Coyote Point Systems Equalizer GX Series, Руководство администратора

Страница: 675 / 866

Health Check Timeouts
Configure Health Check timeouts using either the CLI or the GUI.
Layer 3 Health Check Timeouts
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. The timeouts that control
Layer 3 Health Check probes are located in the global CLI context and on the
Global
tab in the GUI:
Layer 3 Health Check Parameters
(CLI Parameter)
Minimum Default Maximum Units
ICMP Probe Maximum Tries ( icmp_maxtries ) > 1 3 30 integer
ICMP Probe Interval ( icmp_interval ) 0 15.0 60.0 seconds
By default, ICMP health check probes are sent a maximum of 3 times every 15 seconds to every
configured server that has Layer 3 probes enabled. Within a 15-second probe interval, the delay
between successive ping requests to the same server is determined internally -- it can be as short
as one second to a server that is not responding to ICMP requests and can be 5 seconds or longer
when a server is responding to ICMP echo requests, depending on the amount of traffic that
Equalizer is currently processing.
If a server responds to an ICMP Health Check, it is marked "Layer 3 UP". If a server does not
respond to an ICMP echo request, it will be marked "Layer 3 DOWN" by Equalizer only if the
server has responded to at least one ICMP echo request since Equalizer was last rebooted. This
behavior accounts for the fact that many servers are configured by default to never respond to
ICMP echo requests as a security precaution. In other words, if a server has never responded to a
Layer 3 health check probe since the last reboot, it is never marked "Layer 3 Down".
Note
- 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 in 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.
Layer 4 TCP and ACV Health Check Timeouts
By default, Equalizer sends TCP Health Checks to every server instance object in every server
pool. Equalizer and the server exchange a three-way TCP handshake to open a TCP connection. If
Active Content Verification (ACV) is also configured, the ACV probe takes place after the TCP
connection is established. Once the handshake is complete and ACV data is optionally exchanged,
the probe connection is closed.
The controls to enable Layer 4 Health Checks are located on a server instance and on the server
pool in which server instances reside:
GUI Parameter (CLI Parameter) Location Description
Probe Layer 4 ( probe_l4 ) server instance
A flag on a server instance, enabled by default. If
disabled, no TCP or ACV probes are sent to the server
instance.
Copyright © 2014 Coyote Point Systems, A Subsidiary of Fortinet, Inc.
All Rights Reserved. 675
Equalizer Administration Guide