UDP Source: Difference between revisions

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[[Category:Block Docs]]
This block listens for traffic on the specified UDP port and outputs the specified data type.  Note that the header setting and payload size should match on both the sender and receiver.  For a normal network, a payload size of 1472 (1500-28 for UDP headers) represents the max size for a standard UDP packet.  For jumbo frames, 8972 can be used (9000-28).  Be careful adjusting this parameter as you could inadvertently cause unnecessary packet fragmentation and reconstruction.<br><br>
Read stream from an UDP socket.  Can be used with [[UDP Sink]] from another flowgraph or just an external application.  
If you need the block to generate 0s (zeroes) when there is no UDP data, you can turn on the 'Src 0s If No Data' flag, however this is best paired with the [[UDP_Sink]] block.  If using a separate application, problems can arise if the sending application is not calling its send function with blocks matching payload size (the logic here can get a 'partial' packet after starting and not continue to produce zeros).<br><br>
NOTE:<br>
For best performance and to ensure UDP packets are not dropped, add the following lines to your <code>/etc/sysctl.conf</code> and reboot (the reboot is required).<br>
<pre>
net.core.rmem_default=26214400
net.core.rmem_max=104857600
net.core.wmem_default=65536
net.core.wmem_max=104857600
</pre>
IT IS HIGHLY RECOMMENDED that the example test_udp_source/sink flowgraphs be tested with the sequence number header enabled (the default in those flowgraphs) as a validation that no network or IP stack bottlenecks may cause dropped packets at the rates planned in your environment before using in production, especially if headers will not be used in your environment to track dropped packets.


== Parameters ==
== Parameters ==
; IP Address
<code>For the version with 4 params depreciated in 3.9, see [https://wiki.gnuradio.org/index.php?title=UDP_Source&oldid=8001 this page]</code>
: The name or IP address of the transmitting host; can be NULL, None, or "0.0.0.0" to allow reading from any interface on the host


; Port
; Port
: The port number on which to receive data; use 0 to have the system assign an unused port number
: Port number; default: 1234
 
; Header
: options: [None, 64-bit Sequence Number, Sequence + 16-bit data size, ATA Header]
 
; UDP Packet Data Size
: default: 1472


; Payload Size
; Notify Missed Frames
: UDP payload size by default set to 1472 = (1500 MTU - (8 byte UDP header) - (20 byte IP header))
: options: [No, Yes]


; Null Packet is EOF
; Src 0s If No Data
: Interpret zero-length packet as EOF (default: true)
: options: [No, Yes]
 
; Enable IPv6 Support
: options: [No, Yes]
 
; Vec Length
: vector length; default: 1


== Example Flowgraph ==
== Example Flowgraph ==
Line 34: Line 54:
; Block definition
; Block definition
: [https://github.com/gnuradio/gnuradio/blob/master/gr-network/grc/network_udp_source.block.yml 4]
: [https://github.com/gnuradio/gnuradio/blob/master/gr-network/grc/network_udp_source.block.yml 4]
[[Category:Block Docs]]

Latest revision as of 17:51, 11 February 2021

This block listens for traffic on the specified UDP port and outputs the specified data type. Note that the header setting and payload size should match on both the sender and receiver. For a normal network, a payload size of 1472 (1500-28 for UDP headers) represents the max size for a standard UDP packet. For jumbo frames, 8972 can be used (9000-28). Be careful adjusting this parameter as you could inadvertently cause unnecessary packet fragmentation and reconstruction.

If you need the block to generate 0s (zeroes) when there is no UDP data, you can turn on the 'Src 0s If No Data' flag, however this is best paired with the UDP_Sink block. If using a separate application, problems can arise if the sending application is not calling its send function with blocks matching payload size (the logic here can get a 'partial' packet after starting and not continue to produce zeros).

NOTE:
For best performance and to ensure UDP packets are not dropped, add the following lines to your /etc/sysctl.conf and reboot (the reboot is required).

net.core.rmem_default=26214400
net.core.rmem_max=104857600
net.core.wmem_default=65536
net.core.wmem_max=104857600

IT IS HIGHLY RECOMMENDED that the example test_udp_source/sink flowgraphs be tested with the sequence number header enabled (the default in those flowgraphs) as a validation that no network or IP stack bottlenecks may cause dropped packets at the rates planned in your environment before using in production, especially if headers will not be used in your environment to track dropped packets.

Parameters

For the version with 4 params depreciated in 3.9, see this page

Port
Port number; default: 1234
Header
options: [None, 64-bit Sequence Number, Sequence + 16-bit data size, ATA Header]
UDP Packet Data Size
default: 1472
Notify Missed Frames
options: [No, Yes]
Src 0s If No Data
options: [No, Yes]
Enable IPv6 Support
options: [No, Yes]
Vec Length
vector length; default: 1

Example Flowgraph

This flowgraph can be found at [1]

Test udp source fg.png

Source Files

C++ files
1
Header files
2
Public header files
3
Block definition
4
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