Brocade Virtual ADX Server Load Balancing Guide (Supporting ADX v03.1.00) - Manual (Page 55)

Brocade Virtual ADX Server Load Balancing Guide 39
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Sticky and concurrent connections
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The multiplier-value variable is a numerical value in the following range: 2 to 120. This value is
used to produce a sticky-age value for the virtual server it is configured under that is a multiple of
the value configured globally for the Brocade Virtual ADX as described in
“Setting the sticky age” on
page 37. For example, if the sticky age is configured to be 20 minutes, and the sticky-age-multiplier
to be 40, then the actual sticky age of the sticky sessions for the server will be 20x40= 800
minutes.
Note that even though the sticky-ages are multiplied, the show session command will still only
show ordinary age of the sticky sessions. The difference is that the age is incremented in a slower
pace when multiplier is applied. For example if the sticky-age-multiplier is configured to be 40, the
age counter in the session table is incremented once in 40 minutes instead of 1 minute.
NOTE
You can remove the multiplier by using the sticky-age-multiplier 1 or no sticky-age-multiplier number
command.
Sticky connection return from backup server to primary
You can designate real servers as primary servers or backup servers. A primary server is used by
the Brocade Virtual ADX when load balancing client requests for an application. A backup server is
used by the Brocade Virtual ADX only if all the primary servers are unavailable for the requested
application.
In a configuration where one real server is configured as a primary server and another is
configured as a backup, the virtual server can have the sticky option enabled, which ensures that
new connections are sent to the primary server, and a sticky session to a given port is created that
points to that primary server.
If the primary server goes down, new connections are sent to the backup server, and a sticky
session to the port is created that points to the backup server. The sticky session to the
(inoperative) primary server is deleted. When the primary server becomes operative again, since
the sticky session to the backup server is still valid (that is, it has not aged out), new connections to
the port are still sent to the backup server. This is the default behavior.
You can optionally configure the Brocade Virtual ADX to send new connections for the port to the
primary server when it comes back up, even though there is a sticky session to the backup server.
To do this for the DNS port on virtual server v1, enter the following commands.
Virtual ADX(config)#server virtual-name-or-ip v1 192.168.9.210
Virtual ADX(config-vs-v1)#port dns lb-pri-servers
Virtual ADX(config-vs-v1)#port dns sticky
Virtual ADX(config-vs-v1)#port dns active-primary-overide-sticky
Syntax: port port active-primary-overide-sticky
When the active-primary-overide-sticky command is configured, if the primary server goes down
and then comes back up, any new connection to the DNS port is sent to the primary server. The old
sticky session to the backup server is deleted, and a new sticky session to the primary server is
created.
Group sticky: Layer 4 SLB to server group
Layer 4 load balancing to server groups is performed through a Group Sticky function. This sticky
behavior supports Group Sticky and Group Failover functionality.