Riverstone Networks WICT1-12 - Manual (Page 505)

Riverstone Networks RS Switch Router User Guide Release 8.0 22-7
Web Hosting Configuration Load Balancing
Verifying Extended Content (Comprehensive Server Checking)
You can also have the RS verify the content of an application on one or more load balancing servers. For this type of
verification, specify the following:
• A string that the RS sends to a single server or to the group of load balancing servers. The string can
be a simple HTTP command to get a specific HTML page. Or, it can be a command to execute a
user-defined CGI script that tests the operation of the application.
• The reply that the application on each server sends back. The RS uses this reply to validate the
content. In the case where a specific HTML page is retrieved, the reply can be a string that appears
on the page, such as “OK.” If a CGI script is executed on the server, it should return a specific
response (for example, “OK”) that the RS can verify.
Note that you can specify this type of verification for a group of load balancing servers or for a specific server.
Application verification, whether a simple TCP handshake or a user-defined action-response check, involves opening
and closing a connection to a load balancing server. Some applications require specific commands for proper closure
of the connection. For example, a connection to an SMTP server application should be closed with the “quit”
command. You can configure the RS to send a specific string to close a connection on a server.
If you have a proprietary protocol, you can verify whether the protocol is “up” by specifying the files for the application
content verification request, reply and quit strings.
22.1.5 Using Health Check Clusters
The RS automatically performs health checks on its attached load balancing servers. It verifies the state of each server
and checks that an application session on the server can be established. When a load balancing server has multiple IP
addresses, you can configure a health check cluster so the RS health checks only one designated IP address instead of
all the IP addresses assigned to the server.
Following are the steps for configuring a health check cluster:
1. Create the health check cluster.
2. Add servers to the health check cluster.
3. Optionally, set parameters for the health check cluster.
The following example configures the “hcc1” health check cluster:
22.1.6 Setting Server Status
It may become necessary at times to prevent new sessions from being directed to one or more load balancing servers.
For example, if you need to perform maintenance tasks on a server system, you might want new sessions to temporarily
not be directed to that server. Setting the status of a server to “down” prevents new sessions from being directed to that
server. The “down” status does not affect any current sessions on the server. When the server is again ready to accept
new sessions, you can set the server status to “up.”
load-balance create health-check-cluster hcc1 ip-to-check 135.142.179.12 port-to-check
10
load-balance add-host-to-group 135.142.179.15-135.142.179.18 group-name hcc1
health-check-cluster hcc1