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Important: This document is part of the Legacy section of the ADC Reference Library. This information should not be used for new development.
Current information on this Reference Library topic can be found here:
Use a High-Level Network Protocol
Make sure you use the Datagram Delivery Protocol (DDP), or a higher AppleTalk protocol based on DDP, like the AppleTalk Transaction Protocol (ATP), AppleTalk Data Stream Protocol (ADSP), or the PPC Toolbox. Be warned that Link Access Protocol (LAP) packets do not make it across bridges to other AppleTalk networks. In addition, don't broadcast; broadcast packets are not forwarded by bridges (broadcasting using protocols above LAP is discouraged, anyway).
Use Name Binding
As usual, use the Name-Binding Protocol (NBP) to announce your presence on the network, as well as to find other entities on the network. Pay special attention to zone name fields; the asterisk (as in "MyLaser:LaserWriter:*") in a name you look up is now important; it means "my zone only" (see the Zone Information Protocol (ZIP) chapter of Inside AppleTalk and the AppleTalk Manager chapter of Inside Macintosh Volume VI for information on finding out what other zones exist). The zone field should always be an asterisk when registering a name.
Pay Attention to Network Number Fields
When handling the network addresses returned by
Do not assume that there are no routers on the network if your network number
is zero. With AppleTalk Remote Access, you can be on network zero and be
connected to a remote network. Network applications should look at the
Watch for Out-Of-Sequence and Non-Exactly-Once Requests
Due to a "race" condition on an internet, it's possible for an exactly-once ATP packet to slip through twice; to keep this from happening, send a sequence number as part of the data with each ATP packet; whenever you make a request, bump the sequence number, and never honor an old sequence number. If you use ADSP or the PPC Toolbox, the protocol will handle out-of-sequence packets and will always deliver data to the client in order.
Inside Macintosh, Volumes II, V, VI, The AppleTalk Manager
Technical Note M.NW.AppleTalk2Mac, AppleTalk Phase 2 on the Macintosh
Technical Note M.NW.AppleTalkTimer, AppleTalk Timers Explained
Technical Note M.NW.AppleTalk2, What's New With AppleTalk Phase 2