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  1. #1
    Join Date
    Oct 2003
    Location
    Singapore
    Posts
    317

    Configured a New NIC for a diff subnet - but not working

    We have two NICs on the server,
    eth0 is connected to a switch which routes the 209.120.239.xx IPs, and that eth1 is connected to a switch that routes the 216.66.21.xx IPs.

    Both switches handle the full 256 IPs on the subnet, so it's not a matter of routing.

    In fact, the only place the 216.66.21.xx IPs go is to that switch that our server is connected to.

    We can make either 209.120.239.xx or 216.66.21.xx IPs repond to ping but not both at the same time.

    What might be the issue??

    The server is on RH9 with cPanel v8.8.0.

    Thanks a lot!
    Cyber Ultra Network - Reliable Budget Web Hosting Provider Since 2003

  2. #2
    Join Date
    Feb 2004
    Location
    Louisville, Kentucky
    Posts
    1,083
    Are you able to ping both of your box's IP addresses from directly-connected hosts? For example, if you ask your ISP to ping your box from their router on "switch A" and again from "switch B" without any configuration changes in-between, does this work?

    If that works, it's possible that your ISP is filtering your traffic based on the source IP address in your outbound packets. ISPs will do this to prevent their customers from conducting DoS attacks with spoofed source IP addresses.

    Do you need to reach the "entire Internet" via both NICs? If not, you can add specific route statements to whichever NIC you use as a private use NIC.

    If you are using both as default gateways to the "entire Internet", you should ask your host(s) to allow those extra IP addresses in their filters.

    Alternatively, you could use Linux's iproute2 (assuming you run Linux!) to choose which NIC to use, based on which IP address is the source of the outbound packet. This is quite advanced, but you can read about it at http://lartc.org. There is a specific example of this type of source-based policy routing at http://www.linux.org/docs/ldp/howto/...db.simple.html however it assumes a certain familarity with iproute2.

    Your host may be able to help you out with this. If not, I suggest you hire a good sysadmin for a couple hours to set things up for you.

    Hope this helps.

    --
    Jeff at Reflected Networks

  3. #3
    Join Date
    Apr 2003
    Location
    Pittsburgh, Pa
    Posts
    200

    Re: Configured a New NIC for a diff subnet - but not working

    Originally posted by cyberultra
    We have two NICs on the server,
    eth0 is connected to a switch which routes the 209.120.239.xx IPs, and that eth1 is connected to a switch that routes the 216.66.21.xx IPs.

    Both switches handle the full 256 IPs on the subnet, so it's not a matter of routing.

    In fact, the only place the 216.66.21.xx IPs go is to that switch that our server is connected to.

    We can make either 209.120.239.xx or 216.66.21.xx IPs repond to ping but not both at the same time.

    What might be the issue??

    The server is on RH9 with cPanel v8.8.0.

    Thanks a lot!


    I am able to ping both at the same time. Please click on the link.

    http://www.g3tech.net/misc/ping.jpg

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