Cisco ISE Predeployment Network Discovery Probe
A network engineer is in the predeployment discovery phase of a Cisco ISE deployment and must discover the network. There is an existing NMS in the network. Which type of probe must be configured to gather the information?
Community Insight
The question tests knowledge of Cisco ISE probes, specifically distinguishing between active scanning (NMAP) and passive/management-based discovery (SNMP) during the predeployment phase.
This page clarifies which probe type is required for network discovery in the Cisco ISE predeployment phase when an existing NMS is present. It establishes that SNMP is the correct choice for gathering device information from the management system.
Many learners incorrectly choose NMAP because it is a well-known network discovery tool, failing to recognize that the presence of an existing NMS makes SNMP the more appropriate and less disruptive method for integration.
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Expert Analysis
Why the Answer Is Correct
In the predeployment discovery phase of a Cisco Identity Services Engine (ISE) deployment, the goal is to identify endpoints and network devices to create policies. When an existing Network Management System (NMS) is present, the most efficient way to discover the network topology and device attributes is by using the Simple Network Management Protocol (SNMP). Cisco ISE can integrate with the NMS via SNMP to pull inventory data, such as IP addresses, MAC addresses, and device types, without generating additional network traffic or disrupting operations. This aligns with objective 4.2, which covers implementing probes.Why the Other Options Are Wrong
NMAP (Option B) is an active scanning tool used for discovering hosts and services by sending packets. While effective for discovery, it is generally not the primary method recommended for integrating with an existing NMS in a production environment due to potential noise and security concerns. NetFlow (Option C) is used for traffic analysis and monitoring, not for initial device discovery and inventory gathering. RADIUS (Option D) is an authentication protocol; while ISE uses RADIUS for authenticating users, it does not serve as a probe to discover network devices or their attributes in the context of predeployment setup.Community Comment Notes
Community feedback shows a split between SNMP and NMAP. Some users argue for NMAP based on its general reputation for discovery, but others correctly point out that the mention of an "existing NMS" implies leveraging established management protocols like SNMP. One commenter noted that "SNMP should work" given the context, which aligns with best practices for minimizing disruption. Another user suggested RADIUS, but this misunderstands the role of probes versus authentication methods. The consensus among experienced practitioners favors SNMP for NMS integration.Exam Strategy
Always look for contextual clues like 'existing NMS' or 'passive discovery' which often point towards SNMP or syslog integrations rather than active scanning tools like NMAP. Understanding the specific role of each probe type (SNMP vs. NMAP vs. NetFlow) is critical for these scenario-based questions.
Frequently Asked Questions
Why not use NMAP for network discovery?
NMAP is an active scanner that generates traffic. When an NMS exists, SNMP is preferred for passive, low-disruption integration.
Can RADIUS be used as a discovery probe?
No. RADIUS is an authentication protocol. Probes like SNMP are used to discover device attributes and inventory.