The Network Layer, also known as Layer 3, is responsible for routing data between nodes in a network. This layer provides logical addressing, routing, and congestion control, enabling data to be transmitted between devices on different networks. Key protocols used in this layer include:

1. IP (Internet Protocol)

2. ICMP (Internet Control Message Protocol)

3. IGMP (Internet Group Management Protocol)

4. OSPF (Open Shortest Path First)

5. EIGRP (Enhanced Interior Gateway Routing Protocol)

The Network Layer performs the following functions:

1. Routing: Determines the best path for data to travel between nodes.

2. Logical addressing: Assigns IP addresses to devices for identification.

3. Congestion control: Manages network traffic to prevent overload.

4. Fragmentation and reassembly: Breaks down and reassembles data packets.

In the context of blockchain, the Network Layer is responsible for routing transactions and blocks between nodes in the network, enabling the decentralized and distributed nature of blockchain technology. This layer plays a critical role in ensuring that data is transmitted efficiently and securely, and that the network remains connected and resilient.