Re: [Discuss-gnuradio] # of UDP packet

[Marcus Müller]

Hi SangHyuk,

Your computer sees dropped packets during benchmark_rate --rx_rate 25000000, and that means that your computer is too slow, you have a broken network card or a very strange firewall. In any case, you will need to solve the underlying issue before you can use your USRP at 25MS/s. It's absolutely no use to discuss anything if your computer can't keep up with the sample rate; all you do cannot work.

Also, we have already discussed with you multiple times that benchmark_tx is not what you should be using, and that you should have a look at the ofdm_{rx,tx,loopback}.grc examples.

I'm also relatively confident that you were included in discussions where we explained that the "logical" over-the-air packets are completely unrelated to the Gigabit ethernet packets. They are really just used to transport the samples from PC to USRP (or the other way), and the fact that these samples are part of packets over the air is a "higher level" one. The two kinds of packets (ethernet vs. air) have nothing to do with each other.

Best regards,
Marcus

On 10.04.2016 14:04, SangHyuk Kim wrote:

Hi all,

I'm observing packet moving using wireshark.

I used benchmark_rate --rx-rate 25000000 (10 seconds) and result like below:

Using Device: Single USRP:
  Device: USRP2 / N-Series Device
  Mboard 0: N210r4
  RX Channel: 0
    RX DSP: 0
    RX Dboard: A
    RX Subdev: CBX RX
  TX Channel: 0
    TX DSP: 0
    TX Dboard: A
    TX Subdev: CBX TX

Testing receive rate 25.000000 Msps on 1 channels
DD
Benchmark rate summary:
  Num received samples:    249942924
  Num dropped samples:     18513
  Num overflows detected:  0
  Num transmitted samples: 0
  Num sequence errors:     0
  Num underflows detected: 0

And result of wireshark tool described:

# of total packets = 463,471

(1599 packets are setting packet, which is 60~78 bytes and the others 1514 bytes packets)

i) How can I calculate # of total packets ? Are there packets made by USRP ?

Also I used benchmark_tx.py -f 1.18G -m qam16 -W 25000000 -M 200000000

I counted # of sending packets and compare it with wireshark.

printed # of packet on terminal = about 80,000 and wireshark = about 400,000

Even I make 400 bytes packet, wireshark captured 1512 bytes outgoing packet.

ii) How packet transport through LAN cable between host PC and USRP?

Thanks.

 

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