Coyote Point Systems Equalizer GX Series, Administration Manual

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Active Content Verification (ACV) Probes
Active Content Verification serves two purposes: L4 probing and L7 probing. It is a mechanism for
checking the validity of a server pool. When you enable ACV for a server pool, Equalizer requests
data from each server pool in a cluster and verifies that the returned data contains a character
string that indicates that the data is valid. You can use ACV with most network services that
support a text-based request/response protocol, such as HTTP.
Note - You cannot use ACV with Layer 4 UDP clusters.
ACV checking requires that the server instance is configured with L4 probing (
probe_l4
) on. This is
the default server instance configuration. To enable ACV, an ACV response string is configured for
a server pool.The ACV probe is limited to 99 characters, and must use only the printable ASCII
characters (decimal 32 to 126). Equalizer then searches for the ACV response string in the first
1024 characters of the server’s response to high-level TCP probes. If the ACV response string is
not found, the server is marked “DOWN”. An ACV query string can be specified if the service
running on the server’s probe port requires input in order to respond. If the TCP probe connection
is not established ACV probing will fail as well.
ACV is best explained using a simple example. HTTP protocol enables you to establish a
connection to a server, request a file, and read the result. The example below shows the
connection process when a user requests a telnet connection to an HTTP server and requests an
HTML page.
Equalizer can perform the same exchange automatically and verify the server pool’s response by
checking the returned data against an expected result.
You can test ACV on server pools on individual server instances or all server instances configured
for L4 probing using either the CLI or the GUI. To test using the CLI enter:
eqcli sp- spname > test si instance
To test on the GUI, click on the
Load Balance
configuration tab on the left navigational pane and
expand the
Server Pool
branch. Click on a
Server Pool
and then select the
Configuration
tab on the right.
Select a
Server to Test
using the drop down list in the
Test Layer 4 Probes
area at the bottom of the
screen and click on the
Test
button. You will receive an
ACV Test Notification
indicating that ACV
probing was executed successfully and whether a pass or fail entry was made into the Output log.
Copyright © 2014 Coyote Point Systems, A Subsidiary of Fortinet, Inc.
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Equalizer Administration Guide