What is the fundamental distinction between a Layer 2 switch and a router?
The fundamental distinction between a Layer 2 switch and a router lies in their functions and the way they operate within a network.
1. Function:
- Layer 2 Switch: A Layer 2 switch is primarily responsible for forwarding data packets based on the MAC (Media Access Control) addresses of devices connected to its ports. It operates at the Data Link Layer (Layer 2) of the OSI model and is commonly used for local network switching.
- Router: A router, on the other hand, is responsible for forwarding data packets between different networks by examining the IP (Internet Protocol) addresses of packets. It operates at the Network Layer (Layer 3) of the OSI model and is used for interconnecting networks.
2. Scope:
- Layer 2 Switch: A Layer 2 switch operates within a single LAN (Local Area Network) and forwards packets between devices within that LAN. It does not participate in routing packets between different networks.
- Router: A router operates at the network level, allowing communication between different LANs or networks. It determines the optimal path for data packets to reach their destination across networks.
3. Addressing:
- Layer 2 Switch: A Layer 2 switch uses MAC addresses to forward packets. It maintains a MAC address table (also known as a CAM table) that maps MAC addresses to specific ports. When a switch receives a packet, it checks the destination MAC address in its table and forwards the packet to the appropriate port.
- Router: A router uses IP addresses to forward packets. It maintains a routing table that contains information about the network addresses of different networks. When a router receives a packet, it checks the destination IP address against its routing table and forwards the packet to the appropriate interface.
4. Broadcast Domains:
- Layer 2 Switch: A Layer 2 switch creates a single broadcast domain. Broadcasts and multicasts are flooded to all ports within the same LAN segment.
- Router: A router creates separate broadcast domains. It does not forward broadcasts or multicasts by default, which helps in controlling network traffic and improving network efficiency.
In summary, a Layer 2 switch operates within a single LAN, uses MAC addresses, and primarily forwards packets at the Data Link Layer, while a router interconnects networks, uses IP addresses, and forwards packets based on routing tables at the Network Layer.