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First, µC/TCP-IP copies application-specified data from the application buffer into the application data region before writing network protocol header data to the protocol header region. After that, depending on the type of the packet being sent, each required layers will add its own protocol headers in the Protocols Headers Region of the Data Area. Starting from the highest layer to the lowest layer, all required headers are stacked on top of each other.
Network Buffer Sizes (to review)
µC/TCP-IP requires that network buffer sizes configured in net_dev_cfg.c satisfy the minimum and maximum packet frame sizes of network interfaces/devices.
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