[linrad] Re: MAP65 Beta Testing

[Pierre Vanhoucke <skynet.be; pierre.vanhoucke@xxxxxxxxxxxxxxxx>]

Hi Joe,

I am not an expert in networking either but enlarging  the packet buffersize 
could solve your problem:
After Leif increased the packet buffersize in the window version of watzo  
(win-wtz01-01) ,  I got rid of  a lost packet problem that was present in 
win-wtz01-00.

This change was based on the recommendation of Dirk Claessens who wrote:

********************************************************
I heard from Pierre that Linrad for Windows is experiencing sporadic 
packet loss. It appears that there exists no magic registry key to 
enlarge the packet buffersize on a global basis.

However, the buffersize can be set on a per socket basis:

To get the current size:
int skt, int sndsize;
err = setsockopt(skt, SOL_SOCKET, SO_RCVBUF, (char *)&sndsize, 
              ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ(int)sizeof(sndsize));


To set the new size:
int  Âsockbufsize = 0;
int  Âsize = sizeof(int);

err = getsockopt(skt, SOL_SOCKET, SO_RCVBUF, (char *)&sockbufsize, &size);

( to set the send buffer size: use SO_SNDBUF )


A word of caution: enlarging the buffer is not a magical solution. If - 
for whatever reason - a client cannot cope with the datarate of the 
server, the input buffers will overflow anyway, it will just take some 
more time. It will only help to cure occasional overload.
******************************************************

From what you describe, it looks  indeed that the bottleneck is not related to 
the speed  of your network connection but rather to the processing of the 
incoming packets.

   
Hope it helps

73,

Pierre/ON5GN



 
On Friday 06 July 2007 14:55, Joe Taylor wrote:

> I am anything but an expert in networking; in fact, I have
> some network-related questions of my own, as you will see below.

> For reasons I have not yet identified, my system works
> better with the network speed set at 10 Mb/s.  If I set it
> to 100 Mb/s things still work, but the percentage of dropped
> packets increases to about 2.6% in steady state.  Moreover,
> these numbers stay essentially the same (0.6% lost data at
> 10 Mb/s, 2.6% lost data at 100 Mb/s) if I disconnect both
> computers from the network hub and simply connect the two
> through a "crossover" cable.  Probably I am doing something
> stupid in the "recvpkt()" routine in MAP65; or perhaps I
> need to set some parameter differently in the Linux and/or
> Windows computers.  If anyone can shed light on the
> situation, or suggest some suitable diagnostics, I would be
> grateful.
>
> I use a completely different pair of computers for
> development work.  One runs Debian Linux (installed from
> Knoppix) and the other runs Win XP/Pro.  Between these
> machines the number of dropped packets is smaller but still
> not necessarily zero.  With the network supposedly running
> at 100 Mb/s, I fairly often see a few (0-20, say) dropped
> packets (out of a total 33103) in a minute.
>
> Loss of 1% of the data is arguably not very important.  It
> does not degrade JT65 decoding noticeably.  Nevertheless, i
> would like to understand what I am doing wrong.

#############################################################
This message is sent to you because you are subscribed to
  the mailing list <linrad@xxxxxxxxxxxxxxxxxxxxx>.
To unsubscribe, E-mail to: <linrad-off@xxxxxxxxxxxxxxxxxxxxx>
To switch to the DIGEST mode, E-mail to <linrad-digest@xxxxxxxxxxxxxxxxxxxxx>
To switch to the INDEX mode, E-mail to <linrad-index@xxxxxxxxxxxxxxxxxxxxx>
Send administrative queries to  <linrad-request@xxxxxxxxxxxxxxxxxxxxx>


LINRADDARNIL