[En-Nut-Discussion] RE: ARP packets crashing the TCP stack

[Don Ingram]

Harald,

Thanks for the reply, I will disable the watchdog & see if it hangs the task 
instead, judging by your comments it is probably stuck waiting to send the data.

Very busy so it may be a few more days before I get to try it.


Cheers

Don

  Kipp wrote:
> Hi,
> 
> While reading several messages in this list, I'd like to make a
> general comment first. I'd recommend to use specific terms in order
> to avoid confusion.
> 
> Crash:
> http://en.wikipedia.org/wiki/Crash_%28computing%29
> This may include watchdog resets.
> 
> However, if it's known, that the system reboots due to a watchdog
> timeout, this should be clearly stated. In most cases the reset
> is then caused by not returning from a specific function call and
> it should be easy to locate this.
> 
> Now to Don's post:
> 
> At 09:28 20.06.2006 +1000, you wrote:
> 
>> An observation
>>
>> ( caution - I --USE-- NutOS but know bugger all --ABOUT-- NutOS ;-)
> 
> We are all experimenting in the dark. :-)
> 
> 
>> If a telnet connection is interrupted ( remove network cable )with 
>> data still in the stream allocated to the telnet port then the device 
>> will crash.
> 
> That makes me wonder. If you remove a network cable, the telnet
> connection will last forever on the receiver side. That's how
> TCP works. It may be avoided by keep alive packets (not supported
> by Nut/OS) or timeouts (supported by Nut/OS).
> 
> There had been discussions about informing the application about
> link loss. In real world applications this will be typically useful,
> but as I pointed out several times here several times, this is
> contrary to the philosophy behind TCP. Portable applications
> should be able to handle link losses without being notified.
> 
> The sender will receive an error after some time. This time is
> not configurable, btw.
> 
> Anyway, under no circumstances the TCP stack should crash, if
> the connection is terminated with not all buffered data sent
> out.
> 
> 
>> Could the SYSLOG message be intermittently failing & not be handled?
> 
> Syslog is based on UDP. The packet will silently evaporate.
> 
> Regards,
> Harald
> 
> _______________________________________________
> En-Nut-Discussion mailing list
> En-Nut-Discussion at egnite.de
> http://www.egnite.de/mailman/listinfo.cgi/en-nut-discussion
> 


-- 
Cheers

Don Ingram


Leading Edge Design

Mob:   +61 4 1877 5670
Ph :   +61 7 4942 5670
SIP: 899 060 4942 5670

Fax:   +61 7 4942 5680

23 Daniel St
North Mackay
QLD 4740
Australia

P.O. Box 10326
Mt Pleasant
QLD 4740
Australia