Layer 3 and 4 switches operate primarily at which model layers?

Layer 3 and 4 switches operate primarily at the Network and Transport layers of the OSI model. Layer 3 switches function by using logical addressing (such as IP addresses) to route packets between different networks, which is characteristic of the Network layer. They are capable of making forwarding decisions based on layer 3 information, allowing for traffic management and path selection based on the destination IP address.

Layer 4 switches, on the other hand, extend this functionality by incorporating session management and looking at transport layer protocols (like TCP and UDP). They can make decisions based on layer 4 information, such as port numbers, which enables a more refined control over the streamed packets, enhancing data flow and application performance.

This ability to handle "intelligent" traffic management at these layers makes Layer 3 and 4 switches vital in networks where efficient routing and switching are required, especially in environments that need varied levels of Quality of Service (QoS) based on the transport layer characteristics. This dual function helps manage not just where to send packets, but also how they are prioritized and managed across networks.