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From: | Bill Auerbach |
Subject: | RE: [lwip-users] TCP Disconnect Detection lwIP V1.2 |
Date: | Mon, 30 Mar 2009 13:28:29 -0400 |
Some suggestions: 1)
Use 2 connections (ports) – one for the real connection
and one for the 15S ping. 2)
Use TCP_KEEPALIVEs, but you have to change the default TCP_KEEPALIVE
time on the other end since the default is a long time and it won’t notice
the lost connection. 3)
Use UDP and send a “ping” for checking the device. I use the latter using a 5S sending period with a UDP broadcast and
it works pretty well for the PC (Win32) app to see the lwIP devices come and
go. This ping also gives me the opportunity to send out the device’s
IP address in the payload so that the PC can make a connection (TCP) once it
sees the device. Bill From:
address@hidden
[mailto:address@hidden On Behalf
Of Gurpal Gill Hello, I'm wondering how to detect that a TCP connection has been
closed? Also, if a connection were to get disconnected via a power outage
(simulated by disconnecting the ethernet cable from the device)?
Currently I transmit a byte of data every 15secs of no activity and when I get
an error I close the connection. I need a better way since the application on
the other end has to process the byte that I'm sending which causes problems.
I'm using lwIP with the xilinx tools (S3ADSP1800A eval board). Just a note, I'm
using lwIP in non blocking mode so the read command either returns -1 or the
number of bytes read. Any help would be appreciated. Regards, Gurpal Gill |
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