
actual transmission. The layer below network layer is data link layer. But yes data link
layer define the route that the packet will follow or packet can also take dynamic route
defined by the intermediate routers on the run. But for sending a packet from one router
to another, there is a medium in between, to travel through the medium and data link
layer and physical layer comes into picture, so network layer without the help of data link
layer and physical layer is incomplete. Similarly transport layer relies on network layer,
and transport layer is incomplete without the network layer and layers below network
layer.
The responsibilities of network layer are
1. Routing
2. Logical Addressing
Data Link Layer
Q What is the purpose of Data Link Layer?
Answer: The data link layer is responsible for end to end delivery of frames i.e. it is the
data link layer which actually do the job of sending frame from one end of link to other
end of the link (in a point to point link) obviously the actual transmission of frame is
done by the physical layer i.e. putting the bits of the frame on the link. Data link layer has
to take care of flow control, error control between two links that falls in the whole path
from source to destination. The responsibilities of data link layer are
1. Framing
2. Physical Addressing
3. Flow Control
4. Error Control
5. Access Control
Physical Layer
Q. What is the purpose of Physical Layer?
Answer: Physical layer is the lower layer, and converts the message into bits; put the bits
on to the medium. The number of bits that the physical layer can put on the medium or
transmit through the medium is called as the transmission rate. Below is the figure the
depicts the transformation done to the message at physical layer.
8. The physical layer is concerned with the following
1. Physical characteristics of the interfaces and medium
2. Representation of bits
3. Data Rate or Transmission Rate
4. Link Configuration
5. Physical topology
Summary of ISO/OSI Model