On 09/28/2015 05:14 AM, David Halls wrote:
Thanks for your reply Marcus, but does that mean there is no way
around the problem?
Regards,
David
Naked UDP provides no framing overlay, which means you are limited to
MTU-sized packets.
You should perhaps look into either using TCP, and/or ZMQ.
Others can provide guidance on ZMQ usage.
------------------------------------------------------------------------
*From:* mle...@ripnet.com <mle...@ripnet.com>
*Sent:* 25 September 2015 20:24
*To:* Andy Walls
*Cc:* David Halls; discuss-gnuradio@gnu.org;
discuss-gnuradio-bounces+mleech=ripnet....@gnu.org
*Subject:* Re: [Discuss-gnuradio] UDP Sink Size Limit - ERROR: send
error:send_to: Message too long
If the sending machine sets DF in the IP header, then any interstitial
machine that must fragment will drop the packet as well.
Best to stick to MTU-sized payloads with UDP, since IP fragmentation
is handled poorly in many cases--either due to policy, or bad
implementations.
On 2015-09-25 15:17, Andy Walls wrote:
From: David Halls Subject: [Discuss-gnuradio] UDP Sink Size Limit -
ERROR: send
error:send_to: Message too long
Date: Fri, 25 Sep 2015 09:05:56 +0000
Dear All, When I increase my packet length in a transmission flow
graph to over 16,000 bits, I get the following error "ERROR: send
error:send_to: Message too long"
This looks like the underlying sendto() system call is returning
EMSGSIZE. From man sendto:
EMSGSIZE
The socket type requires that message be sent atomically, and
the size of the message to be sent made this impossible.
this is from the UDP block which I am using in order to send the
transmitted bits to the destination in order to perform BER. I am
sending the packets in bursts, one packet every two seconds.
I currently have the Payload size set to 147.2k and Send Null Pkt as
EOF set to true.
Is this some fundamental limit, or can I overcome the issue?
16,000 bits is 2000 bytes. The default MTU is usually 1500 bytes (for
IP header, UDP header, and payload together). Try modifying the MTU on
your machine's network interface to something larger, say 4000.
The MTU of the receiving machine or other network hardware might still
be only 1500, so the the UDP packet could get IP fragmented. I'm not
sure how well UDP works when fragmented.
-Andy
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