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Routing works at the network layer.
According to the Routing Table data
Routing. Routing**.
Switching works at the data link layer.
According to the "MAC Address Table" ** data.
Hardware**. Why doesn't the IP layer verify the data for errors?
Because the network layer is "best effort to transmit the packets completely", error detection is already implemented by the data link layer, and there is no need for another verification at the IP layer. Advantages: It is not responsible for error detection and correction, so it can achieve high transmission performance. Disadvantages: The IP layer is not responsible for error detection, so error detection can only be detected at the transport layer or application layer, which increases the time to correct errors. Just imagine, if two PCs communicate across the Internet, there are many routers between them, PC1 sends a packet to PC2, after arriving at the first router, because the original layer 2 protocol is an ethernet frame, the WAN needs to use HDLC or PPP protocol, if in this ** process, the packet has an error:
1. The IP layer does not do error verification, so after the second router receives the data through the WAN protocol (HDLC, PPP, etc.), as long as the data link layer is normal, it will not be able to know whether the received IP packet is correct, and the error will continue to be passed on until PC2, and then retransmitted. This process wastes network bandwidth and the resources of several routers in between.
2. If the IP can realize the error verification function, then when the second router arrives, router 2 will no longer continue to send error packets, and the error will be terminated. However, the bit error rate of network transmission is extremely low, so there is no need to do another verification at the IP layer