MTU Size

GNU Radio
1

Hi all,
I’m currently getting overflow errors that I believe could be remedied
by
increasing the MTU size.
Is there a way to change the recv_frame_size and send_frame_size in
Python?

I’ve read the Transport Application Notes and some old emails to this
list,
but I still can’t figure out how to pass these parameters to the USRP
objects. Any help is greatly appreciated!

-Alex

2

More specifically, I’ve tried changing the device address with:
device_addr=“addr0=10.1.1.105, recv_frame_size=4096,
send_frame_size=4096”
but when running the program, both the recv_frame_size and
send_frame_size
are still 1472 bytes.
I’ve also configured my network to be able to handle frames of size
4096,
and have had this working with C++ code. However, the Python code
doesn’t
work as I would expect. It seems not to make a difference whether I
specify
the frame size or not.

3

On 07/23/2012 09:40 AM, Alexander O. wrote:

More specifically, I’ve tried changing the device address with:
device_addr=“addr0=10.1.1.105, recv_frame_size=4096, send_frame_size=4096”
but when running the program, both the recv_frame_size and send_frame_size
are still 1472 bytes.
I’ve also configured my network to be able to handle frames of size 4096,
and have had this working with C++ code. However, the Python code doesn’t
work as I would expect. It seems not to make a difference whether I specify
the frame size or not.

Its the same device args, so python/c++ it shouldnt make a difference.

The driver is however testing if it can handle that MTU by sending test
packets. Perhaps its still a network configuration issue?

Also, you should be able to

uhd_usrp_probe --args=“addr0=10.1.1.105, recv_frame_size=4096,
send_frame_size=4096”

and still see the same issue.

-josh

4

Josh was correct; it was the network. Specifically, the network switch
wasn’t configured to save its settings after a reboot… Thank you both
for
the help!

-Alex

5

On 23 Jul 2012 13:05, Josh B. wrote:

On 07/23/2012 09:40 AM,
Alexander O. wrote:

More specifically, I’ve tried changing
the device address with: device_addr=“addr0=10.1.1.105,
recv_frame_size=4096, send_frame_size=4096” but when running the
program, both the recv_frame_size and send_frame_size are still 1472
bytes. I’ve also configured my network to be able to handle frames of
size 4096, and have had this working with C++ code. However, the Python
code doesn’t work as I would expect. It seems not to make a difference
whether I specify the frame size or not.

Its the same device args,
so python/c++ it shouldnt make a difference.

The driver is however
testing if it can handle that MTU by sending test
packets. Perhaps its
still a network configuration issue?

Also, you should be able to

uhd_usrp_probe --args="addr0=10.1.1.105, recv_frame_size=4096,

send_frame_size=4096"

and still see the same issue.

-josh

Lots of network cards don’t handle jumbograms, even if you
configure them to do so.