Coyote Point Systems Equalizer GX Series, Administration Manual

Page: 402 / 866

Working with Clusters and Match Rules
Match Rules, the Once Only Flag, and Cookies
Since multiple client requests may be received on a single TCP/IP connection, Equalizer has a flag
(
once only
) that specifies whether to check the headers in every request received on a connection,
or to load balance based solely The
once only
flag is a cluster parameter on the
Networking
tab.
When using Match Rules, it is usually desirable to turn off the once only flag for the cluster so that
Equalizer matches against each individual request in a connection, not just the first one.
You can also enable or disable
once only
flag in the match rule
Configuration
screen (tab), to
override the setting on the cluster for any request that matches that rule. For example, if
once
only is enabled on a cluster and disabled on a match rule, any request that matches that match
rule’s expression will be load balanced as if once only were disabled on the cluster.
The following table shows how the setting of once only affects load balancing when a match rule
hit occurs:
match rule hit
on...
once only disabled once only enabled
...the first request
on a connection
If the request headers contain a cookie
specifying a server in the match rule’s
server list, send the request to the server
in the cookie.
Otherwise, send the request to the server
in the match rule’s server list that is
selected by the load balancing policy in
effect for the match rule.
Same as at left.
...second and
subsequent
requests on the
same connection
Same as above.
If the request headers contain a cookie
specifying a server in the match rule’s
server list, send the request to the
server in the cookie.
Otherwise, send the request to the
server that was selected by the first
request.
Note that Equalizer always honors a cookie that specifies a server in the match rule’s server pool
list, regardless of the setting of the
once only flag: the request is sent to the server pool specified
by the cookie. If, however, the cookie specifies a server pool that is not in the match rule’s server
list, the cookie is ignored.
Using Responders in Match Rules
Responders are used to send automated responses to clients when all the server pools in a match
rule are down. See
"Modifying a Responder"
on page 482 for a complete description of Responders as
well as examples of using Responders in Match Rules.
Managing Match Rules
The EQ/OS 10 Administration Interface allows you to create and modify match rules, without
requiring a detailed knowledge of the configuration language syntax used in the
eq.conf file. The
interface validates match rules before saving them so that all saved rules are syntactically
correct. For this reason, we recommend you use the interface to create and edit match rules,
rather than editing the configuration file.
402 Copyright © 2014 Coyote Point Systems, A Subsidiary of Fortinet, Inc.