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#1 2018-Jan-24 14:07:17

Registered: 2017-Sep-20
Posts: 18

Ustable connection

Hi, I have encountering an annoying issue with Warp3 with 802.11 reference design Version 1.7.4. The switch is Netgear Prosafe GS108 and two warp3 nodes connected to the switch on ETHB . The NIC on my laptop is configured as and I am using throughput_two_nodes.py, I have this error very often:

Initializing experiment

Resetting the network config for all nodes on network
Initializing W3-a-00810
ERROR:  Node W3-a-00809
    Node is not responding.  Please ensure that the
    node is powered on and is properly configured.

    Error: Max retransmissions without reply from node

Traceback (most recent call last):

  File "<ipython-input-160-e9e72a2c6b98>", line 1, in <module>
    runfile('C:/Python_Reference/examples/throughput_two_nodes.py', wdir='C:/Python_Reference/examples')

  File "C:\Users\CRR\Anaconda3\lib\site-packages\spyder\utils\site\sitecustomize.py", line 710, in runfile
    execfile(filename, namespace)

  File "C:\Users\CRR\Anaconda3\lib\site-packages\spyder\utils\site\sitecustomize.py", line 101, in execfile
    exec(compile(f.read(), filename, 'exec'), namespace)

  File "C:/Python_Reference/examples/throughput_two_nodes.py", line 70, in <module>
    nodes = util.init_nodes(nodes_config, network_config)

  File "C:\Python_Reference\wlan_exp\util.py", line 439, in init_nodes
    return util.init_nodes(nodes_config, network_config, node_factory, network_reset, output)

  File "C:\Python_Reference\wlan_exp\transport\util.py", line 98, in init_nodes
    (_, sn_str) = get_serial_number(node_dict['serial_number'], output=False)

TypeError: get_serial_number() got an unexpected keyword argument 'output'

But like 1 in 20 runs it can run the python script, but most of the time it doesn't work. Its frustrated for testing.

Thanks for the help.
Ruirong Chen



#2 2018-Jan-24 15:43:32

From: Mango Communications
Registered: 2006-Jul-03
Posts: 5159

Re: Ustable connection

A common source of this behavior is running the Python script before the node's ETH B interface has negotiated its link with the switch. When this happens the PC will not get an ARP response from the node and will flag the node's IP address as unresolved. This is especially bad on Windows, where the single ARP failure causes the OS to drop all packets for a given IP address for a while, even after the Ethernet link comes up. You can run "arp -a" to see if the OS believes your node's IP address is unreachable.

It's also worth trying different Ethernet cables - we have definitely see bad cables cause intermittent packet failures, even if the switch and node show a good link.



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