What Angus do is an approach, but indeed as he claim, it can get a
expencieve, specially when the vehicles are in other countries.
You also have to be aware that another vehicle can connect with an IP
address of a 'loosed' vehicle, so then you have on your server 3
connections with same IP. Even worse, with most providers you can send
data to both of them without getting an error !! If you send data, then
the 'loose' one will disconnect... after... 5 minutes ... soemtime 30
minutes, depending on provider (most do it in 5 minutes). Even worse,
some providers do NAT, so then every vehicle has same IP address.
How I like this kind of problems :)
What I mostly do is design a protocol layer with a logon, and timed
keep-alive packets (witch cost money). I base on the logon where each
vehicle has his exclusive logon (eg the serial number of SIM card). When
a vehicle logs on, and it is already logged on, then the old one is
loose and I disconnect it.
Wednesday, June 29, 2005, 20:03, Info 2004 wrote:
> I have some vehicles with GPRS modems connected to O2 in the UK. The
> problem I have is when the O2 "network" drops a connection to my server
> - i.e. a close not initiated from the vehicle, or my server. When this
> happens, I never see a disconnect, so the next time the unit reports in,
> it usually has a different IP address, and I still have the previous
> connection open, so I get a bit confused.
> Does anyone else see the same issue? If so, how did you get around it?
> I have based my server on SrvDemo.
> All help appreciated.
> ASA Micros Ltd.
> 141 Wardle Road,
> OL12 9JA
> Tel: +44(0)1706 355057
> Company No. 4722262
> VAT No. 704044772
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