Information About Device Discovery
This section includes the following topics:
Device Discovery
The Device Discovery feature creates devices in Cisco DCNM by connecting to a Cisco NX-OS device and retrieving the running configuration of the device. Cisco DCNM can also discover Cisco NX-OS devices that are neighbors of the first device, which is known as the seed device.
If the device supports virtual device contexts (VDCs), Cisco DCNM retrieves the running configuration of each virtual device context (VDC) that is configured on the physical device. Cisco DCNM displays each VDC as a device, including the default VDC. If the Cisco NX-OS device has only the default VDC, then device discovery creates only one device in Cisco DCNM.
When Cisco DCNM connects to a device to retrieve its configuration, it uses the XML management interface, which uses the XML-based Network Configuration Protocol (NETCONF) over Secure Shell (SSH). For more information, see the
Cisco NX-OS XML Management Interface User Guide, Release 4.x
.
Cisco Discovery Protocol
Device discovery uses the Cisco Discovery Protocol (CDP) to find devices that are connected to the initial device in the discovery process. CDP exchanges information between adjacent devices over the data link layer. The exchanged information is helpful in determining the network topology and physical configuration outside of the logical or IP layer.
CDP allows Cisco DCNM to discover devices that are one or more hops beyond the first device (seed device) in the discovery process. When you start the discovery process using the Device Discovery feature, you can limit the number of hops that the discovery process can make.
After Cisco DCNM discovers a Cisco NX-OS device using CDP, it connects to the device and retrieves information, such as the running configuration of the device. The information collected allows Cisco DCNM to manage the device.
Cisco DCNM supports CDP hops on some Cisco switches that run Cisco IOS software. Although Cisco DCNM cannot manage these devices, the Topology feature allows you to see unmanaged devices and the CDP links between unmanaged devices and managed devices.
Credentials and Discovery
Device discovery requires that you provide a username and password for a user account on the seed device. To successfully complete the discovery of a Cisco NX-OS device, the user account that you specify must be assigned to either the network-admin or the vdc-admin role.
If you want to discover devices that are one or more hops from the seed device, all devices in the chain of hops must be configured with a user account of the same username and password. All Cisco NX-OS devices in the chain of hops must assign the user account to the network-admin or the vdc-admin role.
Virtualization Support
When Cisco DCNM discovers a Cisco NX-OS device that supports VDCs, it determines how many VDC are on the Cisco NX-OS device. In Cisco DCNM, each VDC is treated as a separate device. The status of each VDC is tracked separately and you can configure each VDC independently of other VDCs on a Cisco NX-OS device.
Before discovering a Cisco Nexus 7000 Series device that has non-default VDCs, ensure that each VDC meets the prerequisites for discovery. For more information, see the “Prerequisites for Device Discovery” section.
Performing Device Discovery
Figure 6-1 shows the Device Discovery content pane.
Figure 6-1 Device Discovery Content Pane
This section includes the following topics:
Discovering Devices
You can discover one or more devices. When a discovery task succeeds, Cisco DCNM retrieves the running configuration and status information of discovered Cisco NX-OS devices.
Use this procedure for the following purposes:
-
To discover devices that are not currently managed by Cisco DCNM. For example, you should use this procedure when Cisco DCNM has not yet discovered any devices, such as after a new installation.
-
To discover devices that you have added to your network without rediscovering devices that Cisco DCNM already has discovered.
-
To rediscover the topology when CDP links have changed, without rediscovering devices that Cisco DCNM has already discovered.
Note You must successfully discover a Cisco NX-OS device before you can use Cisco DCNM to configure the device.
BEFORE YOU BEGIN
Ensure that you have configured the Cisco NX-OS device so that the Cisco DCNM server can connect to it. For more information, see the “Cisco NX-OS Device Configuration Requirements” section.
Determine the IPv4 address of the device that you want Cisco DCNM to connect to when it starts the discovery task. This is the seed device for the discovery.
Determine whether you want to discover devices that are CDP neighbors of the seed device. If so, determine the maximum number of hops from the seed device that the discovery process can make.
Note The discovery process can perform complete discovery of neighbors only if the neighboring devices are configured with the same credentials as the seed device.
DETAILED STEPS
To discover one or more Cisco NX-OS devices, follow these steps:
Step 1 From the Feature Selector pane, choose
DCNM Server Administration > Device Discovery
.
The discovery tasks appear in the Discovery Tasks area of the Contents pane.
Step 2 In the Seed Device field, enter the IPv4 address of the device that you want Cisco DCNM to connect to when it starts the discovery task. Valid entries are in dotted decimal format.
Step 3 In the User Name field, enter the username of a user account on the device. The user account must have a network-admin or vdc-admin role.
Step 4 In the Password field, enter the password for the user account that you entered in the User Name field.
Step 5 (Optional) If you want Cisco DCNM to discover devices that are CDP neighbors of the seed device, in the Maximum Hops of Neighbors to Discover field, enter the desired maximum number of hops. By default, the maximum hops is 0 (zero).
Step 6 Ensure that
Rediscover Configuration and Status for Existing Devices
is unchecked. By default, this check box is unchecked.
By leaving this check box unchecked, you enable Cisco DCNM to use previously discovered devices as CDP hops without retrieving their running configuration and status information.
Step 7 Click
Start Discovery
.
After a short delay, the discovery task appears at the bottom of the list of tasks in the Discovery Tasks area. Cisco DCNM updates the task status periodically.
Step 8 Wait until the status for the task is Successful. This step may take several minutes.
After the status is Successful, you can use Cisco DCNM to configure and monitor the discovered devices.
You do not need to save your changes.
Rediscovering Devices
You can rediscover one or more devices.
Note Rediscovery replaces any configuration data that Cisco DCNM has for a Cisco NX-OS device with the configuration data retrieved during the rediscovery. If you need to discover one or more devices without retrieving configuration and status information for already discovered devices, see the “Discovering Devices” section.
You must successfully discover a Cisco NX-OS device before you can use Cisco DCNM to configure the device.
DETAILED STEPS
To rediscover one or more Cisco NX-OS devices, follow these steps:
Step 1 From the Feature Selector pane, choose
DCNM Server Administration > Device Discovery
.
The discovery tasks and their status appear in the Discovery Tasks area of the Contents pane.
Step 2 In the Seed Device field, enter the IPv4 address of the device that you want Cisco DCNM to connect to when it starts the discovery task. Valid entries are in dotted decimal format.
Step 3 In the User Name field, enter the username of a user account on the device. The user account must have a network-admin or vdc-admin role.
Step 4 In the Password field, enter the password for the user account that you entered in the User Name field.
Step 5 (Optional) If you want Cisco DCNM to rediscover devices that are CDP neighbors of the seed device, in the Maximum Hops of Neighbors to Discover field, enter the desired maximum number of hops. By default, the maximum hops is 0 (zero).
Step 6 Check
Rediscover Configuration and Status for Existing Devices
. By default, this check box is unchecked.
By checking this check box, you enable Cisco DCNM to replace any configuration and status information that it has about a previously discovered device with the running configuration and status information retrieved from the device.
Step 7 Click
Start Discovery
.
After a short delay, the discovery task appears at the bottom of the list of tasks in the Discovery Tasks area. Cisco DCNM updates the task status periodically.
Step 8 Wait until the status for the task is Successful. This step may take several minutes.
After the status is Successful, you can use Cisco DCNM to configure and monitor the discovered devices.
You do not need to save your changes.