WLan Roaming & System.Data.SqlClient

[Axel Stallknecht]

Hi folks,

we use in our stock 15 Cisco 1230 access points with Intermec 700 barcode
scanners.
My C# application runs on the Intermecs. It builds a
System.Data.SqlClient.SqlConnection
to a MSSQL server. Most of the time, the scanners are associated to just one
access point.
But sometimes roaming occurs. If this happens the SQL server connection get
lost.
I haven't really found a solution for this problem. Does anyone out there
have a solution for
such a situation ?

Thanks in advance & best regards
Axel

 

[Paul G. Tobey [eMVP]]

Hmmm. The connection should be persistent unless the network infrastructure
(the stuff beyond the access point), is breaking it. You aren't, by any
chance, assigned a new IP address or one in a different subnet when you
"roam", are you? Obviously, if your IP address changes, a TCP connection
*can't* persist...

Paul T.

 

[Axel Stallknecht]

Well, the IP adress doesn't change, because they are static. In the
beginning of the project
I often got problems with DHCP on these PPC devices. Other (stateless)
applications like
Pocket IE never had problems with roaming.
I also tried a ftp session from the device to a network server while I moved
from the first access point
to the last one without any trouble, without retries or reconnects. On the
log of the AP's I can see that the device
is roamed from one AP to the next. I seems the only problem occurs with
System.Data.SqlClient.SqlConnection.
If a worker is just assigned to one AP I never lose the connection to the
sql server. But if roaming
occurs, sometimes (not every time !!!) the connection get lost. It's also
very hard to reproduce.
Very strange !!!

cu
Axel

 

[Rüdiger Kardel]

Hi Axel,

sounds to me like a problem in your network infrastructure. A connection
should survive roaming.

But where's the problem?
An application, designed for PPCs should handle the loss of connection
anyway. When the device is switched off you will run into the same
situation: connection lost. You have to reconnect automatically within your
program code.

regards
Ruediger