# Why am I dropping data over the UDP network? **URL:** \ **Category:** GNU Radio\ **Created:** [July 11, 2014, 7:05pm UTC](https://www.ruby-forum.com/t/why-am-i-dropping-data-over-the-udp-network/230908 "2014-07-11T19:05:15Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![addis\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c4cdca/32.png) [@addis\_a](https://www.ruby-forum.com/u/addis_a)\ **Post date:** [July 11, 2014, 7:05pm UTC](https://www.ruby-forum.com/t/why-am-i-dropping-data-over-the-udp-network/230908/1 "2014-07-11T19:05:15Z")
Hey Everyone, I am sending a signal from one USRP to another USRP through a UDP network. It seems to work but I am getting data loss as gnu-radio runs the flow graph. Hopefully someone could help me with this problem? P.S. I have the sender side (RecieveStation.jpg) and the Reciever/Display side (RecieveDisplay.jpg) attached ---
**Author:** ![WardS\_Marcus\_D](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/ccd318/32.png) [@WardS\_Marcus\_D](https://www.ruby-forum.com/u/WardS_Marcus_D)\ **Post date:** [July 11, 2014, 7:36pm UTC](https://www.ruby-forum.com/t/why-am-i-dropping-data-over-the-udp-network/230908/2 "2014-07-11T19:36:49Z")
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**Author:** ![WardS\_Marcus\_D](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/ccd318/32.png) [@WardS\_Marcus\_D](https://www.ruby-forum.com/u/WardS_Marcus_D)\ **Post date:** [July 11, 2014, 7:39pm UTC](https://www.ruby-forum.com/t/why-am-i-dropping-data-over-the-udp-network/230908/3 "2014-07-11T19:39:48Z")
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**Author:** ![WardS\_Marcus\_D](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/ccd318/32.png) [@WardS\_Marcus\_D](https://www.ruby-forum.com/u/WardS_Marcus_D)\ **Post date:** [July 11, 2014, 7:51pm UTC](https://www.ruby-forum.com/t/why-am-i-dropping-data-over-the-udp-network/230908/4 "2014-07-11T19:51:07Z")
Funny that I was doing the exact same thing last night, and I’m also getting warnings on the receive end at only 500 ksps on a home LAN. Should the stream be vectorized before the UDP sink, and if so how long? I tried both stream and vectors but still get the warnings. Lou KD4HSO Ward, Marcus D. wrote > Hey Everyone, > > I am sending a signal from one USRP to another USRP through a UDP network. > It seems to work but I am getting data loss as gnu-radio runs the flow > graph. Hopefully someone could help me with this problem? > > P.S. I have the sender side (RecieveStation.jpg) and the Reciever/Display > side (RecieveDisplay.jpg) attached – View this message in context: [http://gnuradio.4.n7.nabble.com/Why-am-I-dropping-data-over-the-UDP-network-tp49283p49286.html](http://gnuradio.4.n7.nabble.com/Why-am-I-dropping-data-over-the-UDP-network-tp49283p49286.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![WardS\_Marcus\_D](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/ccd318/32.png) [@WardS\_Marcus\_D](https://www.ruby-forum.com/u/WardS_Marcus_D)\ **Post date:** [July 11, 2014, 7:55pm UTC](https://www.ruby-forum.com/t/why-am-i-dropping-data-over-the-udp-network/230908/5 "2014-07-11T19:55:53Z")
If I change the type to complex integer 16, you think I’ll have a better outcome? Seeing as if there is a way to change the type to complex 16, but I will have to incorporate converters. From: Marcus L. [[mailto:removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)] Sent: Friday, July 11, 2014 1:38 PM To: Ward, Marcus D. Cc: removed\_email\_address@domain.invalid Subject: Re: [Discuss-gnuradio] Why am I dropping data over the UDP network? Also, you’re sending data at 6.25Msps, with complex-float samples, which chews up: 6.25e6 x 8 bytes/second = 400Mbit/second, without accounting for headers and other overhead. You might want to re-think your architecture, if you’re going to be sending this data over the network. on Jul 11, 2014, Ward, Marcus D. \ wrote: Hey Everyone, I am sending a signal from one USRP to another USRP through a UDP network. It seems to work but I am getting data loss as gnu-radio runs the flow graph. Hopefully someone could help me with this problem? P.S. I have the sender side (RecieveStation.jpg) and the Reciever/Display side (RecieveDisplay.jpg) attached * * * ---
