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Cisco Intrusion Prevention System Sensor CLI Configuration Guide for IPS 7.2
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Appendix A System Architecture
SwitchApp
Caution
You receive a warning message if you have enabled global correlation, but you have not configured a
DNS or HTTP proxy server. This warning is a reminder to either disable global correlation or add a DNS
or HTTP proxy server.
For More Information
For the procedure for adding a DNS or proxy server to support global correl ation, see Changing Network
Settings, page 3-2.

Error Events

Whenever a global correlation update fails, an evError event is generated. The error message is included
in sensor statistics. The following conditions result in a status message with the severity of Error:
The sensor is unlicensed
No DNS or HTTP proxy server is configured
The manifest exchange failed
An update file download failed
Applying or committing the update failed
An evError event is generated with the severity level of Warning if you edit and save either the host or
global correlation configurations so that global correlation is enabled, but no DNS o r HTTP proxy
servers are configured.
For More Information
For the procedure for displaying sensor statistics, see Displaying Statistics, page 17-28.
SwitchApp
The 4500 series sensors have a built in switch that provides the external monitoring interfaces of the
sensor. The SwitchApp is part of the IPS 4500 series design that enables the InterfaceApp and sensor
initialization scripts to communicate with and control the switch. Any application that needs to get or
set information on the switch must communicate with the SwitchApp. Additionally the SwitchApp
implements the following:
Detects bypass—When the SensorApp is not monitoring, the SwitchApp places the switch in bypass
mode and then back to inspection mode once the SensorApp is up and running normally.
Collects port statistics—The SwitchApp monitors the switch and collects statistics on the external
interfaces of the switch for reporting by InterfaceApp.
Handles the external interface configuration—When you update the interface configuration, the
configuration is sent to the InterfaceApp, which updates the interface configuration for SwitchApp,
which then forwards that configuration on to the switch.