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IP dropout? Mailserver disconnect?

Discussion in 'Networking' started by stretchr, Jan 30, 2002.

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  1. stretchr

    stretchr Thread Starter

    Joined:
    Apr 1, 2001
    Messages:
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    Hi guys,

    Got a problem here that is causing real disruptions to our business, and hoping someone here can shed some light.

    Situation:
    TCP/IP network of approx 25 machines, 1 NT4 server as firewall, 1 Linux server (RH 7.1?) doing qmail, courier-IMAP, DHCP, DNS etc.
    We recently hooked up to an ADSL connection, for which we had to dump our old CISCO router, we were provided with a Netgear Router/Firewall which we couldn't get configured quite as we wanted.
    Instead we installed a second ethernet card in the Linux box which connected directly to the ADSL modem, so the Linux box is now doing routing, firewalling and NAT.
    This seemed to be about when our problems started.
    As our browser and email client, we use Netscape (4.76+). We connect to the mail server using IMAP. Every so often, we find ourselves unable to connect to the mail server, and at the same time, also find ourselves unable to connect to the internet, even with Internet Explorer.
    We use a proxy server for http and security, all machines have their browsers configured to use it - without a proxy we can't connect.
    The thing is, each machine goes down at different times, never are they all down at the same time.

    So, does anyone have the slightest inkling of an idea about what might be going on?

    Rich
     
  2. Rockn

    Rockn

    Joined:
    Jul 29, 2001
    Messages:
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    I would look at the DHCP setup and see when the leases for the IP addresses expire. Did your ISP give you static IP's for your External address and internal ones? If they are using DHCP also that could be causing the problem or part of it.
     
  3. stretchr

    stretchr Thread Starter

    Joined:
    Apr 1, 2001
    Messages:
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    We have static IP for external, internal are of the format 192.168.1.x
    Just now when my mail dropped out again - just for a couple of minutes this time - I tried pinging the internal address of the mailserver (192.168.1.1) with no response, yet I could ping other machines on the network.
    Sometimes it seems like the connection to the mailserver drops out for just a few minutes, other times for much longer (.5 hour or 1 hour or more).
     
  4. stretchr

    stretchr Thread Starter

    Joined:
    Apr 1, 2001
    Messages:
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    C'mon guys, surely someone must have some ideas!!
    What on earth could it be that lets me connect to the mail server for 5 minutes, then not for 5 minutes, then on again for 5 minutes, then off again for 5 minutes .. etc etc .... and for everyone else on our network, at different times and for different periods??
     
  5. English Guy

    English Guy

    Joined:
    Nov 18, 1999
    Messages:
    133
    sounds to me like your linux box is causing all the problems, probably creating some kind of broadcast storm on the network. Have you thought of replacing this with a Linksys Router?
    Or set up the Linux box on its own network, so that it is not on the same network as the rest of the LAN?
     
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