Network Layer 2 (Data Link Layer)

Layer 2 operates at the data link level and is primarily responsible for communication between devices on the same local network (LAN). At this layer, data is packaged into frames and MAC (Media Access Control) addresses are used to identify devices on the network.

Some of the common Layer 2 devices include switches and bridges.

Layer 2 Key Features:

• Control access to the shared physical medium.
• Learn and maintain MAC address tables.
• Forward frames within the same LAN based on MAC addresses.
• Detect and correct errors in plots.

Network Layer 3 (Network Layer)

Layer 3 is one level higher in the OSI model and focuses on routing data between different networks. At this layer, data is packaged into packets and Internet Protocol (IP) addresses are used to identify both devices and networks.

Routers are key Layer 3 devices as they determine the best route for packets to reach their destination across interconnected networks.

Layer 3 Key Features:

• Routing packets between networks.
• Maintaining routing tables to determine the most efficient routes.
• IP address translation to route packets through NAT (Network Address Translation).
• Packet filtering for security and traffic control.

Differences between Network Layer 2 and Layer 3

The main differences between Layer 2 and Layer 3 networks lie in their scope and functionality:

1. Reach:

• Layer 2: Focuses on communication within the same local network (LAN) and does not cross multiple networks.
• Layer 3: Allows communication between different networks and is responsible for routing packets through multiple devices and interconnected networks.

2. Addresses used:

• Layer 2: Uses MAC addresses to identify devices on the same LAN.
• Layer 3: Uses IP addresses to identify both devices and networks, allowing communication over separate networks.

3. Key devices:

• Layer 2: The main devices are switches and bridges.
• Layer 3: The key devices are routers.