Brocade Communications Systems 12.4.00 Enabling the Num-session metric, Syntax no num-session

Host-level policies for site selection 1

Enabling the Num-session metric

The capacity threshold specifies how close to the maximum session capacity the site ServerIronADX (remote ServerIron ADX) can be and still be eligible as the best site for the client. This mechanism provides a way to shift load away from a site before the site becomes congested. The GSLB ServerIron ADX uses this metric when evaluating the sites in a DNS reply to choose the best site.

To enable the num-session metric for a host-level policy, enter commands such as the following:

GSLB-ServerIronADX(config)# gslb-host-policy abc

GSLB-ServerIronADX(config-gslb-host-policy-abc)# num-session

Syntax: [no] num-session

Use the no form of the command to disable the Num-session metric.

Configuring the Num-session Tolerance

You can specify the percentage by which the number of available sessions on the site ServerIron ADX can differ from the number of available sessions on another site ServerIron ADX and still be considered an equally good site. To do this, enter commands such as the following:

GSLB-ServerIronADX(config)# gslb-host-policy abc GSLB-ServerIronADX(config-gslb-host-policy-abc)# num-session tolerance 20

Syntax: [no] num-session tolerance <num>

The <num> parameter specifies the maximum percentage by which the session table utilization on ServerIron ADXs at different sites can differ without the GSLB ServerIron ADX selecting one over the other based on this metric. You can specify a tolerance from 0-100. The default is 10.

Enabling the Preference metric

To enable the Preference metric for a host-level policy, enter commands such as the following:

GSLB-ServerIronADX(config)# gslb-host-policy abc

GSLB-ServerIronADX(config-gslb-host-policy-abc)# preference

Syntax: [no] preference

Use the no form of the command to disable the Preference metric.

Enabling the Round-Robin Selection metric

The round robin selection metric is an alternative to the least response selection metric as the final tie breaker. When you enable round robin selection, the GSLB ServerIron ADX automatically disables the least response selection metric, and instead uses the round robin algorithm for GSLB selection.

Use the round robin selection metric instead of the least response selection metric when you want to prevent the GSLB ServerIron ADX from favoring new or recently recovered sites over previously configured active sites.

The round robin selection metric is disabled by default. When you enable the metric, the software automatically disables the least response selection metric, since they are mutually exclusive. Likewise, if you disable the round robin selection metric, the software automatically re-enables the least response selection metric.

To enable round robin selection for a host-level policy, enter commands such as the following:

GSLB-ServerIronADX(config)# gslb-host-policy abc

GSLB-ServerIronADX(config-gslb-host-policy-abc)# round-robin

ServerIron ADX Global Server Load Balancing Guide	123
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