Vlan forwarding process

During Vlan forwarding, untag is a common ethernet packet. The NIC of a common PC can identify such packets for communication. The structure of the tag packet is changed after the source mac address and the target mac address, 4-bytes vlan information is added, that is, the vlan tag header. Generally, the NIC of an ordinary PC cannot identify such packets; the following example describes the pc2 connected to inter e0/2 accessed by pc1 under inter e0/1; the data sent by pc1, the pvid vlan10 of inter0/1 encapsulates vlan10 and sends it to the switch. The switch finds that inter e0/2 allows vlan 10 Data to pass through, so the data is forwarded to inter e0/2, because vlan 10 on inter e0/2 is untagged, the switch removes the vlan10 mark on the data packet and sends it to pc2 as a normal package. In this case, pc1-> p2 follows vlan10; then, we analyze the process of pc2 returning packets to pc1. The data sent by pc2 is sent to the switch by the pvid vlan20 of inter0/2 encapsulation vlan20, the switch finds that inter e0/1 allows the data of vlan 20 to pass, so the data is forwarded to inter e0/1, because vlan 20 on inter e0/1 is untagged, the switch removes the vlan20 mark from the data packet and sends it to pc1 in the form of a normal package. In this case, pc2-> pc1 follows vlan20;