Map The Layers Of The TCP/IP Model

Map The Layers Of The Tcpip Model To T

Answer the following questions: Map the layers of the TCP/IP model to the OSI model. Each layer of OSI has a body/group that is responsible for the standards; please name them. Describe the progression through the OSI model of the following: a web browser request and connection to, and an email being sent from Outlook on a Windows machine from your APUS email account to [email protected]. Submit these assignments as a single Word document.

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Map The Layers Of The Tcpip Model To T

The Transmission Control Protocol/Internet Protocol (TCP/IP) model serves as the foundational framework for modern networking, underpinning how data is transmitted across the internet and private networks. This model comprises four layers: the Link Layer, the Internet Layer, the Transport Layer, and the Application Layer. To understand its relationship with the Open Systems Interconnection (OSI) model, which describes seven layers, it is essential to map each TCP/IP layer to its corresponding OSI layer. Additionally, each OSI layer is governed by a body or group responsible for standards, such as the International Organization for Standardization (ISO) and other standardization entities.

Mapping TCP/IP Layers to the OSI Model

The TCP/IP model can be mapped to the OSI model as follows: the TCP/IP Link Layer corresponds to the OSI Data Link (Layer 2) and Physical Layers (Layer 1). The TCP/IP Internet Layer aligns with the OSI Network Layer (Layer 3). The TCP/IP Transport Layer is equivalent to the OSI Transport Layer (Layer 4). Finally, the TCP/IP Application Layer encompasses the top three OSI layers: the Session (Layer 5), Presentation (Layer 6), and Application (Layer 7), though the TCP/IP model consolidates these functionalities into a single layer.

Responsible Bodies for OSI Layers

• Physical Layer (Layer 1): International Telecommunication Union (ITU)
• Data Link Layer (Layer 2): IEEE (Institute of Electrical and Electronics Engineers)
• Network Layer (Layer 3): International Organization for Standardization (ISO)
• Transport Layer (Layer 4): Internet Engineering Task Force (IETF)
• Session, Presentation, and Application Layers (Layers 5-7): IETF and ISO (for standards within specific areas)

Progression of Network Activities Through the OSI Model

A. Web Browser Request and Connection

When a user types a URL into a web browser and initiates a request to access a website, the data flows through each OSI layer in a systematic manner. Initially, at the Application Layer, the browser generates an HTTP request, which specifies the desired resource. This request is then passed down to the Presentation Layer, where data encryption and formatting, such as HTML, are managed, although in many cases, presentation functions are integrated within the application layer in TCP/IP. The Session Layer manages sessions and connection states, ensuring the continuity of the communication. Below this, the Transport Layer, typically using TCP, segments the data and adds header information such as port numbers. Moving to the Network Layer, IP routing determines the path, encapsulating data into packets with source and destination IP addresses. The Data Link Layer then frames these packets into frames suitable for the physical medium, attaching MAC addresses. Finally, the Physical Layer transmits raw bits over the physical connection to the server hosting the website.

In this process, when the server receives the request, the data ascends through the OSI layers in reverse order: from physical reception up to the application layer, where the server's web server software processes the HTTP request and sends back the requested web page, following the same layered process in the response path.

B. Sending an Email from Outlook

The email transmission process from Outlook on a Windows machine begins at the Application Layer, where the user composes an email message. Outlook utilizes protocols like SMTP (Simple Mail Transfer Protocol) to send emails, which integrate into the application layer’s functionality. This message is passed downward through the Presentation and Session Layers, which manage data formatting and session states, respectively. At the Transport Layer, TCP segments the email data, adding source and destination port numbers pertinent to SMTP operations. The Internet Layer adds IP addresses to route the email across the internet network to the recipient's mail server. The Data Link Layer frames the data into Ethernet frames, utilizing MAC addresses for local delivery over the network. Physical Layer then transmits the bits through the network medium to the mail server.

On the receiving end, the recipient’s mail server processes the incoming data, stripping away framing and routing the message to the recipient's inbox. When the recipient checks Outlook, the email is retrieved using protocols such as IMAP or POP3, and the process reverses, ascending through the OSI layers for display and reading.

Throughout this process, each layer's role is critical in ensuring data integrity, proper routing, and successful communication, demonstrating the OSI model's layered approach as an effective framework for understanding complex network interactions.

Conclusion

Understanding the mapping between the TCP/IP and OSI models and the progression of data through OSI layers during typical activities like web browsing and email transmission provides essential insight into network operations. Recognizing the responsible standards bodies for each OSI layer highlights the collaborative effort in establishing global networking standards. The layered approach exemplifies the modularity and interoperability essential for the functioning of complex network systems, underpinning modern digital communication.

References

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• Tanenbaum, A. S., & Wetherall, D. J. (2011). Computer Networks (5th ed.). Pearson.
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• Kurose, J. F., & Ross, K. W. (2017). Computer Networking: A Top-Down Approach (7th ed.). Pearson.
• ISO/IEC 7498-1:1994, Information technology — Open Systems Interconnection — Basic Reference Model.
• IEEE Standards Association. (2020). IEEE 802.3 Ethernet Standard.
• IETF. (2023). RFC 793: Transmission Control Protocol.
• ITU. (2012). Recommendation ITU-T X.25: Interface between Data Terminal Equipment and Data Circuit-terminating Equipment Associated with Packet Switched Networks.
• Peterson, L., & Davie, B. (2011). Computer Networks: A Systems Approach (5th ed.). Morgan Kaufmann.
• Huc, J. (2018). Networking Fundamentals: Networking Basics, Network Protocols, and Network Security. Sybex.