Which layer of the TCP/IP model includes the Internet Protocol (IP)?

The TCP/IP model is a conceptual framework that standardizes network communication functions. The Network layer, also known as the Internet layer, is responsible for logical addressing, packet forwarding, and routing across different networks. The Internet Protocol (IP) is the principal communications protocol in this layer. It defines the format of packets, called datagrams, and the addressing system (IP addresses) used to deliver them from a source host to a destination host based on their addresses. All other layers rely on the Network layer's IP protocol for this fundamental packet delivery service.

A. The Physical or network access layer handles the physical transmission of data over the network medium and hardware addressing (e.g., MAC addresses), not logical IP addressing.

B. The Application layer provides network services directly to end-user applications, using protocols like HTTP, FTP, and SMTP.

D. The Transport layer is responsible for host-to-host communication, segmentation, and error control, using protocols like TCP and UDP, which in turn use IP for delivery.

1. Internet Engineering Task Force (IETF) RFC 1122: Braden

R. (Ed.). (1989). Requirements for Internet Hosts -- Communication Layers. RFC 1122. Section 1.3.2

"The TCP/IP Reference Model

" explicitly states

"Below the transport layer is the internetwork layer... The internetwork layer in the TCP/IP protocol suite is the IP layer. Its function is to route datagrams to their destination."

2. Kurose

J. F.

& Ross

K. W. (2021). Computer Networking: A Top-Down Approach (8th ed.). Pearson. In Chapter 1

Section 1.5.2

"The Internet Protocol Stack

" the authors describe the Network Layer: "The Internet’s network layer is responsible for moving network-layer packets known as datagrams from one host to another. The Internet network layer includes the celebrated IP Protocol..."

3. MIT OpenCourseWare

6.033 Computer System Engineering

Spring 2018. In the course textbook

Saltzer

J. H.

& Kaashoek

M. F. (2009)

Principles of Computer System Design: An Introduction

Chapter 6

"Networking

" Section 6.1.2

"The Internet Protocol stack

" describes the Network layer as the layer that "routes packets from their source to their destination" and identifies IP as the primary protocol for this function.