source: rtems-docs/networking/network_task_structure.rst @ b412038

4.115am
Last change on this file since b412038 was b412038, checked in by Chris Johns <chrisj@…>, on 04/11/16 at 03:53:58

Clean up and review of Networking User Guide.

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1.. COMMENT: Written by Eric Norum
2.. COMMENT: COPYRIGHT (c) 1988-2002.
3.. COMMENT: On-Line Applications Research Corporation (OAR).
4.. COMMENT: All rights reserved.
5
6Network Task Structure and Data Flow
7####################################
8
9A schematic diagram of the tasks and message *mbuf* queues in a simple RTEMS
10networking application is shown in the following figure:
11
12.. image:: images/networkflow.jpg
13
14
15The transmit task for each network interface is normally blocked waiting for a
16packet to arrive in the transmit queue.  Once a packet arrives, the transmit
17task may block waiting for an event from the transmit interrupt handler.  The
18transmit interrupt handler sends an RTEMS event to the transmit task to
19indicate that transmit hardware resources have become available.
20
21The receive task for each network interface is normally blocked waiting for an
22event from the receive interrupt handler.  When this event is received the
23receive task reads the packet and forwards it to the network stack for
24subsequent processing by the network task.
25
26The network task processes incoming packets and takes care of timed operations
27such as handling TCP timeouts and aging and removing routing table entries.
28
29The 'Network code' contains routines which may run in the context of the user
30application tasks, the interface receive task or the network task.  A network
31semaphore ensures that the data structures manipulated by the network code
32remain consistent.
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