Selecting Active Site in VSLS

Overview of VSLS

In the Traditional VSX mode, you can configure the Security Group to work in the Virtual System Load Sharing (VSLS) mode - see set cluster configuration high-availability.

In the VSLS mode, each Virtual System works as an independent cluster:

  • One Site is Active for this Virtual System.

  • One Site is Standby for this Virtual System.

Algorithm to Select an Active Site in VSLS

For each Virtual System independently, the VSLS mode selects the Active Site based on criteria in this order of priority:

  1. Availability of functional interfaces for the Virtual System:

    The VSLS mode selects the Site with the most connected interfaces to be the Active Site.

  2. Availability of the Security Group Members in the state "UP":

    If both Sites have the same number of connected interfaces, the VSLS mode uses this algorithm to select the Active Site:

    1. On each Site, get the number of the Security Group Members in the state "UP".

    2. Calculate the ratio:

      Ratio = [(the smaller number) / (the larger number)] x 100%

    3. Select the Active Site based on the Ratio and the Threshold values:

      • If Ratio < Threshold, then select the Site with the most available Security Group Members to be the Active Site.

      • If Ratio >= Threshold, then skip to the next criterion.

    The default threshold value is 50%.

    The threshold determines the minimum required number of the Security Group Members in the state "UP" on a Site.

    If the ratio decreases below this threshold, then the VSLS mode performs the failover to the other Site.

    Example:

    1. Site 1 has two Security Group Members in the state "UP".

    2. Site 2 has five Security Group Members in the state "UP".

    3. Ratio = (2 / 5) x 100% = 40%

    4. The ratio of 40% is lower than the default threshold of 50%.

    5. The VSLS mode selects Site 2 as the Active Site.

    You can control the threshold value with the kernel parameter "fwha_mbs_vsls_chassis_sgm_ratio":

    1. Connect to the command line on the Security Group.

    2. Get the current value:

      • In Gaia gClish:

        fw ctl get int fwha_mbs_vsls_chassis_sgm_ratio

      • In the Expert mode:

        g_allc fw ctl get int fwha_mbs_vsls_chassis_sgm_ratio

    3. Configure the desired threshold value:

      • In Gaia gClish:

        update_conf_file fwkern.conf fwha_mbs_vsls_chassis_sgm_ratio=<Value>

      • In the Expert mode:

        g_update_conf_file fwkern.conf fwha_mbs_vsls_chassis_sgm_ratio=<Value>

  3. Virtual System reports a problem

    When a Virtual System fails on the Active Site, the VSLS mode automatically performs the failover to the other Site, which becomes the new Active Site for this Virtual System.

  4. Primary Site

    If none of the above criteria causes the VSLS mode to select an Active Site, the Primary Site automatically becomes the Active Site.

    To configure the Primary Site and the Secondary Site, see set cluster configuration high-availability.