Layers of OSI and TCP/IPOSI Assessment Answers

Table of Contents

Assignment 1 

Layers of OSI and TCP/IP 

Correlation of OSI layer with TCP/IP layer 

Network support and user support layer of TCP/IP 

Data encapsulation 

Data link layer

Difference between network and transport layer delivery 

Need of another mechanism in 

Network layer 

Transport layer 

Port, logical and physical address 

Services of application layer

Advantages of combination in OSI 

Advantage of hierarchical name 

Primary and secondary 

Need for POP3 and 

FTP

Anonymous FTP

Relation of HTTP to WWW 

URL and components

Proxy server 

SNMP components 

SNMP v1 and v2 

Similar Frame Relay network 

SVC comparison with PVC 

Identification of ATM virtual connection

SONET

Assignment 2 

UDP and Reliability 

Unreliability of UDP and IP 

The uniqueness of the port address 

Network and transport layer 

IP address, port address and the socket address 

Connection-oriented and connectionless service 

Reliable and unreliable service

3 stage of connection oriented 

3 way handshake 

Flow control 

Distinguishing flow control 

Error control TCP

Distinguishing error control 

Congestion control

3 phase of TCP congestion 

Reference List 

Assignment 1Layers of OSI and TCP/IPOSI

Layer 7 (Application layer)

Layer 6 (Presentation layer)

Layer 5 (Session layer)

Layer 4 (Transport layer)

Layer 3 (Network layer)

Layer 2 (data-link layer)

Layer 1 (physical layer)

TCP/IP

Layer 4 (Application layer)

Layer 3 (Transport layer)

Layer 2 (Internet layer)

Layer 1 (Network access layer)

Correlation of OSI layer with TCP/IP layer

The application layer in TCP/IP protocol is similar to the functioning of three layers of OSI that are (Application, Presentation and Session layer). This layer of TCP/IP replicates the working principle of OSI by providing a designated path for application to operate. However, transport layer does the job of layer 4 in OSI. Mejas et al. (2017) stated that internet layer provides relevant network packets for operator similar to network layer and network access layer does the job of data link and physical layer of OSI.

Network support and user support layer of TCP/IPThe layers of TCP/IP protocol suite that are labelled as layer 2 and 1 (Internet layer and network access) are network supported layer where as layer 4 and 3 (application and transport) are user support layers as they are responsible for presentation and application.

Data encapsulationData encapsulation is particularly being utilized for sending data by putting a separate header and sometimes trailer as well. It allows OSI layers to acknowledge data is being received and needs to be processed for further layer. In case of TCP/IP encapsulation of data attaches a header over packets that need to be sent to successive layer of protocol suite. Data encapsulation is also considered as object oriented programming concept, which can bind together the data as well as functions that helps to manipulate the data along with keeps safe from outside interface and misuse. In addition, data encapsualtion can lead to the significant OOP concept of data mining.

The wrapping of private data in the classes of object oriented programming is encapsulated. Data encapsulation is one of the mechanims to bundle the data as well as the functions that utilise them as well as data abstraction is conaidered as a mechanism to expose the interfaces as well as hiding the details of implementation from the user.

Data link layerThe primary responsibility of data link layer is to eliminate error while maintaining the flow of network packets to physical layer. It also handles the hardware protocols and controls media access of the network operation.

The data link layer is included in the protocol layer in a program that can handle the moving of data into as well as out of physical link in the network. The data layer is the protocol layer that transfers data between adjacent network nodes in a wide area network or between the nodes on the same local area network segment..

Difference between network and transport layer deliveryThe primary difference is that network layer delivers the packets across the connection. However, transport layer is responsible for maintaining the delivery of packets across the multiple connections of network (Zheng, 2017).

Need of another mechanism in TCP/IPSinha et al. (2017) stated that need to utilize another mechanism is to check the bit flip that occurs between the router links. It ensures that every error is reduced by monitoring the nodes which gets undetected by data link layer.

Network layerThe primary responsibility of network layer is to maintain the routing of packets that is being delivered across multiple. The layer has makes logical sense to the operator by turning the logical IP address into MAC (physical address) which is understandable by the operator. The network layer is considered as the third level of open systems interconnection model that gives data routing paths for network commnunication. Data is generally transferred in the packet forms through logical network paths in a proper ordered format. It is also controlled by the network layer. Seeting up logical connection, data forwarding, routing as well as delivering error reporting are comsidered as primary responsibilities of network layer.

Transport layerThe need to process network through end to end system connection is being provided by transport layer. This layer utilizes the end to end platform for delivering the packets to host connection.The transport layer is considered as the layer in the open system interconnection model that is responsible for end to end communication over the network. It also provides logical communication between the application procedure that is running on distinctive hosts within a layered architecture of the protocols as well as different components of the network.

