D-Link DFL-1600 - Security Appliance, Руководство пользователя

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The consequence of a full table can be that stickiness will be lost for any discarded source IP
addresses. The administrator should therefore try to ensure that the Max Slots parameter is set to
a value that can accommodate the expected number of connections that require stickiness.
The default value for this setting is 2048 slots in the table.
• Net Size
The processing and memory resources required to match individual IP addresses when
implementing stickiness can be significant. By selecting the Network Stickiness option these
resource demands can be reduced.
When the Network Stickiness option is selected, the Net Size parameter specifies the size of the
network which should be associated with the source IP of new connections. A stickiness table
lookup does not then compare individual IP addresses but instead compares if the source IP
address belongs to the same network as a previous connection already in the table. If they belong
to the same network then stickiness to the same server will result.
The default value for this setting is a network size of 24.
10.4.4. SLB Algorithms and Stickiness
This section discusses further how stickiness functions with the different SLB algorithms.
An example scenario is illustrated in the figure below. In this example, the NetDefend Firewall is
responsible for balancing connections from 3 clients with different addresses to 2 servers. Stickiness
is enabled.
Figure 10.10. Connections from Three Clients
When the round-robin algorithm is used, the first arriving requests R1 and R2 from Client 1 are both
assigned to one sever, say Server 1, according to stickiness. The next request R3 from Client 2 is
then routed to Server 2. When R4 from Client 3 arrives, Server 1 gets back its turn again and will be
assigned with R4.
10.4.4. SLB Algorithms and Stickiness Chapter 10. Traffic Management
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