Radware Alteon Application Manual page 500

Alteon Application Switch Operating System Application Guide
Health Checking
Script-based health checking only sends the appropriate requests to the relevant servers. Using the
script as shown in Figure 73 - Example Health Checking Script, page
only be sent to Real Server 1 and Real Server 2. Going through the health check statements serially
ensures that all content is available by at least one real server on the remote site.
The remote real server IP address (the virtual server IP address of the remote site) accepts "any"
URL requests. The purpose of the first GET in the script is to check if Real Server 1 or Real Server 2
is up. In other words, it checks if the remote site has at least one server for "images" content. Either
Real Server 1 or Real Server 2 responds to the first GET health check.
If all the real server IP addresses are down, Real Server 7 (the virtual server IP address of the
remote site) responds with an HTTP redirect (respond code 302) to the health check. As a result, the
health check fails, as the expected response code is 200, ensuring that the HTTP redirect messages
will not cause a loop.
Figure 73: Example Health Checking Script
>>/cfg/slb/group x/health script2/content none
>> /cfg/slb/advhc/script 2
open 80
send "GET /images/default.asp HTTP/1.1\\r\\nHOST: 192.192.1.2\\r\\n\\r\\n"
expect "HTTP/1.1 200"
close
open 80
send "GET /install/default.html HTTP/1.1\\r\\nHOST: 192.192.1.2\\r\\n\\r\\n"
expect "HTTP/1.1 200"
close
open 80
send "GET /script.cgi HTTP/1.1\\r\\nHOST: www.myurl.com \\r\\n\\r\\n"
expect "HTTP/1.1 200"
close
Example 3: A UDP-Based Health Check using Binary Content
Health check scripts can be designed to be sent over the UDP protocol with a few minor differences
from a TCP-based health check script. Due to the stateless nature of the UDP protocol, the CLOSE
command is not supported.
The following is an example UDP-based script that uses binary content to health check the UDP port
on a real server:
500
500, the first GET statement is
Document ID: RDWR-ALOS-V2900_AG1302