Network Router User Manual

SmartSwitch Router User Reference Manual 237
Chapter 17: Web Hosting Configuration Guide
Verifying Extended Content
You can also have the SSR verify the content of an application on one or more load
balancing servers. For this type of verification, you specify the following:
• A string that the SSR 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 that the SSR will use 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 SSR 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 SSR to send a specific string to close a connection on a
server.
You can verify an application by entering the following Configure mode commands:
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.”
Specify application verification
for all servers in specified group.
load-balance set group-options <group
name>
acv-command <command string> acv-
reply
<reply string> read-till-index
<reply string> [check-port <port-
number>
][acv-quit <quit string>]
Specify application verification
for specified server.
load-balance set server-options <ipaddr>
port <port number> acv-command
<command string> acv-reply <reply string>
read-till-index <reply string> [check-
port
<port-number>][acv-quit <quit
string>
]