Routing problems

From: pcfixer (brad_at_co-opcu.net)
Date: 08/28/04

  • Next message: Tom Scales: "Re: Dell Servers On Ebay" 
    Date: Fri, 27 Aug 2004 17:05:15 -0500

    Okay, let's see if I can explain all this clearly, because it's fairly
    complicated. Where I work, we have a somewhat complicated network. Here in
    our main office (192.168.1.0), we have 3 gateways - one for Internet access,
    and two others that are frame relay WAN routers that connect us to our three
    branch offices. Our Internet gateway is a Linux firewall server running
    Slackware 8.1. This server is supposed to be the central router for all of
    our subnets. Routes to two of the branch offices (192.168.2.0, 192.168.3.0)
    get routed to a router that goes out onto Sprint frame relay, while the
    route to our newest branch (192.168.4.0) goes out on the other router, which
    is Qwest frame relay. Again, the Linux firewall server is supposed to be
    handling all the routing for the 4 subnets.

    Aside from our newest branch office, each location has its own Internet
    access. Our new branch has its Internet routed through our main office.
    The router in the remote location sends everything to the Qwest frame relay
    router in the main office. That router then sends packets bound for one of
    the other branches directly to the Sprint router, and everything else
    (0.0.0.0) to the Linux firewall. This way, it SHOULD be able to communicate
    with all the computers in the main office and also have Internet access to
    the remote branch.

    Now, here's the problem. At any given time, I can communicate with any of
    the computers in the remote branch over the Qwest line by pinging, shared
    folders, etc. However, the remote branch seems to have a problem
    communicating with the computers in our main office except for the ones that
    have a local static route for the .4 subnet manually programmed into them.
    In other words, for some reason, the Linux firewall is not forwarding
    incoming requests from the Qwest router to the appropriate computers in the
    main office. And here's the weird part. Every once in a while, it actually
    will work for a while, and then it will quit again. I've pretty much
    exempted the Qwest router from being the issue, because I changed the
    default gateway on one machine to a different server (which also has the
    routing table programmed into it for backup purposes), and then I could
    communicate with it just fine from the remote branch. Also, even when the
    packets are not being forwarded by the Linux firewall, I can still ping it
    at any time from the remote branch. And here's where it gets even weirder.
    Even when computers on the remote end can't communicate with computers down
    here, they can still get Internet access through the Linux firewall.

    There's only two things I can think of at this point. Either the Qwest
    router in the main office needs a static route programmed into it for the
    192.168.1.0 subnet with the gateway IP set as the router's eth0 IP,
    (doubtful), or something is goofy in the Linux firewall setup. If you're
    totally by now, I don't blame you. It's taken me several weeks to get this
    all into my head and sorted out. If anybody has any suggestions on how to
    further isolate the problem and/or how to fix it, please let me know ASAP.
    Thanks.

  • Next message: Tom Scales: "Re: Dell Servers On Ebay"

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