Cabletron Systems 9032578-05 manual Setting Server Status, Verifying Extended Content

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:

Specify application verification	load-balance set group-options <group
for all servers in specified 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	load-balance set server-options <ipaddr>
for specified server.	port <port number> acv-command
	<command string> acv-reply<reply string>
	read-till-index <reply string> [check-
	port <port-number>][acv-quit<quit
	string>]

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.”

SmartSwitch Router User Reference Manual 237