Discovery overview
Discovery scans the devices in your network and sends the list of discovered devices to inventory.
Discovery also works with Device Controllability to configure the required network settings on devices when these settings are missing from devices.
There are four ways to discover devices:
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Use Cisco Discovery Protocol (CDP) and provide a seed IP address.
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Specify a range of IP addresses. You can include up to 4096 devices in the range.
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Use Link Layer Discovery Protocol (LLDP) and provide a seed IP address.
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Use Classless Inter-Domain Routing (CIDR) and provide a seed IP address.
When you configure the Discovery criteria, you can use settings to reduce the time needed to discover devices:
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CDP Level and LLDP Level: If you use CDP or LLDP as the Discovery method, you can set the CDP or LLDP level to indicate the number of hops from the seed device that you want to scan. The default, level 16, might take a long time on a large network. If you need to discover fewer devices, set the level to a lower value.
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Prefix Length: If you use CIDR as a discovery method, you can set the prefix length value, which ranges from 20 to 30. The default value is 30.
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Subnet Filters: If you use an IP address range, you can specify devices in specific IP subnets for Discovery to ignore.
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Preferred Management IP: Whether you use CDP, LLDP, CIDR, or an IP address range, you can specify whether you want Catalyst Center to add any of the device's IP addresses or only the device loopback address.

Note
For Cisco SD-Access Fabric and Cisco Catalyst Assurance, specify the device loopback address.
Regardless of the method you use, you must be able to reach the device from Catalyst Center and configure specific credentials and protocols in Catalyst Center to discover your devices. These credentials can be configured and saved in the window or on a per job basis in the Discovery window.
![]() Note |
If a device uses a first hop resolution protocol, such as Hot Standby Router Protocol (HSRP) or Virtual Router Redundancy Protocol (VRRP), the device can be discovered and added to the inventory along with its floating IP address. Later, if HSRP or VRRP fails, the IP address might be reassigned to a different device. This situation can cause issues with the data that Catalyst Center retrieves for analysis. |
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