ISP do not provide more then 1 public ip...



  • Hello Guys,

    i want use CARP with 2x ISP but both are dont provide more then 1 public ip. I have a way to make it possible?

    best regards René



  • Hello René,

    If you want to use CARP you need 3 IP addresses in the same subnet/broadcast domain.

    One is your MASTER IP, one is your BACKUP IP and one is your shared IP. So you need a /29 as a minimum. ISP handing out /30 or spoofed /32 addresses won't really work.

    Please read vorkbaard's excellent walkthrough on setting up HA and CARP.

    You can set up failover with two ISP lines each with its own IP address. However, in case of a fail-over/failure, your internal clients will use a different outside IP address.

    Practical approach;
    Have your ISP modem hand-out private IP, setup CARP and have the modem forward all data (DMZ host) to your shared IP address. Poormans solution, but does work.

    Best would be to have two separate ISP internet connections (with separate physical cable paths) and have them delivered with a /30 subnet.

    Regards
    Niels


  • LAYER 8 Netgate

    Best would be to have two separate ISP internet connections (with separate physical cable paths) and have them delivered with a /30 subnet.

    I think you mean /29.



  • Correct
    /30 is only good for point to point.
    /29 makes live certainly more easier when carp is required.
    Niels



  • Hello Niels,

    thanks for the help, i cant change my ISP. How can i forward my data to the private ip of the Modem?

    best regards René



  • René,

    Depends on your modem. You can. Ask your isp for the instructions. But to you can try to log on to the modem and look for DMZ host or forwarding host and have it send all the data to your internal private specific IP address.

    Niels


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