Hi,

>From what I remember the tunnel.py scripts connect to 1 USRP.
If you run the script twice it is going to try and open a second
usrp_source and usrp_sink but you only have 1 USRP hooked up to your
computer.

If what you want to do is send packets on an interface then have those
packets go through the tunnel.py script, go through the air via the USRP
then get received at another USRP and go up the chain again then you either
need 2 USRPs OR you need to modify your scripts so that you have one script
that only sends packets (and therefore only has a usrp_sink) and one script
that only receives packets (and therefore only has a usrp_source).

Also, beware of having 2 virtual interfaces on the same machine.
If you try sending your packets from one to the other they'll most likely
go directly from one to the other through the linux stack and bypass your
tunnel scripts entirely.

I hope this is somewhat helpful,
Jawad

2016-09-13 0:01 GMT+02:00 Shao, Sihua <[email protected]>:

> Dear all,
>
> I'm trying to build two tunnel virtual Ethernet interfaces on a single PC
> using tunnel.py from "gnuradio/gr-digital/examples/ofdm". The PC has only
> one Ethernet interface card and is connecting to one USRP. What I did is
> opening two terminals and running tunnel.py on each of them. After I type
> the command "sudo ifconfig gr0 192.168.200.1" in a separate terminal, the
> first terminal running the 1st tunnel.py works well (i.e. the packets
> forwarded to gr0 got modulated and transmitted via USRP). However, after I 
> type
> the command "sudo ifconfig gr1 192.168.100.1" in another separate terminal,
> the first terminal running the 1st tunnel.py stop working and only the most
> recent created virtual interface (here is gr1) works well. Based on this
> observation, I guess the tunnel.py running in the 2nd terminal occupies
> some important resources that the tunnel.py running in the 1st terminal was
> utilizing. But I have no idea what exactly cause the tunnel.py running in
> the 1st terminal stop working.
>
> Please let me know your comments if you have been working on the similar
> problem.
>
> Best,
>
> Sihua Shao
> Ph.D Student
> Department of Electrical and Computer Engineering
> New Jersey Institute of Technology
>
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