NetWorker Knowledge Corner|Easy to get an offer [Networker Interview Questions] What is the difference between a Layer 3 switch and a router?

【Interview Questions for Network Engineers】What is the difference between a Layer 3 switch and a router?

1. Different main functions

Layer 3 switch is a switch with some basic routing functions, and its main function is still data exchange.It has both data exchange and routing forwarding functions, but its main function is data exchange;

The router has only one main function of routing forwarding.

2. The applicable environment is different

The routing function of the Layer 3 switch is relatively simple, and it mainly faces simple LAN connections.

The main purpose of its use in the local area network is to provide fast data exchange function, to meet the application characteristics of frequent data exchange in the local area network.

A router is designed to meet different types of network connections. Its routing function is more reflected in the interconnection between different types of networks. Its main function is routing and forwarding.

It is not only suitable for LANs with the same protocol, but also for LANs and WANs with different protocols.

3. Different performance

From a technical point of view, routers and Layer 3 switches have obvious differences in packet switching operations.

The router generally exchanges data packets based on CPU, and the three-layer switch exchanges data packets through hardware forwarding;

After the Layer 3 switch routes the first data flow, it will generate a mapping table between MAC addresses and IP addresses (hardware forwarding table).When the same data flow passes through again, it will pass directly from the second layer according to the hardware forwarding table instead of calculating the forwarding path through the CPU again, which improves the efficiency of data packet forwarding and realizes fast forwarding.

The forwarding of the router uses the CPU to calculate and forward the route. All data packets need to be calculated and forwarded by the CPU, so the forwarding efficiency is lower than that of the switch. Now the router also has a hardware forwarding table, but the first one to passThe data packets still need to be calculated by the CPU.