Which layer of the OSI model is responsible for routing packets between different networks?

Layer 3 of the OSI model, also known as the Network layer, is responsible for routing packets between different networks. This layer determines the best path for data to travel from the source to the destination, often using protocols like Internet Protocol (IP). It handles logical addressing, which allows devices on different networks to communicate by assigning unique IP addresses.

In this layer, routers operate to receive packets from one network and forward them to another, ensuring that data is directed through various intermediary networks efficiently. The use of routing tables and protocols at this layer facilitates the decision-making process regarding how to route the packets, taking into account factors like traffic load and network topology.

In contrast, Layer 2 focuses on data link functions and deals with physical addressing (such as MAC addresses) and ensures reliable transmission between devices within the same network. Layer 4, the Transport layer, is primarily concerned with end-to-end communication and ensures complete data transfer through segmentation and flow control. Layer 5, also known as the Session layer, manages sessions and dialogue between applications, focusing on maintaining connections rather than routing data between networks.