RE: [load balancing] active-active mode, each controller balancin g the same virtual servers?

From: Rick Masters (
Date: Fri Jan 11 2002 - 16:37:54 EST

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    You can make servers available to both big-ips in an
    active-active scenario.

    Typically it is not setup this way because BIG-IP is
    commonly deployed as the default route and if you have
    two big-ips running at the same time, the packets need
    to go back to the right one, and the most straightforward
    way to do that is to provision the servers among the big-ips
    and set each server's default route to the proper big-ip.

    However, there is an alternate scheme. You can configure
    all connections to go through a SNAT and that way the
    return address will be changed to a big-ip address so
    the packets will go back to the proper big-ip.
    Many customers don't like SNAT because you lose the original
    client ip address. With version 4.2 (available next month;
    or you can try to get in the beta program and get it this month),
    big-ip can insert an http header to preserve the original client
    ip address, and so you can use that header in your logs.

    As far as the virtual servers, as stated in another message,
    those can only be active on one big-ip at a time. If one big-ip
    fails, the remaining unit will pick up both sets of virtual

    hope that helps,

    Rick Masters
    F5 Networks

    -----Original Message-----
    From: Stephen Worotynec []
    Sent: Friday, January 11, 2002 8:34 AM
    Subject: [load balancing] active-active mode, each controller balancing
    the same virtual servers?


    With two load balancers in active-active mode, could each controller
    balance the same pool of web servers?

    For example, I see a brief mention in Tony Bourke's book "Server Load
    Balancing", pp. 18-19: "both VIPS answer on both load balancers, with a
    protocol circumventing the restriction that two load balancers may not
    hold the same IP address".

    I'm wondering what brands of load balancer support this scenario, and in
    particular if it is possible on F5 BIG-IPs?

    Thanks in advance.


    Stephen Worotynec

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