Configuring GSLB protocol parameters | 1 |
For each VIP of interest, the GSLB ServerIron ADX stores the number of active bindings for the respective application port.
If the agent is running a software image that does not support the active bindings metric, it does not report any information specific to the active bindings metric. In this case, the default active bindings value for each VIP residing on that site is 1 or 0, depending on the health status of the VIP. If the VIP is active, the value is 1. If the VIP is not active, it is 0.
By default, the active bindings metric is disabled. When enabled, it is placed after the
DNS response processing
When the active bindings metric is enabled, the GSLB ServerIron ADX evaluates each IP address in the DNS reply from the server, and selects the IP address with the highest number of active bindings. The client subsequently makes an SLB request to that IP address.
Active bindings are calculated as follows:
•If the IP address is a VIP residing on a remote site that supports active bindings, then the number of active bindings equals the number of active real servers bound for application ports.
•If the IP address is a VIP residing on a remote site that is running older versions of the GSLB agent software, and consequently does not support the active bindings metric, then the number of active bindings for the IP address is 1 or 0, depending on the health of the VIP.
•If the IP address is a real server, then the number of active bindings for the IP address is 1 or 0, depending on the health of the real server.
If all IPs or VIPs have zero active bindings, or if all IPs or VIPs have the same number of active bindings, the GSLB ServerIron ADX passes them on to the next step in the GSLB algorithm, where the process of selecting the best IP address continues. Likewise, if two or more IP addresses have the highest maximum value of active bindings, the GSLB ServerIron ADX passes them on to the next step in the GSLB algorithm.
Enabling active bindings
Active bindings are a measure of the number of active real servers bound to a Virtual IP address (VIP) residing on a GSLB site. The GSLB ServerIron ADX uses the active bindings metric to select the best IP address for the client. The VIP with the highest number of active bindings is the IP address preferred by the active bindings metric.
To configure the active bindings metric, enter the following command.
Syntax: [no]
Displaying active binding information
To view active bindings for each IP address, enter the following command.
ServerIronADX# show gslb dns detail
Syntax: show gslb dns zone
Refer to “Displaying the results of traffic distribution for Weighted IPs” on page 42 for an example screen display.
ServerIron ADX Global Server Load Balancing Guide | 47 |
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