4.4BSD Edition .AU Samuel J. Leffler, William N. Joy, Robert S. Fabry, and Michael J. Karels .AI Computer Systems Research Group Computer Science Division Department of Electrical Engineering and Computer Science University of California, Berkeley Berkeley, CA 94720 .AB .FS * UNIX is a trademark of Bell Laboratories. .FE This report describes the internal structure of the networking facilities developed for the 4.4BSD version of the UNIX* operating system for the VAX\(dg. These facilities .FS \(dg DEC, VAX, DECnet, and UNIBUS are trademarks of Digital Equipment Corporation. .FE are based on several central abstractions which structure the external (user) view of network communication as well as the internal (system) implementation.

The report documents the internal structure of the networking system. The ``Berkeley Software Architecture Manual, 4.4BSD Edition'' (PSD:5) provides a description of the user interface to the networking facilities.

Revised .AE

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.OH 'Networking Implementation Notes''SMM:13-%' .EH 'SMM:13-%''Networking Implementation Notes' .bp

"TABLE OF CONTENTS"

 "1. Introduction" 

 "2. Overview" 

 "3. Goals 

 "4. Internal address representation" 

 "5. Memory management" 

 "6. Internal layering 6.1. Socket layer
6.1.1. Socket state
6.1.2. Socket data queues
6.1.3. Socket connection queuing
6.2. Protocol layer(s)
6.3. Network-interface layer
6.3.1. UNIBUS interfaces

 "7. Socket/protocol interface" 

 "8. Protocol/protocol interface" 8.1. pr_output
8.2. pr_input
8.3. pr_ctlinput
8.4. pr_ctloutput

 "9. Protocol/network-interface interface" 9.1. Packet transmission
9.2. Packet reception

 "10. Gateways and routing issues 10.1. Routing tables
10.2. Routing table interface
10.3. User level routing policies

 "11. Raw sockets" 11.1. Control blocks
11.2. Input processing
11.3. Output processing

 "12. Buffering and congestion control" 12.1. Memory management
12.2. Protocol buffering policies
12.3. Queue limiting
12.4. Packet forwarding

 "13. Out of band data" 

 "14. Trailer protocols" 

 Acknowledgements 

 References .bp
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