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

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receiving over a certain time period. This time period is known as the
Window Time. SLB sends the next request to the server that has received
the least number of connections during the last Window Time number of
seconds.
The Window Time is a setting that the administrator can change. The
default value is 10 seconds.
10.4.3. Selecting Stickiness
In some scenarios, such as with SSL connections, it is important that the same server is used for a
series of connections from the same client. This is achieved by selecting the appropriate stickiness
option and this can be used with either the round-robin or connection-rate algorithms. The stickiness
options are as follows:
Per-state Distribution This mode is the default and means that no stickiness is applied.
Every new connection is considered to be independent from
other connections even if they come from the same IP address or
network. Consecutive connections from the same client may
therefore be passed to different servers.
This may not be acceptable if the same server must be used for a
series of connections coming from the same client. If this is the
case then stickiness is required.
IP Address Stickiness In this mode, a series of connections from a specific client will
be handled by the same server. This is particularly important for
TLS or SSL based services such as HTTPS, which require a
repeated connection to the same host.
Network Stickiness This mode is similar to IP stickiness except that the stickiness
can be associated with a network instead of a single IP address.
The network is specified by stating its size as a parameter.
For example, if the network size is specified as 24 (the default)
then an IP address 10.01.01.02 will be assumed to belong to the
network 10.01.01.00/24 and this will be the network for which
stickiness is applied.
Stickiness Parameters
If either IP stickiness or network stickiness is enabled then the following stickiness parameters can
be adjusted:
• Idle Timeout
When a connection is made, the source IP address for the connection is remembered in a table.
Each table entry is referred to as a slot. After it is create, the entry is only considered valid for
the number of seconds specified by the Idle Timeout. When new connection is made, the table is
searched for the same source IP, providing that the table entry has not exceeded its timeout.
When a match is found, then stickiness ensures that the new connection goes to the same server
as previous connections from the same source IP.
The default value for this setting is 10 seconds.
• Max Slots
This parameter specifies how many slots exist in the stickiness table. When the table fills up
then the oldest entry is discarded to make way for a new entry even though it may be still valid
(the Idle Timeout has not been exceeded).
10.4.3. Selecting Stickiness Chapter 10. Traffic Management
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