Re: [Discuss-gnuradio] Tun/Tap Problem while Running tunnel.py while wireshark recognizes

[Karan Talasila]

Hi Jay and Tom,

                        we too are having similar issues in communicating between two USRP's using tunnel.py. we fiddled a lot with the gain values, changed frequencies, modified delay variables in the code but found that even though there is pretty good full duplex communication of packets between the USRP's, the ping command is not giving a  good output. we tried and received a minimum ping packet loss of 60%. we couldn't get better than that with all the modifications we tried. we thought that the ping is not receiving the icmp back in time so it is showing as a false packet because the usrp packets reception on both ends is fine. 

Any suggestions will be very helpful. Thank You.

On Mon, Jun 10, 2013 at 8:00 PM, Jay Prakash <address@hidden> wrote:

Yes I have tested using different frequency.No help.

And while debugging I figured out that PHY layer receives the packet from transmitter sent as ping ICMP packets and decodes the sender's address.

After that it writes to the tun/tap. But tun/tap reply is unavailable.

Ie there is some problem in tun/tap and PHY layer interface.

How to figure this out?

Jay Prakash 

Senior Undergraduate 

Electronics Engineering

IIT (BHU)

VARANASI

+91-9559475258

http://about.me/jay.prakash/

http://www.linkedin.com/profile/view?id=91120191&trk=hb_tab_pro_top

On Mon, Jun 10, 2013 at 7:13 PM, Tom Rondeau <address@hidden> wrote:

On Thu, Jun 6, 2013 at 3:22 PM, Jay Prakash
<address@hidden> wrote:
> We are working on establishing a tunnel for MAC protocol design using
> tunnel.py given as example in GNU Radio but are unable to receive ping reply
> from the other node.
>
> We created tun/tap interface using ./tunnel.py -f 990M and ipconfig
> 192.168.200.1 on Machine A connected to N210 series of USRP.
> and ./tunnel.py -f 990M and ifconfig 192.168.200.2 on machine B.
>
> 1. Now on pinging machine B from A we can see ping packets being sent to B
> by A using wireshark, but there is no reply on node A.
>
> 2. We went into details and saw there were ARQ requests from B repetitively.
> I manually added the mac address to update the table.
> Now ARQ request ceased to exist but still there were no replies on A.
>
>
> 3. Since we knew the Packaging details of ICMP we read the packets being
> received by B and found the exact source address of A from the frame. It
> means message have been successfully decoded by the destination and it knows
> whom to reply for the ping but still I don't find any reception confirmation
> on source side.
>
> What may be the possible problems?USRP antenna gain?Packets collision?
>
> In short we are unable to use tunnely.py  and are seeking for possible
> causes.
>
> Jay Prakash
> Senior Undergraduate

You could be having gain issues. Test this using the standard
uhd_siggen and uhd_fft programs to understand what settings give you
the best gain.

Also, try using different frequencies for transmit and receive (use
the -h on the command line to figure out how to do this).

Tom

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--
Regards
Karan Talasila