[USRP-users] X310 MTU frame size issue

Louis Brown rfengr00 at me.com
Fri Oct 24 12:16:25 EDT 2014


Regarding my previous post, I have found if I wait until the X310 link light goes from red to off, about 10 seconds, I can re-establish communication.  If I try to run my GRC flow when the link light is red, it finds the incorrect MTU.  So I guess the rule is, always wait until the link light is off until you re-run your flow graph.

Lou

On Oct 23, 2014, at 08:40 PM, Michael West <michael.west at ettus.com> wrote:

> 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:
>
>     Sent from iCloud
>
>         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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>
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