Apple Printer Access Protocol
Apple Printer Access Protocol ( APAP , also Printer Access Protocol , PAP ) is a proprietary network protocol that enables computers to access PAP-enabled printers over a network. The protocol is mainly found on the client side on Apple computers with the Mac OS or macOS operating systems, but other operating systems also have PAP clients integrated. The extra effort to equip the printer with AppleTalk and PAP has only paid off with printers in higher price ranges. Therefore, with a few exceptions, it is implemented almost exclusively by laser printers and film imagesetters.
Due to the underlying NBP and ZIP protocols, addressing a printer under Mac OS is a very simple process that is done using the Select utility . A bidirectional data connection is established to the printer so that the user is informed of the status of the printer via status messages from the printer (no paper, data processing, printing), even without physical presence at the printer.
As with the AFP , there are PAP-enabled print server as software from other vendors, so is older Novell - Netware versions a powerful PAP server at. The CAP software and Netatalk also have a PAP server.
PAP was gradually replaced by LPR and later IPP because higher data transmission speeds are possible via TCP / IP than via AppleTalk.
The AppleTalk protocol stack
The AppleTalk protocols can be divided into several layers that form a protocol stack . The protocols can be classified in the OSI reference model as follows :
| OSI layer | AppleTalk protocol stack | ||||||
| 7th | AFP | PAP | |||||
| 6th | |||||||
| 5 | ZIP | ASP | ADSP | ||||
| 4th | ATP | AEP | NBP | RTMP | |||
| 3 | DDP | ||||||
| 2 | LLAP | ELAP | TLAP | FDDI | ← AARP | ||
| 1 | LocalTalk |
Ethernet driver |
Token Ring Driver |
FDDI driver |
|||
literature
- Gursharan S. Sidhu, Richard F. Andrews, Alan B. Oppenheimer: Inside AppleTalk. 2nd Edition. Addison-Wesley, Reading 1990, ISBN 0-201-55021-0 .
- Apple Computer, Inc. (Ed.): Inside Macintosh: Networking. Addison-Wesley, Reading 1994, ISBN 0-201-62269-6 (Chapter 1 Introduction to AppleTalk. ).
Web links
- Inside AppleTalk - original specification from AppleTalk and PAP (PDF, English)
- Netatalk - an open source AFP server for Unix operating systems with PAP support (English)
credentials
- ↑ Only up to version 10.5, see Knowledgebase entry HT3771 at Apple
- ↑ Support article at Apple regarding reduced printing speed via TCP / IP (English)