Don't you know the network layer switch?

Network layer switches, also known as Layer 3 switches, operate at the network layer (Layer 3) of the OSI model. Unlike data link layer switches (Layer 2 switches) which make forwarding decisions based on MAC addresses, Layer 3 switches make routing decisions based on IP addresses. The following is an overview of network layer switches:

Activity:

Routing Decisions: Layer 3 switches use routing algorithms to make forwarding decisions based on the packet's destination IP address. They maintain a routing table that maps IP addresses to next-hop routers or directly connected networks.

Packet forwarding: When a packet reaches a Layer 3 switch, it checks the destination IP address and consults its routing table to determine the appropriate outgoing interface to forward the packet. Layer 3 switches can route traffic between different IP subnets within the same network or between different networks.

IP Address Resolution: Layer 3 switches can perform IP address resolution (similar to ARP in Layer 2 switches), mapping IP addresses to MAC addresses in order to communicate with devices on the same subnet.

Feature:

Inter-VLAN routing: Layer 3 switches support inter-VLAN routing, allowing them to route traffic between different VLANs without the need for external routers. This feature enhances network segmentation and allows for more efficient use of network resources.

Quality of Service (QoS): Layer 3 switches can prioritize certain types of traffic based on IP precedence or DiffServ tagging, ensuring critical applications receive adequate bandwidth and quality of service.

Access Control Lists (ACLs): Layer 3 switches often support ACLs, allowing network administrators to control traffic based on criteria such as source/destination IP address, protocol, and port. ACLs can be used for security enforcement, traffic filtering, and policy implementation.

Dynamic routing protocols: Layer 3 switches can support dynamic routing protocols such as OSPF (Open Shortest Path First), RIP (Routing Information Protocol) and BGP (Border Gateway Protocol) for automatic route discovery and network aggregation.

Advantage:

Efficient routing: Layer 3 switches can route traffic based on IP address, allowing for more efficient use of network resources and enabling communication between different IP subnets.

Reduced broadcast domains: Inter-VLAN routing helps reduce the size of broadcast domains, minimizing broadcast traffic and improving network performance and security.

Scalability: Layer 3 switches can scale to support larger networks with multiple IP subnets and VLANs, providing high-performance routing capabilities for complex network environments.

Flexibility: Layer 3 switches provide flexibility in network design and topology, allowing dynamic routing, network segmentation and traffic prioritization based on business needs.

Limitation:

Complexity: Layer 3 switches can be more complex to configure and manage than Layer 2 switches, especially in environments with multiple VLANs and routing protocols.

Cost: Layer 3 switches tend to be more expensive than Layer 2 switches because of their advanced routing capabilities and additional features.

Processing overhead: Routing decisions in Layer 3 switches involve more processing overhead compared to Layer 2 switching, which can impact packet forwarding performance in high-throughput environments.

In summary, network layer switches provide advanced routing capabilities and enhanced functionality compared to data link layer switches, making them suitable for medium to large networks where efficient IP routing, network segmentation and traffic management are critical.