Brocade Virtual ADX Server Load Balancing Guide (Supporting ADX v03.1.00) - Manual (Page 253)

Brocade Virtual ADX Server Load Balancing Guide 237
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Sample show commands
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For this change to take effect, you must save the change to the startup-config file, then reload the
software using the following commands.
Virtual ADX(config)#write memory
Virtual ADX(config)#end
Virtual ADX#reload
Configuring fast session aging
The Brocade Virtual ADX supports fast session aging. When fast session aging is enabled with the
server session-max-idle command, the Brocade Virtual ADX can rapidly age out sessions when the
number of available free sessions drops below specified threshold values.
The threshold values are specified as percentages of the maximum number of sessions available
on the Brocade Virtual ADX (the "max-sessions" value). The number of free sessions that trigger
fast session aging is calculated using the following formula.
number of free sessions = (max-sessions * threshold) / 100
For example, if the max-sessions value on the Brocade Virtual ADX is 500,000 sessions, and the
threshold is 30%, then fast session aging is triggered when the number of free sessions reaches
150,000 or fewer; that is (500,000 * 30) / 100.
Two thresholds can be configured for fast session aging: the fast-age threshold and the random
threshold:
• Fast-age threshold—When the number of free sessions drops below the fast-age threshold,
sessions older than a specified time are aged out.
• Random threshold—When the number of free sessions drops below the random threshold,
sessions are aged out randomly, without regard to session age. The random threshold can be
equal to or lesser than the fast-age threshold.
For example, if the fast-age threshold is reached, sessions as old as or older than a specified
amount of time (for example, 5 minutes) are aged out until the number of available sessions climbs
above 150,000. If the random threshold is reached, sessions are aged out at random until the
number of available sessions climbs above 150,000.
Fast session aging is disabled by default. To configure fast session aging, enter a command such
as the following.
Virtual ADX(config)#server session-max-idle 5 30 10
Syntax: [no] session-max-idle max-idle-time [fast-age-threshold random-threshold]
The max-idle-time variable specifies the number of minutes allowed for idle sessions when a
fast-age-threshold variable is configured. When the value specified in the fast-age-threshold
variable is reached, sessions that are the same as and older than the threshold are aged out until
the number of free sessions exceeds the value specified in the fast-age-threshold variable. The
value of the max-idle-time variable can be from 1 through 30 minutes. The default is 0 minutes
(disabled). To enable fast session aging, you must specify a value for the max-idle-time variable
that is greater than 0.
When the number of available sessions drops below the value specified in the fast-age-threshold
variable, sessions older than the value specified in the max-idle-time variable are aged out until the
number of free sessions exceeds the threshold. The value of the fast-age-threshold variable is
expressed as a percentage of the maximum number of sessions available on the Brocade Virtual
ADX. The value specified for the fast-age-threshold can be from 10 through 70 percent. The default
is 33 percent.