Brocade Communications Systems ServerIron ADX 12.4.00 - Manual (Page 133)

ServerIron ADX Global Server Load Balancing Guide 121
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Host-level policies for site selection
1
When the ServerIron ADX compares the Flashback speeds, it compares the Layer 7
(application-level) Flashback speeds first, if applicable. If the application has a Layer 7 health
check and if the Flashback speeds are not equal, the ServerIron ADX is through comparing the
Flashback speeds. However, if only the Layer 4 health check applies to the application, or if further
tie-breaking is needed, the ServerIron ADX then compares the Layer 4 Flashback speeds.
To modify the application (Layer 7) tolerance, TCP (Layer 4) tolerance, or both, enter commands
such as the following:
GSLB-ServerIronADX(config)# gslb-host-policy abc

GSLB-ServerIronADX(config-gslb-host-policy-abc)# flashback application tolerance
30

GSLB-ServerIronADX(config-gslb-host-policy-abc)# flashback tcp tolerance 50
Syntax: [no] flashback application | tcp tolerance <num>
The application | tcp parameter specifies whether you are modifying the tolerance for the Layer 4
TCP health check or the Layer 7 application health checks. You can change one or both and the
values do not need to be the same. For each, you can specify from 0-100. The default for each is
10.
Enabling the Geographic metric
The geographic metric indicates the geographic location of a site. This metric is enabled by default,
which means the GSLB ServerIron ADX uses this metric when evaluating the sites in a DNS reply to
choose the best site.
To enable the Geographic metric for a host-level GSLB policy, enter commands such as the
following:
GSLB-ServerIronADX(config)# gslb-host-policy abc

GSLB-ServerIronADX(config-gslb-host-policy-abc)# geographic
Syntax: [no] geographic
Use the [no] form of the command to disable the Geographic metric.
Enabling the Health Check metric
To enable the Health Check metric for the host-level GSLB policy, enter commands such as the
following:
GSLB-ServerIronADX(config)# gslb-host-policy abc

GSLB-ServerIronADX(config-gslb-host-policy-abc)# health-check
Syntax: [no] health-check
Use the [no] form of the command to disable the Health Check metric.
NOTE
When both the Health Check metric and the Flashback metric are disabled for a host-level GSLB
policy, the GSLB ServerIron ADX will not perform any Layer 4 or Layer 7 health checks for the
hosts/zones for which the policy applies.
Changing the order of the metrics
You can change the order in which the GSLB ServerIron ADX applies the policy metrics for the
host-level policy. To change the order, specify the metrics in the desired order, such as the
following: