ServerIron ADX Global Server Load Balancing Guide 35
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Configuring GSLB protocol parameters 1

TABLE 2 GSLB policy metrics
Metric Default Configuration options
Server (host) health Enabled.
The GSLB ServerIron ADX performs
Layer 4 health checks on the TCP or
UDP port and Layer 7 health checks
on the application, if the application
is known to the ServerIron ADX.
NOTE: If all the sites fail their health
checks, resulting in all the
sites being rejected by the
GSLB ServerIron ADX, the
ServerIron ADX sends the
DNS reply unchanged to the
client.
You can disable this metric.
NOTE: When both the health check
metric and the Flashback
metric are disabled, the
ServerIron ADX does not
perform any Layer 4 or Layer
7 health checks.
Weighted IP metric Disabled.
When enabled, the ServerIron ADX
distributes GSLB traffic among IP
addresses in a DNS reply, based on
weights assigned to the IP
addresses.
You can enable this metric and
assign weights to individual IP
addresses. The weight can be from
0 to 100. The default is 0.
You can disable this metric.
Weighted site me tric Disabled.
When the weighted IP metric is
enabled, the weighted site metric is
disabled. The weighted site metric is
an alternative to the weighted IP
metric. They are mutually exclusive.
When enabled, the ServerIron ADX
distributes SLB traffic among GSLB
sites based on weights configured
for the sites.
You can enable this metric and
assign weights to individual sites.
The weight can be from 0 to 100.
The default is 0.
You can disable this metric.
Session capacity threshold Enabled.
The default value for the threshold is
90%. Thus a site ServerIron ADX is
eligible to be the best site only if its
session utilization is below 90%.
You can change the threshold to a
value from 0-100%.
You can disable this metric.
Active bindings metric Disabled.
When enabled, the ServerIron ADX
selects an IP address with the
highest number of active bindings
as the best IP address for the client.
You can enable and disable this
metric.
Round-trip time (RTT) from remote
ServerIron ADXs to the DNS clients.
Enabled.
The default RTT cache interval is
120 seconds.
The default cache prefix length is 20
bits.
The default tolerance (used when
comparing otherwise equal sites) is
10%.
The default explore percentage is
5%.
You can change the RTT cache
interval, cache prefix length,
tolerance, and explore percentage
individually.
You can disable this metric. If you
disable RTT, the GSLB ServerIron
ADX instructs the site ServerIron
ADXs to stop sending RTT
information.
Geographic location Enabled. You can disable this metric.