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rtems-docs/networking/testing_the_driver.rst
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Testing the Driver
##################
Preliminary Setup
=================
The network used to test the driver should include at least:
- The hardware on which the driver is to run.
It makes testing much easier if you can run a debugger to control
the operation of the target machine.
- An Ethernet network analyzer or a workstation with an
‘Ethernet snoop’ program such as ``ethersnoop`` or``tcpdump``.
- A workstation.
During early debug, you should consider putting the target, workstation,
and snooper on a small network by themselves. This offers a few
advantages:
- There is less traffic to look at on the snooper and for the target
to process while bringing the driver up.
- Any serious errors will impact only your small network not a building
or campus network. You want to avoid causing any unnecessary problems.
- Test traffic is easier to repeatably generate.
- Performance measurements are not impacted by other systems on
the network.
Debug Output
============
There are a number of sources of debug output that can be enabled
to aid in tracing the behavior of the network stack. The following
is a list of them:
- mbuf activity
There are commented out calls to ``printf`` in the file``sys/mbuf.h`` in the network stack code. Uncommenting
these lines results in output when mbuf’s are allocated
and freed. This is very useful for finding memory leaks.
- TX and RX queuing
There are commented out calls to ``printf`` in the file``net/if.h`` in the network stack code. Uncommenting
these lines results in output when packets are placed
on or removed from one of the transmit or receive packet
queues. These queues can be viewed as the boundary line
between a device driver and the network stack. If the
network stack is enqueuing packets to be transmitted that
the device driver is not dequeuing, then that is indicative
of a problem in the transmit side of the device driver.
Conversely, if the device driver is enqueueing packets
as it receives them (via a call to ``ether_input``) and
they are not being dequeued by the network stack,
then there is a problem. This situation would likely indicate
that the network server task is not running.
- TCP state transitions
In the unlikely event that one would actually want to see
TCP state transitions, the ``TCPDEBUG`` macro can be defined
in the file ``opt_tcpdebug.h``. This results in the routine``tcp_trace()`` being called by the network stack and
the state transitions logged into the ``tcp_debug`` data
structure. If the variable ``tcpconsdebug`` in the file``netinet/tcp_debug.c`` is set to 1, then the state transitions
will also be printed to the console.
Monitor Commands
================
There are a number of command available in the shell / monitor
to aid in tracing the behavior of the network stack. The following
is a list of them:
- ``inet``
This command shows the current routing information for the TCP/IP stack. Following is an
example showing the output of this command.
.. code:: c
Destination Gateway/Mask/Hw Flags Refs Use Expire Interface
10.0.0.0 255.0.0.0 U 0 0 17 smc1
127.0.0.1 127.0.0.1 UH 0 0 0 lo0
In this example, there is only one network interface with an IP address of 10.8.1.1. This
link is currently not up.
Two routes that are shown are the default routes for the Ethernet interface (10.0.0.0) and the
loopback interface (127.0.0.1).
Since the stack comes from BSD, this command is very similar to the netstat command. For more
details on the network routing please look the following
URL: (http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/network-routing.html)
For a quick reference to the flags, see the table below:
‘``U``’
Up: The route is active.
‘``H``’
Host: The route destination is a single host.
‘``G``’
Gateway: Send anything for this destination on to this remote system, which
will figure out from there where to send it.
‘``S``’
Static: This route was configured manually, not automatically generated by the
system.
‘``C``’
Clone: Generates a new route based upon this route for machines we connect
to. This type of route is normally used for local networks.
‘``W``’
WasCloned: Indicated a route that was auto-configured based upon a local area
network (Clone) route.
‘``L``’
Link: Route involves references to Ethernet hardware.
- ``mbuf``
This command shows the current MBUF statistics. An example of the command is shown below:
.. code:: c
************ MBUF STATISTICS \************
mbufs:4096 clusters: 256 free: 241
drops: 0 waits: 0 drains: 0
free:4080 data:16 header:0 socket:0
pcb:0 rtable:0 htable:0 atable:0
soname:0 soopts:0 ftable:0 rights:0
ifaddr:0 control:0 oobdata:0
- ``if``
This command shows the current statistics for your Ethernet driver as long as the ioctl hook``SIO_RTEMS_SHOW_STATS`` has been implemented. Below is an example:
.. code:: c
************ INTERFACE STATISTICS \************
\***** smc1 \*****
Ethernet Address: 00:12:76:43:34:25
Address:10.8.1.1 Broadcast Address:10.255.255.255 Net mask:255.0.0.0
Flags: Up Broadcast Running Simplex
Send queue limit:50 length:0 Dropped:0
SMC91C111 RTEMS driver A0.01 11/03/2002 Ian Caddy (ianc@microsol.iinet.net.au)
Rx Interrupts:0 Not First:0 Not Last:0
Giant:0 Runt:0 Non-octet:0
Bad CRC:0 Overrun:0 Collision:0
Tx Interrupts:2 Deferred:0 Missed Hearbeat:0
No Carrier:0 Retransmit Limit:0 Late Collision:0
Underrun:0 Raw output wait:0 Coalesced:0
Coalesce failed:0 Retries:0
\***** lo0 \*****
Address:127.0.0.1 Net mask:255.0.0.0
Flags: Up Loopback Running Multicast
Send queue limit:50 length:0 Dropped:0
- ``ip``
This command show the IP statistics for the currently configured interfaces.
