[USRP-users] X310 MTU frame size issue

Michael West michael.west at ettus.com
Thu Oct 23 22:40:39 EDT 2014


Hi Louis,

I noticed that for the benchmark_rate you are supplying the IP address and
for GRC you are not.  Try supplying the same args ("addr=192.168.40.2") in
the "Device Addr" field of the UHD USRP Source/Sink block you are using.

Regards,
Michael E. West

On Thu, Oct 23, 2014 at 6:31 PM, Louis Brown via USRP-users <
usrp-users at lists.ettus.com> wrote:

> Operating my X310 from a UHD source in GRC via 10GE yields a low MTU at
> startup:
>
> -----------------------------------------------
> linux; GNU C++ version 4.8.3 20140911 (Red Hat 4.8.3-7); Boost_105400;
> UHD_003.008.000-6-gbde8e9a3
> -- X300 initialization sequence...
> -- Determining maximum frame size... 2188 bytes.
> UHD Warning:
>     For this connection, UHD recommends a send frame size of at least 8000
> for best
>     performance, but your system's MTU will only allow 2188.
>     This will negatively impact your maximum achievable sample rate.
> -----------------------------------------------
>
> My MTU for the 10GE interface is 9000 (verified with ifconfig), and when I
> run benchmark_rate it finds the correct MTU:
>
> ------------------------------------------------
> ./benchmark_rate --rx_rate 200E6 --args "addr=192.168.40.2"
> linux; GNU C++ version 4.8.3 20140911 (Red Hat 4.8.3-7); Boost_105400;
> UHD_003.008.000-6-gbde8e9a3
>
> Creating the usrp device with: addr=192.168.40.2...
> -- X300 initialization sequence...
> -- Determining maximum frame size... 8000 bytes.
> -----------------------------------------------
>
> So is this a GR issue or a UHD issue, or a combination?
>
> Thanks,
> Lou
> KD4HSO
>
>
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> USRP-users mailing list
> USRP-users at lists.ettus.com
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>
>
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