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Cisco Intrusion Prevention System Sensor CLI Configuration Guide for IPS 7.2
OL-29168-01
Chapter4 Configuring Interfaces
Understanding Interfaces
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The ASA IPS modules (ASA 5500-X IPS SSP and ASA 5585-X IPS SSP) do not support inline
VLAN pairs.
•
The ASA IPS modules (ASA 5500-X IPS SSP and ASA 5585-X IPS SSP) do not support VLAN
groups mode.
•
There are security consequences when you put the sensor in bypas s mode. When bypass mode is on,
the traffic bypasses the sensor and is not inspected; therefore, the sensor cannot prevent malicious
attacks.
•
As with signature updates, when the sensor applies a global correlation update, it may trigger
bypass. Whether or not bypass is triggered depends on the traffic load of the sensor and the size of
the signature/global correlation update. If bypass mode is turned off, an inline sensor stops passing
traffic while the update is being applied.
•
The ASA 5500-X IPS SSP an d the ASA 5585-X IPS SSP do not support bypass mode. The adaptive
security appliance will either fail open, fail close, or fail over depending on the configuration of the
adaptive security appliance and the type of activity being done on the IPS.
•
The show interface command output for the IPS 4510 and IPS 452 0 does not include the total
undersize packets or total transmit FIFO overruns.
•
When the IPS 4510 and IPS 4520 are configured in VLAN pairs, the packet display command does
not work without the VLAN option if the expression keyword is also used.
•
On the IPS 4510 and IPS 4520, no interface-related configurations are allowed when the SensorApp
is down.
Understanding Interfaces
This section describes the IPS interfaces and modes, and contains the following topics:
•
IPS Interfaces, page 4-2
•
Command and Control Interface, page 4-3
•
Sensing Interfaces, page 4-4
•
TCP Reset Interfaces, pag e 4-4
•
Interface Support, page 4-6
•
Interface Configuration Restrictions, page 4-8
•
Interface Configuration Sequence, page 4-10

IPS Interfaces

The sensor interfaces are named according to the maximum speed and physical location of the interface.
The physical location consists of a port number and a slot number. All interfaces that are built-in on the
sensor motherboard are in slot 0, and the interface card expansion slots are numbered beginning with
slot 1 for the bottom slot with the slot numbers increasing from bottom to top. Each physical interface
can be divided in to VLAN group subinterfaces, each of which consists of a group of VLANs on that
interface.
There are three interface roles:
•
Command and control
•
Sensing