The transportation layer is the layer included in the open system interconnection model that is responsible for end to end communication over the network. It also provides logical communications between the application procedures running on multiple hosts within a layered architecture of protocols.

Port, logical and physical addressPort address Logical address Physical address

The number which is assigned to port for running an application It is the IP address of any network system and used to identify particular source and distinction for the network It is also known as MAC which is a local address and used to identify LAN or WAN connection in a network

Services of application layerSome of the crucial services that are assisted by application layer are transfer of file, accessing the database and also provide mailing services for operators.

Advantages of combination in OSIThe need to send and receive packets at faster rate can be resolved by combining session, presentation and application layer of OSI. It can also help in reducing the error in codes as it reduces the repetition of codes required for session and presentation layer.

Advantage of hierarchical nameThe primary advantage of having a hierarchical name space over flat space is to have a faster processing system for search option. It also enables binary searches rather than sequential search for flat name space.

Primary and secondary DNSPrimary DNS Secondary DNS

It is responsible for handling the data that is being related to domain and also facilitates communication with secondary server DNS

It administers the redundancy of data required for processing They are responsible for receiving data zone from primary DNS

The secured nature of secondary DNS is provided through redundancy check

Need for POP3 and IMAPPOP3 (Post Office Protocol 3) is needed to facilitate the downloading of mails from inbox to local computers. However, IMAP is needed because it helps in faster processing of mails through Internet Message Access Protocol.

FTPFTP (File Transfer Protocol) has the purpose to transfer file between two computer networks and also has the ability to access software archives

Anonymous FTPIt provides an anonymous approach to user for access the files without identifying themselves in the network. It helps in downloading the files from internet without having any authenticated passwords.

Relation of HTTP to WWWHTTP or (Hyper Text Transfer Protocol) is utilized by World Wide Web (WWW) to transfer particular information over internet. It does not only publish but also allows viewers to receive HTML texts or WebPages.

URL and componentsA URL is a uniformly authenticated address that helps network operator to locate the computer location of particular network. Some of the components of URL are protocol, domain, pathway, hash and query strings.

Proxy serverSohan et al. (2015) clarified that proxy server allows an operator to access the replica of a web page in order to download or view files. Proxy server checks the authenticity of HTTP client and is further processed to designated server.

HTMLHTML (Hyper Text Mark-up Language) helps in creating a layout for web pages and application that are accessible through internet. Some of the components of HTML are DOCTYPE, header, attributes, frames and comments.

SNMP componentsSingle Network Management Protocol is particularly utilized to not only manage but also monitor the functions of network devices. Some of the components of SNMP are network devices, agents to run software and NMS that runs on the software.

SNMP v1 and v2Message types of SNMP v1 and v2 are Get request 0, Get Next Request1, Get response 2, Set request 3 and Trap4

Get request is required to request data through SNMP messages

Get Next request helps SNMP manager to send message type to discover the kind of information that can be gained from devices

Get Response is a response that message is delivered or requested

Set request allows the manager to change the parameters of messages

Trap are considered in cases when messages suffers any error

Similar Frame Relay networkA similar frame relay network cannot be connected to DLCI because these are particularly structured for a sole interface. A particular switch is assigned to DLCI connection to recognise and transfer network to designated Frame.

SVC comparison with PVCSVC PVC

These are switched virtual circuit which means it can re-establish a network connection even after the data is being sent These are permanent virtual circuit that is permanently available for manual sophistication and has separate cicuit values

Identification of ATM virtual connectionSince ATM are connected through virtual circuits, they can only be identified through virtual identifier. Therefore, two main identifiers that are Virtual path and virtual circuit identifier utilized to identify ATM connections.

SONETThe primary reason for determining a SONET as synchronous network is because it utilizes only single clock for transmission and handling the network equipments. Synchronous optical networking devices is considered as one of the stamdard digital communication protocols, used for transmitting a large volume of data over long distances utilising a fiber optice medium. With SONET, multiple digital data streams are transferred at the same time over the optical fipe utilising LEDs as well as laser beams.

Assignment 2

UDP and Reliability

Reliability is not considered important for applications as they have their own flow control and error control mechanism (Hei et al. 2017). UDP can be good transport protocol for cases where a message needs to be sent by operator without caring about reliability. Small messages can be easily sent as UDP requires very less interaction time between receiver and sender.

Unreliability of UDP and IP

The unreliability of UDP and IP does not lie on the same degree because the unreliable nature of IP surfaces in upper layer of TCP/IP protocol suite. It has been highlighted by Masirap et al. (2016) that UDP have more reliability in them rather than IP. It is due to the fact that checksum in UDP is applied to overall packet of network.

Uniqueness of port address

Port addresses do not need to be unique because port address combines with IP address to identify the server program of the network host. They are considered to be shorter than IP address because of the smaller size of domain in port address compared to the domain of IP address.