- ``icmp``
This command show the ICMP statistics for the currently configured interfaces.
- ``tcp``
This command show the TCP statistics for the currently configured interfaces.
- ``udp``
This command show the UDP statistics for the currently configured interfaces.
Driver basic operation
======================
The network demonstration program ``netdemo`` may be used for these tests.
- Edit ``networkconfig.h`` to reflect the values for your network.
- Start with ``RTEMS_USE_BOOTP`` not defined.
- Edit ``networkconfig.h`` to configure the driver
with an
explicit Ethernet and Internet address and with reception of
broadcast packets disabled:
Verify that the program continues to run once the driver has been attached.
- Issue a ‘``u``’ command to send UDP
packets to the ‘discard’ port.
Verify that the packets appear on the network.
- Issue a ‘``s``’ command to print the network and driver statistics.
- On a workstation, add a static route to the target system.
- On that same workstation try to ‘ping’ the target system.
Verify that the ICMP echo request and reply packets appear on the net.
- Remove the static route to the target system.
Modify ``networkconfig.h`` to attach the driver
with reception of broadcast packets enabled.
Try to ‘ping’ the target system again.
Verify that ARP request/reply and ICMP echo request/reply packets appear
on the net.
- Issue a ‘``t``’ command to send TCP
packets to the ‘discard’ port.
Verify that the packets appear on the network.
- Issue a ‘``s``’ command to print the network and driver statistics.
- Verify that you can telnet to ports 24742
and 24743 on the target system from one or more
workstations on your network.
BOOTP/DHCP operation
====================
Set up a BOOTP/DHCP server on the network.
Set define ``RTEMS USE_BOOT`` in ``networkconfig.h``.
Run the ``netdemo`` test program.
Verify that the target system configures itself from the BOOTP/DHCP server and
that all the above tests succeed.
Stress Tests
============
Once the driver passes the tests described in the previous section it should
be subjected to conditions which exercise it more
thoroughly and which test its error handling routines.
Giant packets
-------------
- Recompile the driver with ``MAXIMUM_FRAME_SIZE`` set to
a smaller value, say 514.
- ‘Ping’ the driver from another workstation and verify
that frames larger than 514 bytes are correctly rejected.
- Recompile the driver with ``MAXIMUM_FRAME_SIZE`` restored to 1518.
Resource Exhaustion
-------------------
- Edit ``networkconfig.h``
so that the driver is configured with just two receive and transmit descriptors.
- Compile and run the ``netdemo`` program.
- Verify that the program operates properly and that you can
still telnet to both the ports.
- Display the driver statistics (Console ‘``s``’ command or telnet
‘control-G’ character) and verify that:
# The number of transmit interrupts is non-zero.
This indicates that all transmit descriptors have been in use at some time.
# The number of missed packets is non-zero.
This indicates that all receive descriptors have been in use at some time.
Cable Faults
------------
- Run the ``netdemo`` program.
- Issue a ‘``u``’ console command to make the target machine transmit
a bunch of UDP packets.
- While the packets are being transmitted, disconnect and reconnect the
network cable.
- Display the network statistics and verify that the driver has
detected the loss of carrier.
- Verify that you can still telnet to both ports on the target machine.
Throughput
----------
Run the ``ttcp`` network benchmark program.
Transfer large amounts of data (100’s of megabytes) to and from the target
system.
The procedure for testing throughput from a host to an RTEMS target
is as follows:
# Download and start the ttcp program on the Target.
# In response to the ``ttcp`` prompt, enter ``-s -r``. The
meaning of these flags is described in the ``ttcp.1`` manual page
found in the ``ttcp_orig`` subdirectory.
# On the host run ``ttcp -s -t <<insert the hostname or IP address of the Target here>>``
The procedure for testing throughput from an RTEMS target
to a Host is as follows:
# On the host run ``ttcp -s -r``.
# Download and start the ttcp program on the Target.
# In response to the ``ttcp`` prompt, enter ``-s -t <<insert the hostname or IP address of the Target here>>``. You need to type the
IP address of the host unless your Target is talking to your Domain Name
Server.
To change the number of buffers, the buffer size, etc. you just add the
extra flags to the ``-t`` machine as specified in the ``ttcp.1``
manual page found in the ``ttcp_orig`` subdirectory.
.. COMMENT: Text Written by Jake Janovetz
.. COMMENT: COPYRIGHT (c) 1988-2002.
.. COMMENT: On-Line Applications Research Corporation (OAR).
.. COMMENT: All rights reserved.
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