Thread: Data link / Application layers

Generally, the application layer is a packet within a bigger packet that is the data link. The purpose of the data link is to ensure the packet arrives correctly to the right application and complete with the correct content.

I don't have any direct example, but the data structure may be something like this:

Code:

struct header
{
    int magic;      // A magic number that indicates the start of a packet. 
    int pktsize;    // Size of the payload (application) data. 
    int hdrsize;   // Size of this header 
    int pktcsum;  // checksum of the payload data.
    int recipient;  // Who it's for. 
    int sender;    // Who sent it
    int hdrcsum;  // checksum of the header (it's last, so we can calculate it from the other components)
};

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Mats