**Author:** ![WardS\_Marcus\_D](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/ccd318/32.png) [@WardS\_Marcus\_D](https://www.ruby-forum.com/u/WardS_Marcus_D)\ **Post date:** [July 14, 2014, 10:04pm UTC](https://www.ruby-forum.com/t/why-am-i-dropping-data-over-the-udp-network/230908/6 "2014-07-14T22:04:27Z")
The UDP sink doesn’t support complex int 16, so what would I be able to change the type to in order to come to a close solution for this problem? Also, I have lowered the sample rate to very small amounts such as 1e6, but I still lose packages on the receiving end. There is a 1-gigabit switch between the two USRP’s, so it is a very simple network. I don’t think the network is the problem. ---
**Author:** ![WardS\_Marcus\_D](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/ccd318/32.png) [@WardS\_Marcus\_D](https://www.ruby-forum.com/u/WardS_Marcus_D)\ **Post date:** [July 14, 2014, 10:09pm UTC](https://www.ruby-forum.com/t/why-am-i-dropping-data-over-the-udp-network/230908/7 "2014-07-14T22:09:13Z")
I forgot to add that the 1e6 data rate was going to a null sink. The data rate is only 1Mhz \* 4bytes \* 2 channels = 8M bytes per second to a null sink, which should be fine. Does anyone have any suggestions as to what settings I should have in my UDP source block in terms of payload size, buffer size, etc.? Thanks, Marcus ---
**Author:** ![WardS\_Marcus\_D](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/ccd318/32.png) [@WardS\_Marcus\_D](https://www.ruby-forum.com/u/WardS_Marcus_D)\ **Post date:** [July 12, 2014, 2:59am UTC](https://www.ruby-forum.com/t/why-am-i-dropping-data-over-the-udp-network/230908/8 "2014-07-12T02:59:49Z")
No, building vectors out of streams would (in the best case) change nothing, as you don’t send individual samples but always packets full of payloads. Also, if you have a hardware device defining your data rate, you will never need a throttle, and having one will most likely only introduce problems, so remove it from your flowgraph. All throttle really does is trying to achieve a given _average_ sample processing rate, and that interferes with the hardware _constantly_ providing a sample rate. A few numbers in my head: 500ksps = 500 \* 32kbps = 16000kbps, not very much for a gigabit ethernet! So I think it’s safe to assume that the physical network is not to blame here, and usually the CPU load, maybe introduced by network handling might be to blame, if this doesn’t happen with a null sink. Greetings, Marcus ---
**Author:** ![WardS\_Marcus\_D](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/ccd318/32.png) [@WardS\_Marcus\_D](https://www.ruby-forum.com/u/WardS_Marcus_D)\ **Post date:** [July 14, 2014, 10:15pm UTC](https://www.ruby-forum.com/t/why-am-i-dropping-data-over-the-udp-network/230908/9 "2014-07-14T22:15:11Z")
Hi Marcus, On 14.07.2014 22:01, Ward, Marcus D. wrote: > The UDP sink doesn’t support complex int 16, so what would I be able to change > the type to in order to come to a close solution for this problem? > It should, using the datatype “short”. > > Also, I have lowered the sample rate to very small amounts such as 1e6, but I > still lose packages on the receiving end. There is a 1-gigabit switch between the > two USRP’s, so it is a very simple network. I don’t think the network is the > problem. > I tend to agree, but dropped data indicates that either end (presumably > the receiving one) is having trouble getting the data out of the UDP > source fast enough. ---
**Author:** ![WardS\_Marcus\_D](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/ccd318/32.png) [@WardS\_Marcus\_D](https://www.ruby-forum.com/u/WardS_Marcus_D)\ **Post date:** [July 15, 2014, 7:22pm UTC](https://www.ruby-forum.com/t/why-am-i-dropping-data-over-the-udp-network/230908/10 "2014-07-15T19:22:19Z")
Ok so now I went to try out my architecture this time with a TCP source and sink. I have pictures included where the sending side is (TCPrecievestation) and the receiving side is (TCPreceivedisplaystation). On the (TCPreceievestation), the last three lines in the bottom window is as follows: RuntimeError: LookupError: KeyError: No devices found for --------\> Device Address: Addr: (My USRP’s IP address) On the (TCPreceievedisplaystation), all I am getting is this: using volk machine: avx\_64\_mmx\_orc To add, I have scopes for both the sending and receiving end, but as I run them, the plots do not show. Is there something that I could be missing since I am dealing with TCP and not UDP? ---
**Author:** ![WardS\_Marcus\_D](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/ccd318/32.png) [@WardS\_Marcus\_D](https://www.ruby-forum.com/u/WardS_Marcus_D)\ **Post date:** [July 15, 2014, 7:59pm UTC](https://www.ruby-forum.com/t/why-am-i-dropping-data-over-the-udp-network/230908/11 "2014-07-15T19:59:59Z")
On the machine that has the USRP connected (presumable this is a N2xx or USRP2?), what does: ping 192.168.10.2 return? Ping 192.168.10.2 is returning data what does uhd\_usrp\_probe --args “addr=192.168.10.2” Return? This returns an error message: RuntimeError: LookupError: KeyError: No devices found for --------\> > Device Address: > Addr: (192.168.10.2) ---
