Hi,
On 22/11/2018 16:20, Marcus D. Leech via USRP-users wrote:
On 11/22/2018 09:26 AM, Paul Boven via USRP-users wrote:
A simple flowgraph (see attached image) using RFNOC:Radio, RFNOC:DDC
and a QT GUI frequency, together with Device3, starts and runs but no
data is produced. Instead, it generates a lot of error messages,
"timeout on chan 0" and "ValueError: Bad CHDR or packet fragment".
Check your ethernet MTUs and the packet sizes setup in your device3
block. I had this issue the other day, and the MTU on my ethernet
interface had been set larger than it could actually support, resulting in
truncated-by-the-interface packets.
Thanks for the quick reply.
The MTU of the network doesn't seem to be the issue. I've tried on two
different network cards on my PC (both Intel 1G cards).
The MTU of the Ethernet card is set to 9000, and this is known to work.
uhd_usrp_probe chooses a packet size of 8000 bytes. When running tcpdump
at the same time, I can see that packets of 8000 bytes are being received.
It looks like it sends about 1 second of data in 8000 bytes packets from
UDP port 49153 to port 33894, and then the remaining traffic is just 16
byte packets being exchanged between PC and USRP.
Regards, Paul Boven.
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