source: rtems-docs/networking/network_task_structure.rst @ 735de5f

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1Network Task Structure and Data Flow
2####################################
3
4A schematic diagram of the tasks and message *mbuf* queues in a
5simple RTEMS networking application is shown in the following
6figure:
7
8.. image:: images/networkflow.jpg
9
10
11The transmit task  for each network interface is normally blocked waiting
12for a packet to arrive in the transmit queue.  Once a packet arrives, the
13transmit task may block waiting for an event from the transmit interrupt
14handler.  The transmit interrupt handler sends an RTEMS event to the transmit
15task to indicate that transmit hardware resources have become available.
16
17The receive task for each network interface is normally blocked waiting
18for an event from the receive interrupt handler.  When this event is received
19the receive task reads the packet and forwards it to the network stack
20for subsequent processing by the network task.
21
22The network task processes incoming packets and takes care of
23timed operations such as handling TCP timeouts and
24aging and removing routing table entries.
25
26The ‘Network code’ contains routines which may run in the context of
27the user application tasks, the interface receive task or the network task.
28A network semaphore ensures that
29the data structures manipulated by the network code remain consistent.
30
31.. COMMENT: Written by Eric Norum
32
33.. COMMENT: COPYRIGHT (c) 1988-2002.
34
35.. COMMENT: On-Line Applications Research Corporation (OAR).
36
37.. COMMENT: All rights reserved.
38
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