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Re: Connection question

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----- Original Message ----- From: "Craig Ringer" <craig@xxxxxxxxxxxxxxxxxxxxx>
To: "Bayless Kirtley" <bkirt@xxxxxxx>
Cc: "List, Postgres" <pgsql-general@xxxxxxxxxxxxxx>
Sent: Thursday, September 02, 2010 10:15 PM
Subject: Re:  Connection question


On 2/09/2010 11:59 PM, Bayless Kirtley wrote:
Thanks a lot Craig. The register is connecting through localhost so it's
not that. I
guess I'm not surprised about the Windows thing. I suppose we'll just
have to
live with it then.

I wouldn't be too sure yet.

Did you run the test where you reboot the POS system with the ethernet unplugged? Does it still connect to the database OK?

I didn't think XP broke TCP/IP connections to *localhost* when an ethernet interface went up or down, unless the connection was to a local IP associated with that interface. If you're connected to 127.0.0.1 from 127.0.0.1 it shouldn't, AFAIK, matter if you lose your wifi/ethernet.

Come to think of it, you might want to check to make sure the local Ethernet interface is set to use DHCP. If it's using a static IP, Windows might permit that IP to be used to talk to the local host even when there's no link on the interface. So - to be sure, you can disable the Ethernet interface in the network control panel before your reboot for testing.


Anyway, if you really can't make it work properly, there's a simple if mildly clumsy workaround. You can prevent XP from realizing it's lost its connection to the router by placing another device between the XP machine(s) and the router, like a plain old cheap switch. That way Ethernet link on the XP machines is never lost when you reboot the router - only between the router and the switch, where the XP machines can't tell. When the router goes down they lose their DHCP server, but that doesn't matter if it comes up again before they try to renew their DHCP leases, and for local-to-local traffic that's about all they'll be relying on the router for. You could even avoid that by setting static IP addresses.

--
Craig Ringer

Tech-related writing at http://soapyfrogs.blogspot.com/

Hmmm, more to consider then. I have not done the test you suggested.
Guess I pounced on the Windows losing TCP/IP prematurely. It has
been a while but I think I set them up for static IP addresses initially. I
did check to be certain it is using localhost though. I will catch a slow
day soon and try your ideas. I'll report the results back soon.

Thanks Craig,
Bayless



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