Coyote Point Systems Equalizer GX Series, Administration Manual

Page: 372 / 866

Working with Clusters and Match Rules
The
sticky time
period is the length of time over which Equalizer ensures that it directs new
connections from a particular client to the same server. The timer for the sticky time period
begins to expire as soon as there are no active connections between the client and the cluster. If
Equalizer establishes a new connection to the cluster, Equalizer resets the timer for the sticky
time period.
Sticky connections are managed on Equalizer using sticky records that record the IP address, port
and other information for the client-server connection. When you enable sticky connections, the
memory and CPU overhead for a connection increase. This overhead increases as the sticky time
period increases.
Consequently, you should use the shortest reasonable period for your application and avoid
enabling sticky connections for applications unless they need it. For most clusters, a reasonable
value for the sticky time period is 600 seconds (that is, 10 minutes). If your site is extremely
busy, consider using a shorter sticky time period.
With the
inter-cluster sticky
option, you can configure Equalizer to direct requests from a client to the
same server on any available port that has a current persistent connection in any cluster .
When Equalizer receives a client request for a Layer 4 cluster with inter-cluster sticky enabled and
the client does not have a sticky record for the cluster, then Equalizer will check other clusters
that have inter-cluster sticky enabled for a sticky record for the same client and server -- but on a
different server port than the one originally used in the client request.
If such a sticky record is found and the server IP/port in the sticky record is configured as a
server in the current cluster, then the sticky record is used to send the client request to that
server IP/port. Otherwise, the client request is load balanced across the server pool in the cluster.
In order for the inter-cluster sticky option to work:
l
The two clusters must have the same cluster IP address and different ports.
l
At least one server in each of the two clusters must be configured with the same IP address
and different ports.
Inter-cluster stickiness is provided for the case where you have similar services running on the
same server IP on two or more ports. Using
port ranges for a cluster achieves essentially the
same effect, without using another cluster IP address (See
"TCP Cluster Configuration Settings"
on
page 331). Using
inter-cluster sticky
is preferable in situations where you’d like the service available
on multiple cluster IPs as well as multiple ports.
To enable sticky connections for a cluster, follow these steps:
1. Log into the GUI using a login that has add/del access for the cluster (See
"Logging In"
on
page 230)
2. In the left frame, click the name of the Layer 4 TCP or UDP cluster to be configured. The
cluster’s parameters appear in the right frame.
3. Select the
Persistence
tab in the right frame.
4. In the
sticky time
field, specify the sticky time period in seconds greater than zero.
372 Copyright © 2014 Coyote Point Systems, A Subsidiary of Fortinet, Inc.