[jdev] Re: XMPP Ping method?

Bruce Campbell list-jdev at vicious.dropbear.id.au
Thu Nov 2 04:20:16 CST 2006

On Wed, 1 Nov 2006, Tomasz Sterna wrote:

> On 11/1/06, Alexander Gnauck <gnauck at ag-software.de> wrote:
>> for some devices it's not. If you work with wireless devices (WLAN, GSM,
>> UMTS) you will see lot's of strange behavior.
> Isn't that broken TCP implementation then?

No; it reflects the design of TCP being based around reliable connections 
where interruptions were infrequent and short in duration (or permanently 

With the advent of new underlying medias which suffer from frequent 
interruptions of highly variable durations, the default TCP values do not 
cope as well.

I'd imagine that certain embedded wireless devices tightly couple the TCP 
retransmission to the underlying carrier detection.  However, many 
devices, for example my laptop, do not have such a tight coupling (if at 
all) and must rely on the TCP retransmission coinciding with the wireless 
card having a reliable signal to the base station.

You can change the client, but asking the server to do so is not the 

   Bruce Campbell.

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