Brocade Virtual ADX Global Server Load Balancing Guide (Supporting ADX v03.1.00) - Manual (Page 160)

150 Brocade Virtual ADX Global Server Load Balancing Guide
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Advanced GSLB configuration for IPv6
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Active bindings metric
You can configure the Brocade Virtual ADX to prefer an IP address with the highest number of
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 Brocade Virtual 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.
NOTE
By default, the active bindings metric is disabled. Once enabled, it is placed after the available
session capacity metric in the GSLB algorithm. You can change the metric order or enable or disable
other metrics, although we do not recommend this.
DNS response processing
When the active bindings metric is enabled, the GSLB Brocade Virtual 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 Brocade Virtual 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 Brocade Virtual 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 Brocade Virtual 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:
Virtual ADX(config-gslb-policy)#active-bindings
Syntax: [no] active-bindings
Use the show gslb dns detail command to view the active bindings for each IP address. Refer to
“Displaying DNS zone and hosts” on page 169 for sample output.