**Author:** ![WardS\_Marcus\_D](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/ccd318/32.png) [@WardS\_Marcus\_D](https://www.ruby-forum.com/u/WardS_Marcus_D)\ **Post date:** [July 15, 2014, 7:36pm UTC](https://www.ruby-forum.com/t/why-am-i-dropping-data-over-the-udp-network/230908/12 "2014-07-15T19:36:05Z")
On 07/15/2014 01:21 PM, Ward, Marcus D. wrote: > To add, I have scopes for both the sending and receiving end, but as I run them, > the plots do not show. > > Is there something that I could be missing since I am dealing with TCP and not > UDP? One thing I noticed immediately is that you have the sample rate set to 32k, which is not a valid sample rate for ANY USRP hardware. On the machine that has the USRP connected (presumable this is a N2xx or USRP2?), what does: ping 192.168.10.2 return? what does uhd\_usrp\_probe --args “addr=192.168.10.2” Return? ---
**Author:** ![WardS\_Marcus\_D](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/ccd318/32.png) [@WardS\_Marcus\_D](https://www.ruby-forum.com/u/WardS_Marcus_D)\ **Post date:** [July 15, 2014, 8:09pm UTC](https://www.ruby-forum.com/t/why-am-i-dropping-data-over-the-udp-network/230908/13 "2014-07-15T20:09:32Z")
On 07/15/2014 01:57 PM, Ward, Marcus D. wrote: > Return? > > This returns an error message: > RuntimeError: LookupError: KeyError: No devices found for --------\> > > > Device Address: > > Addr: (192.168.10.2) > > And the firmware in the device matches the UHD you have? Assuming that there’s nothing _else_ on the network connection between the host computer and the USRP device, that’s the only thing I can think of that might cause it to be pingable, but UHD can’t communicate with it, unless you have firewall rules preventing communications at the UHD layer… ---
**Author:** ![WardS\_Marcus\_D](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/ccd318/32.png) [@WardS\_Marcus\_D](https://www.ruby-forum.com/u/WardS_Marcus_D)\ **Post date:** [July 15, 2014, 9:03pm UTC](https://www.ruby-forum.com/t/why-am-i-dropping-data-over-the-udp-network/230908/14 "2014-07-15T21:03:15Z")
On 07/15/2014 02:58 PM, Ward, Marcus D. wrote: > And the firmware in the device matches the UHD you have? Based on my structure, > the firmware should be matching (since when I did the flow graph with the UDP, > everything went fine except for data loss) and correct me if I’m wrong, but an > error would come on saying that the firmware is not compatible? > A very-old firmware/FPGA image with a modern UHD may yield a “I can’t > find the device” error, such as you’ve seen. ---
**Author:** ![WardS\_Marcus\_D](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/ccd318/32.png) [@WardS\_Marcus\_D](https://www.ruby-forum.com/u/WardS_Marcus_D)\ **Post date:** [July 16, 2014, 7:48pm UTC](https://www.ruby-forum.com/t/why-am-i-dropping-data-over-the-udp-network/230908/15 "2014-07-16T19:48:14Z")
I don’t think it’s a firewall rule problem, but do you think opening up ports would solve my problem? I know the port I’m currently using on the TCP connection is port#: 1234 which deals with Mercurial and git default ports for serving Hyper Text. When I had the UDP connection, I was using the same port (1234) except that in UDP, that port deals with a VLC media player. ---
**Author:** ![WardS\_Marcus\_D](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/ccd318/32.png) [@WardS\_Marcus\_D](https://www.ruby-forum.com/u/WardS_Marcus_D)\ **Post date:** [July 16, 2014, 7:59pm UTC](https://www.ruby-forum.com/t/why-am-i-dropping-data-over-the-udp-network/230908/16 "2014-07-16T19:59:16Z")
Marcus, What OS are you using? I had the same issue (UDP not getting through on receive side) with Fedora 20, even with Firewall “supposedly” turned off (i.e. Trusted Zone selected). Manually adding the port exemption (I believe I used port 65000) let the UDP through and it worked. Lou KD4HSO Ward, Marcus D. wrote > I don’t think it’s a firewall rule problem, but do you think opening up > ports would solve my problem? I know the port I’m currently using on the > TCP connection is port#: 1234 which deals with Mercurial and git default > ports for serving Hyper Text. > > When I had the UDP connection, I was using the same port (1234) except > that in UDP, that port deals with a VLC media player. – View this message in context: [http://gnuradio.4.n7.nabble.com/Why-am-I-dropping-data-over-the-UDP-network-tp49283p49387.html](http://gnuradio.4.n7.nabble.com/Why-am-I-dropping-data-over-the-UDP-network-tp49283p49387.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![WardS\_Marcus\_D](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/ccd318/32.png) [@WardS\_Marcus\_D](https://www.ruby-forum.com/u/WardS_Marcus_D)\ **Post date:** [July 17, 2014, 1:13pm UTC](https://www.ruby-forum.com/t/why-am-i-dropping-data-over-the-udp-network/230908/17 "2014-07-17T13:13:58Z")
