Brocade Virtual ADX Global Server Load Balancing Guide (Supporting ADX v03.1.00) - Manual (Page 167)

Brocade Virtual ADX Global Server Load Balancing Guide 157
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Advanced GSLB configuration for IPv6
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NOTE
The administrative preference metric is disabled by default and must be enabled before it is used
in the GSLB policy algorithm. Once enabled, it is placed after the available session capacity metric.
Refer to
“Disabling or re-enabling individual GSLB policy metrics” on page 144.
Configuring administrative preference for a site
Once enabled, the default administrative preference for sites is 128. You can change the
preference on an individual site basis.
Typically, you can set the administrative preference for a site ADX device when you define a site. For
example, to set the administrative preference for a site ADX device to 255, enter a command such
as the following:
Virtual ADX(config)#gslb site us
Virtual ADX(config-gslb-site-us)#si-name slb-1 2001:db8::56 255
To change the preference for a site ADX device you have already configured, use the same
command syntax. You do not need to reconfigure other site parameters when you change the
preference. For example, to change the preference for a site ADX device from the default (128) to
200, enter a command such as the following:
Virtual ADX(config)#gslb site us
Virtual ADX(config-gslb-site-us)#si-name slb-2 2001:db8::56 255 200
Least response selection metric
If multiple sites still compare equally based on all the metrics above, the GSLB Brocade Virtual ADX
selects the site that it has selected least often before. For example, if the GSLB Brocade Virtual
ADX has selected Site 1 and placed its IP address on top in 40% of the DNS replies, but has
selected Site 2 60% of the time, then in this instance the GSLB Brocade Virtual ADX selects Site 10.
To display the response selection percentages for the sites you have configured, use the show gslb
dns zone command. For more information, refer to
“Displaying DNS zone and hosts” on page 169
This metric is a tie-breaker in case multiple addresses pass through all the above comparisons
without one address emerging as the best choice. If this occurs, the address of the site that has
been selected least often in previous DNS responses is selected.
Least response selection is enabled by default. You can disable the metric only by enabling the
round robin selection metric to act as the tie breaker instead. See the following section.