Amer Networks E5Web GUI - Manual (Page 692)

that the routing table chosen must necessarily contain routes for all the servers in the SLB rule.)
Monitoring Methods
The method by which hosts are polled can be any combination of:
• ICMP
An ICMP "Ping" message is sent to the server.
• TCP
A TCP connection is established to and then disconnected from the server.
•
HTTP
An HTTP request is sent using a specified URL. Two extra pieces of data must be specified for
HTTP polling:
1. Request URL
The URL which is to be requested from all servers.
This must be specified to be either a FQDN or a Relative path. An example FQDN is
http://www.mydomain.com/path/file.txt and an example relative path is /path/file.txt.
If a relative path is specified then the path is concatenated to the IP address of the
server. For example, if the server IP is 10.12.14.01 then the relative path /path/file.txt
would become http://10.12.14.01/path/file.txt for the polling.
An FQDN must be used, however, when polling a server that is host to many virtual
servers.
2. Expected Response
A text string which is the beginning (or complete) text of a valid response. If no text is
specified, any response from the server will be considered valid.
Testing for a specific response text provides the possibility of testing if an application is
offline. If, for a instance, a web page response from a server can indicate if a specific
database is operational with text such as "Database OK", then the absence of that
response can indicate that the server is operational but the application is offline.
Monitoring with HTTP assumes that the URL entered is valid for all the servers in the SLB rule
so no DNS lookup needs to be done. An HTTP GET request is therefore sent straight to the IP
address of the server. (This differs from route failover host monitoring, where HTTP URLs are
resolved with a DNS lookup.)
All Server Polling Must Succeed
The polling methods configured for an SLB rule are all used on all the servers in the rule. If one
configured polling method fails but another succeeds on the same server, that server is
considered to be offline. In other words, all configured polling methods need to succeed on a
server for that server to be considered operational.
Polling Options
For each polling method specified, there are a number of property parameters that should be
set:
Chapter 10: Traffic Management
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