Discovery and Device Inventory function as one service. The process of finding network devices is known as Discovery. The Discovery function scans the devices in your network and sends the list of discovered devices to Device Inventory. Device Inventory retrieves and saves the details about the devices in its database. Device Inventory refreshes every 25 minutes for each device. (At any given time, Device Inventory may be refreshing data for several devices at a time.)
There are two methods for discovering devices:
Regardless of the method you use, you must be able to reach (ping) the device from DNA Center, and you need to configure specific credentials and protocols in DNA Center to discover your devices. These credentials can be configured globally in the Device Credentials page or on a per-job basis on the Discovery page. (Credentials configured in Discovery may be saved to use later as global credentials.)
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CLI credentials
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Simple Network Management Protocol (SNMPv2c or SNMPv3) credentials
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HTTPS credentials (These credentials are required only for discovering devices running Cisco Network Function Virtualization Infrastructure Software (NFVIS).)
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SSH/Telnet protocol
Because the various devices in a network can have different sets of credentials, you can configure multiple sets of credentials in DNA Center. The discovery process iterates through all of the sets of credentials until it finds a set that works for the device.
For discovery, one set of CLI credentials and one set of SNMP credentials (SNMPv2c Read, SNMPv2cWrite, or SNMPv3) is mandatory. If valid sets of credentials are provided for both SSH and Telnet, SSH credentials will be picked because SSH is more advanced than Telnet. If all three sets of valid SNMP credentials are provided, SNMP v3 will be picked because it's the most advanced protocol of the three.
After discovering devices, Device Inventory retrieves the details about the devices, such as host IP addresses, MAC addresses, and network attachment points, using one of the following protocols, as required:
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Link Layer Discovery Protocol (LLDP)
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IP Device Tracking (IPDT) is enabled automatically for the network fabric during the provisioning.
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LLDP Media Endpoint Discovery (LLDP-MED) (This protocol is used to discover IP phones and some servers.)
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Network Configuration Protocol (NETCONF) (Only required for devices running NFVIS.)
For information about configuration requirements for specific device types, see Discovery Prerequisites.