How does WiFi 802.11 correspond to 802.3

802.11 This is a IEEE One designated by the alliance Link layer and physical layer protocol specifications , and 802.3 ethernet Link layer protocol It belongs to the same layer protocol specification .

Why do we need this agreement , Should be different network Communication between cards is required , Their clock , transmission speed The transmission format will be different if the same standard Between different network cards It will waste communication resources or not be able to communicate at all . 

The physical layer ： When data is locally addressed id, Note that it is not network addressable id , Network addressing depends on ip. What needs to be done at this level is to use cpu Terminal you or DMA technology To receive data in stream form , This is the concept that data has no format encapsulation .

The link layer ： This layer has the concept of data structure , Why link layer is needed , Because in the physical layer There is no mechanism to check and retransmit data . So the link layer needs to be done here , ppp,slip Etc .

How do different link connections correspond to kernel Medium The data transfer Of the structure . such as 802.11 How and 802.3 ethernet Corresponding .

such as wifi When the network card receives a packet stay driver layer He will Remove 802.11 And put the data data Decrypt （ Be careful 802.11 Well ethernet head 802.3 Information about Main time ethternet type Save in data Inside ） And then according to kernel skb struct After group number Pass to kernel network modular Then process the data of each layer .

Be careful 802.11 My bag is going to kernel The preceding tense carries on and 802.3 Structural transformation , So if you're in ethernet Grab at the mouth wifi Turning around packets when I can't see 802.11 The head of the .