Coyote Point Systems Equalizer GX Series, Administration Manual

Page: 641 / 866

Layer 3 ICMP Probes
By default, Equalizer sends an Internet Control Message Protocol (ICMP) echo request (commonly
called a “ping”) to the IP address of every configured server object.
If a server does not respond to an ICMP echo request, Equalizer continues to issue any other
probes (TCP, ACV, server agent) configured for the cluster. This means, for example, that if TCP
and ICMP probes are both configured (the default), then a server can fail any number of ICMP
probes and will still be marked "UP" as long as it continues to respond to TCP probes.
If a server does not respond to an ICMP echo request and no other probes are configured, the
server is marked "DOWN", and Equalizer continues to send ICMP requests to the server’s IP
address. If an ICMP echo response is subsequently received, the server is marked "UP".
Responding to ICMP echo requests is an option on most server platforms. If ICMP echo reply is
disabled on one or more of the servers your configuration, then you may want to disable ICMP
echo requests on Equalizer to reduce traffic between Equalizer and the servers, and rely solely on
the other probing mechanisms.
Note - At least one ICMP probe of a server must have succeeded since the last Equalizer reboot, or failed ICMP probes
for the server will be ignored. This is done to avoid marking down a server that is configured to ignore ICMP Echo
Requests.
Copyright © 2014 Coyote Point Systems, A Subsidiary of Fortinet, Inc.
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Equalizer Administration Guide