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**Author:** ![WardS\_Marcus\_D](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/ccd318/32.png) [@WardS\_Marcus\_D](https://www.ruby-forum.com/u/WardS_Marcus_D)\ **Post date:** [July 15, 2014, 8:59pm UTC](https://www.ruby-forum.com/t/why-am-i-dropping-data-over-the-udp-network/230908/18 "2014-07-15T20:59:40Z")
And the firmware in the device matches the UHD you have? Based on my structure, the firmware should be matching (since when I did the flow graph with the UDP, everything went fine except for data loss) and correct me if I’m wrong, but an error would come on saying that the firmware is not compatible? Assuming that there’s nothing _else_ on the network connection between the host computer and the USRP device, that’s the only thing I can think of that might cause it to be pingable, but UHD can’t communicate with it, unless you have firewall rules preventing communications at the UHD layer… I’ll dig into it more to see what else I can come up with. Thank You, Marcus ---
**Author:** ![WardS\_Marcus\_D](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/ccd318/32.png) [@WardS\_Marcus\_D](https://www.ruby-forum.com/u/WardS_Marcus_D)\ **Post date:** [July 17, 2014, 3:16pm UTC](https://www.ruby-forum.com/t/why-am-i-dropping-data-over-the-udp-network/230908/19 "2014-07-17T15:16:37Z")
Take a look at netstat -s and see if that helps isolate if or where packet loss is occurring. For example in the udp: section there are statistics for total datagrams tx/rx along with dropped, bad checksums, etc. UDP has no retransmission feature built in so bad checksums and bad packets get dropped. Any sort of retransmission of dropped packets must be in the software. [Brad H.] ---
**Author:** ![WardS\_Marcus\_D](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/ccd318/32.png) [@WardS\_Marcus\_D](https://www.ruby-forum.com/u/WardS_Marcus_D)\ **Post date:** [July 17, 2014, 2:53pm UTC](https://www.ruby-forum.com/t/why-am-i-dropping-data-over-the-udp-network/230908/20 "2014-07-17T14:53:47Z")
It is my understanding that the UDP protocol does not quarentee delivery to the destination. That is, it has no recovery mechanism for undelivered packets. Alan From: [discuss-gnuradio-bounces+alan.r.hill=removed\_email\_address@domain.invalid](mailto:discuss-gnuradio-bounces+alan.r.hill=removed_email_address@domain.invalid) [[mailto:discuss-gnuradio-bounces+alan.r.hill=removed\_email\_address@domain.invalid](mailto:discuss-gnuradio-bounces+alan.r.hill=removed_email_address@domain.invalid)] On Behalf Of Marcus L. Sent: Wednesday, July 16, 2014 11:09 AM To: [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) Cc: [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) Subject: Re: [Discuss-gnuradio] Why am I dropping data over the UDP network? I’m talking about the UDP traffic between the host and the N2xx device. on Jul 16, 2014, madengr [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: Marcus, What OS are you using? I had the same issue (UDP not getting through on receive side) with Fedora 20, even with Firewall “supposedly” turned off (i.e. Trusted Zone selected). Manually adding the port exemption (I believe I used port 65000) let the UDP through and it worked. Lou KD4HSO Ward, Marcus D. wrote > I don’t think it’s a firewall rule problem, but do you think opening up > ports would solve my problem? I know the port I’m currently using on the > TCP connection is port#: 1234 which deals with Mercurial and git default > ports for serving Hyper Text. > > When I had the UDP connection, I was using the same port (1234) except > that in UDP, that port deals with a VLC media player. – View this message in context: [http://gnuradio.4.n7.nabble.com/Why-am-I-dropping-data-over-the-UDP-network-tp49283p49387.html](http://gnuradio.4.n7.nabble.com/Why-am-I-dropping-data-over-the-UDP-network-tp49283p49387.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). [Next page](https://www.ruby-forum.com/t/why-am-i-dropping-data-over-the-udp-network/230908.md?page=2)