In OSI model network layer is responsible for _______.
Routing
Understanding the OSI Model Network Layer
The Open Systems Interconnection (OSI) model is a standard framework that describes how different communication systems can communicate with each other. It organizes the functions of a network into seven distinct layers. Each layer is responsible for specific tasks to ensure data is successfully transmitted from a source to a destination.
The question asks about the main responsibility of the Network Layer within this model.
Role and Responsibility of the Network Layer
The Network Layer is the third layer from the bottom in the OSI model. Its primary function is to enable data to be transferred between different networks. This involves moving variable-length data sequences (often called datagrams or packets) from a source host on one network to a destination host on a potentially different network.
The key responsibility that facilitates this internetwork communication is routing. The Network Layer determines the best path for data packets to travel across potentially multiple interconnected networks to reach their final destination. Devices like routers operate at this layer to perform the routing function.
Main tasks handled by the Network Layer include:
- Logical addressing (e.g., using IP addresses)
- Routing data packets from source to destination
- Handling network congestion
- Packet forwarding
Analyzing the Given Options
Let's look at the functions associated with each of the provided options and identify which OSI layer they belong to:
- Token management: This is a service provided by the Session Layer (Layer 5). It helps manage data exchange in some network architectures, controlling which party is allowed to transmit data at any given time.
- Dialog control: Also a function of the Session Layer (Layer 5). It manages the sessions between two communicating applications, controlling whether communication is simplex, half-duplex, or full-duplex, and managing the flow of data units.
- Physical transmission: This is the fundamental task of the Physical Layer (Layer 1). It deals with the actual transmission of raw data bits over the physical medium (like copper wires, fiber optic cables, or airwaves), defining voltage levels, physical connectors, etc.
- Routing: As explained, routing is the core responsibility of the Network Layer (Layer 3). It involves finding the best path for data packets to travel across different networks from source to destination.
Therefore, the responsibility of the Network Layer in the OSI model is routing.
Revision Table: OSI Model Layers and Functions
| OSI Layer | Name | Primary Responsibility |
|---|---|---|
| 7 | Application Layer | Provides network services directly to end-user applications. |
| 6 | Presentation Layer | Data translation, encryption, compression, formatting. |
| 5 | Session Layer | Establishes, manages, and terminates communication sessions (dialog control, token management). |
| 4 | Transport Layer | End-to-end message delivery, segmentation, flow control, error control. |
| 3 | Network Layer | Routing data packets between networks, logical addressing, path determination. |
| 2 | Data Link Layer | Node-to-node data transfer, physical addressing (MAC addresses), error detection/correction within a segment. |
| 1 | Physical Layer | Physical transmission of raw bit stream over a physical medium, defining hardware specs. |
Additional Information: The Importance of Routing
Routing is essential for the functioning of the internet and other large networks. Without routing, data packets would not know how to travel from a device on one local network to a device on a distant network.
Routers use complex algorithms and routing protocols to build and maintain routing tables, which are like maps showing the paths to different network destinations. When a packet arrives at a router, the router examines the packet's destination address and consults its routing table to decide which outgoing interface the packet should be sent through to get closer to its destination.
Effective routing ensures that data delivery is efficient and reliable, even when parts of the network are down or congested.
Important Questions from Network Layer
Firewall is a device that filters access to the protected network from the outside network. Firewalls can filter the packets on the basis of
(A) Source IP Address
(B) Destination IP Address
(C) TCP Source Port
(D) UDP Source Port
(E) TCP Destination Port
Choose the correct answer from the options given below:
The full form of ICANN is
What is the name of the protocol that allows a client to send a broadcast message with its MAC address and receive an IP address in reply?
You need 500 subnets, each with about 100 usable host addresses per subnet. What network mass will you assign using a class B network address?
Which of the following delays are present in packet switching?