Network and transport layerNetwork layer Transport layer

It provides connection to the system and also responsible for delivering the network packets from source to network destination

It helps in the transformation of network address into MAC or physical address They are particularly connection less services that makes sure all the deliverable messages are being received from source to destination

It helps in delivering the messages in the form of packets so that nothing is left out while delivering the messages

IP address, port address and socket addressIP address Port address Socket address

This address is considered to be the system address labelled over each devices These type of address are considered to be the designated number for application to run This is generally referred as the combination of port and IP addresses and defines the boundary of server process

Connection oriented and connection less serviceConnection oriented connection less service

A virtual connection is created much before the delivery of packets

An authentication from node of destination is required for transfer of data The packets are sent without creating any connection

It transfers without any authentication

Reliable and unreliable serviceIt is considered that a reliable communication services proves to be producing positive result. On the contrary, unreliable services do not provide authenticate results and mostly scored wrong.

3 stage of connection oriented

The three stages of connection oriented are establishment of connection, transferring of relevant data and termination of connection with appropriate functionality.

3 way handshake

The three way handshake in TCP is particularly being garnered through SYN, SYN-ACK and ACK. The SYN stands for synchronized data packet and ACK for acknowledgement. The first way is when client sends a synchronized data to a designated IP. Second way handshake is when data is confirmed by the IP and the third handshake is when the IP sends an acknowledgement signal

Flow control

The management of data transfer rate between two computer nodes is flow control

Distinguishing flow controlThe flow control in data link layer manages delivery of messages in local connection where as in transport layer flow control delivers messages in global context. In data link the connection is physical where as in transport layer the connection is logical

Error control TCPTCP provides error control through check sum, acknowledgment and retransmission of messages. Liu et al. (2016) stated that check sum is done by conducting whole packet check by TCP. Acknowledgement is confirmed message by TCP to admit the delivery of packets in bits. However, eroded data are called for retransmission in case there is a missing segment or out of order segment.

Distinguishing error control

The transport layer checks for error through maintaining a sequential order of segment. It also ensure whether the data being received or not. However, data link layer encapsulates data packets into separate frames so that errors through bit correction can be initiated.

Congestion control

Congestion particularly occurs when the designated messages are stuck in network traffic which also seems to slow down the response time from network connection. Congestion control is done through open loop and closed loop congestion control. These two control methods are being managed by TCP because it requires choke packet and implicit signals that is only provided by TCP protocols.

3 phase of TCP congestion

The three TCP congestion control policies are slow start phase, avoidance phase and detection phase

Slow start phase

In this phase, after the acknowledged receipt the congestion window is being increased

Congestion avoidance

In this phase, sender intentionally increases window size to avoid congestion

Congestion detection

In this phase, the loss of required acknowledgement time leads to the detection of congestion in network

Reference

ListHei, X., Chen, J., Lu, H., Xie, G. and Meng, H., (2017, May). A UDP-based way to improve data transmission reliability. In2017 29th Chinese Control And Decision Conference (CCDC)(pp. 2612-2617). IEEE.

Liu, X., Ren, F., Shu, R., Zhang, T., Dai, T., Sha, K., Striegel, A. and Song, M., (2016). Mitigating bufferbloat with receiver-based TCP flow control mechanism in cellular networks. InAdvances in Computer Communications and Networks From Green, Mobile, Pervasive Networking to Big Data Computing(p. 65). River Publishers.

Masirap, M., Amaran, M.H., Yussoff, Y.M., Ab Rahman, R. and Hashim, H., (2016, May). Evaluation of reliable UDP-based transport protocols for Internet of Things (IoT). In2016 IEEE Symposium on Computer Applications amp Industrial Electronics (ISCAIE)(pp. 200-205). IEEE.

Mejas, A., Herrera, R., Mrquez, M., Caldern, A., Gonzlez, I. and Andjar, J., (2017). Easy handling of sensors and actuators over TCP/IP Networks by Open Source Hardware/Software.Sensors,17(1), p.94.

Sinha, P., Jha, V.K., Rai, A.K. and Bhushan, B., (2017, July). Security vulnerabilities, attacks and countermeasures in wireless sensor networks at various layers of OSI reference model A survey. In2017 International Conference on Signal Processing and Communication (ICSPC)(pp. 288-293). IEEE.

Sohan, S.M., Anslow, C. and Maurer, F., (2015, November). Spyrest Automated restful API documentation using an HTTP proxy server (N). In2015 30th IEEE/ACM International Conference on Automated Software Engineering (ASE)(pp. 271-276). IEEE.

Zheng, K., (2017). Enabling protocol routing revisiting transport layer protocol design in internet communications.IEEE Internet Computing,21(6), pp.52-57.

You Might Also Like :

Online Assignment Help

SIT202 Computer Networks TCP/IP Protocol Assessment Answer

Looking For Complete Assignment Sample Get It On WhatsApp