TABLE OF CONTENTS TCP/IP is the most complex of any of the Internet protocols used by the AirDrop we've discussed thus far. Nebulous is a good word when it comes to describing the amount of information in print that talks about various aspects of TCP/IP. I'm going to take the Jack Webb approach and only give you TCP/IP facts that you need to use TCP/IP with an AirDrop.
The TCP/IP implementation that is effected by the AirDrop 802.11b driver is based on the TCP/IP code that was written for the series of EDTP wired Ethernet devices. The TCP/IP code I will describe was designed to conserve both microcontroller program memory and microcontroller data memory space. Thus, the AirDrop TCP/IP stack you will be introduced to here is a very minimal TCP/IP model. The AirDrop TCP/IP firmware is fashioned as a Telnet server that echoes characters it receives.
Just like all of the other internet protocols we've looked at up to this point, the TCP/IP module of the AirDrop 802.11b driver is called from the get_frame function. Every piece of code associated with the AirDrop 802.11b driver's TCP/IP function is listed in Code Snippet 14.1.
As you can see in Code Snippet 14.1, the Ethernet type field identifies the frame inside its data area as an IP frame and once that fact is established, the AirDrop 802.11b driver examines the IP protocol field inside the IP header. If the value in the IP protocol field of the IP header...
