The Data Link Layer, also known as Layer 2, is responsible for ensuring error-free transfer of data frames between nodes on the same network. This layer provides:

1. Framing: Divides data into frames for transmission.

2. Error detection and correction: Ensures data integrity using checksums and acknowledgments.

3. Flow control: Regulates data flow to prevent congestion.

4. Medium access control: Manages access to the physical medium (e.g., Ethernet or Wi-Fi).

Protocols used in this layer include:

1. Ethernet (IEEE 802.3)

2. Wi-Fi (IEEE 802.11)

3. Point-to-Point Protocol (PPP)

4. Frame Relay

5. ATM (Asynchronous Transfer Mode)

The Data Link Layer plays a crucial role in ensuring reliable data transfer between nodes, and is responsible for:

1. Frame assembly and disassembly

2. Error detection and correction

3. Flow control and congestion avoidance

4. Medium access control and collision detection

In the context of blockchain, the Data Link Layer is responsible for ensuring that data, such as transactions and blocks, is transmitted accurately and reliably between nodes in the network, which is critical for maintaining the integrity of the blockchain.