Which of the following OSI layers provides routing and related services?

The Network Layer, Layer 3 of the Open Systems Interconnection (OSI) model, is primarily responsible for packet forwarding between different networks. Its key functions include logical addressing (e.g., using IP addresses) and path determination, which is the process of selecting the best path for data to travel from source to destination. This core function is known as routing. Routers operate at this layer to make decisions on where to forward packets based on their destination network addresses.

B. Presentation Layer: This layer is responsible for data translation, formatting, encryption, and compression, ensuring data is in a usable format for the application layer, not routing.

C. Session Layer: This layer establishes, manages, and terminates communication sessions between applications. It does not handle the routing of data packets across networks.

D. Physical Layer: This layer is responsible for the transmission and reception of unstructured raw bit streams over a physical medium; it has no concept of addressing or routing.

1. International Organization for Standardization (ISO). (1994). ISO/IEC 7498-1:1994 Information technology — Open Systems Interconnection — Basic Reference Model: The Basic Model. Section 7.5.1

"Purpose

" states

"The Network-Layer provides the functional and procedural means for transmission of variable-length data-sequences from a source to a destination... through one or more networks." Section 7.5.4.2

"Routing

" explicitly lists routing as a function of this layer.

2. Kurose

J. F.

& Ross

K. W. (2017). Computer Networking: A Top-Down Approach (7th ed.). Pearson. In Chapter 4

"The Network Layer: Data Plane

" the text states

"The role of the network layer is thus to move packets from a sending host to a receiving host... The two most important network-layer functions... are forwarding and routing." (p. 304).

3. Stallings

W. (2014). Data and Computer Communications (10th ed.). Pearson. In Chapter 2

"Protocol Architecture

TCP/IP

and Internet-Based Applications

" the OSI model is detailed. Section 2.2 describes the Network Layer: "The network layer is concerned with routing data from a source to a destination through a series of intermediate nodes." (p. 41).

4. Tanenbaum

A. S.

& Wetherall

D. J. (2011). Computer Networks (5th ed.). Prentice Hall. Chapter 5

"The Network Layer

" begins by stating

"The network layer is concerned with getting packets from the source all the way to the destination... The main function of the network layer is routing packets from the source machine to the destination machine." (p. 385).