Information About Device Discovery
This section includes the following topics:
The Device Discovery feature creates devices in DCNM-LAN by connecting to a Cisco NX-OS device and retrieving data from the device, including its running configuration. DCNM-LAN can also discover Cisco NX-OS devices and network servers that are neighbors of the first device, which is known as the
Note Staring from Cisco NX-OS Release 5.2.2(a) the Cisco DCNM-LAN supports the discovery of the following modules:
N7K-F248XP-25 Line Card
N55-M16FP 16-Port FC GEM
N7K-C7010-FAB2 Fabric 2 module
N7K-C7018-FAB2 Fabric 2 module
N55-D160L3-V2 Daughter Card
N55-M160L3-V2 Line Card
N3K-C3048TP-1GE Layer 3 switch
N3K-C3016Q- 40GE Layer 3 switch
If the device supports virtual device contexts (VDCs), DCNM-LAN retrieves the running configuration of each VDC that is configured on the physical device. DCNM-LAN 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 DCNM-LAN.
When DCNM-LAN 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 Interface User Guide
DCNM-LAN uses a variety of protocols to discover devices and servers in your data center network. This section includes the following topics:
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 DCNM-LAN to discover devices that are one or more hops beyond the 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 DCNM-LAN 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 DCNM-LAN to manage the device.
DCNM-LAN supports CDP hops on some Cisco switches that run Cisco IOS software. Although DCNM-LAN cannot manage these devices, the Topology feature allows you to see unmanaged devices and the CDP links between unmanaged devices and managed devices.
Link Layer Discovery Protocol
Device discovery uses Link Layer Discovery Protocol (LLDP) to discover the network adapters of servers that are connected to Cisco NX-OS devices.
To discover network elements in a storage area network (SAN), DCNM-LAN uses Fibre Channel. DCNM-LAN can discover SAN switches, servers, and storage arrays.
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.
DCNM-LAN discovers devices in several phases, as follows:
1. CDP neighbor discovery—Discovers the topology of the interconnected devices, beginning with the seed device and preceding for the number of CDP hops specified when you initiate discovery.
2. Supported device selection—Determines which of the discovered devices are supported by DCNM-LAN. Discovery continues for the supported devices only.
3. Inventory discovery—Discovers the inventory of the devices selected in the previous phase. For example, if the device is a Cisco Nexus 7000 Series switch, inventory discovery determines the supervisor modules, I/O modules, power supplies, and fans. If the device is a Cisco Nexus 1000V switch, inventory discovery finds the Virtual Supervisor Module and Virtual Ethernet Modules.
4. Device configuration discovery—Discovers the details of feature configuration on each device, such as interfaces, access control lists, and VLANs.
5. Network discovery—Associates network features with the device configuration details discovered in the previous phase.
Cisco NX-OS System-Message Logging Requirements
To monitor and manage devices, DCNM-LAN depends partly on system messages that it retrieves from managed devices. This section describes the system-message requirements that all Cisco NX-OS devices must meet before they can be managed and monitored by DCNM-LAN.
This section includes the following topics:
Interface Link-Status Events Logging Requirement
Devices must be configured to log system messages about interface link-status change events. This requirement ensures that DCNM-LAN receives information about interface link-status changes. The following two commands must be present in the running configuration on the device:
logging event link-status enable
logging event link status default
To ensure that these commands are configured on the device, perform the steps in the “Verifying the Discovery Readiness of a Cisco NX-OS Device” section.
Devices must be configured to store system messages that are severity level 6 or lower in the log file.
Although you can specify any name for the log file, we recommend that you do not change the name of the log file. When you change the name of the log file, the device clears previous system messages. The default name of the log file is “messages.”
If you use the default name for the log file, the following command must be present in the running configuration on the device:
logging logfile messages 6
To ensure that this command is configured on the device, perform the steps in the “Verifying the Discovery Readiness of a Cisco NX-OS Device” section.
Logging Severity-Level Requirements
DCNM-LAN has minimum severity level requirements for some Cisco NX-OS logging facilities. All enabled features on a Cisco NX-OS have a default logging level. The logging level required by DCNM-LAN varies per logging facility but is often higher than the default logging level in Cisco NX-OS. For more information, see the “Automatic Logging-Level Configuration Support” section.
Automatic Logging-Level Configuration Support
DCNM-LAN provides support for automatic logging level configuration for all supported Cisco NX-OS releases with the exception of Cisco NX-OS Release 4.0, which is available on Cisco Nexus 7000 Series switches only. This section describes how DCNM-LAN supports automatic logging-level configuration. For information about manually configuring logging levels for Cisco NX-OS Release 4.0, see the “Verifying the Discovery Readiness of a Cisco NX-OS Device” section.
During Device Discovery
During device discovery, if DCNM-LAN finds that a logging level on a discovered device is below the minimum logging-level requirement for that logging facility, DCNM-LAN raises the logging level to meet the minimum requirement. If logging levels meet or exceed the requirements, DCNM-LAN does not change the logging levels during discovery.
At Feature Enablement in the DCNM-LAN Client
If you use the DCNM-LAN client to enable a feature on a device and the default logging level for the feature does not meet the minimum requirement, the DCNM-LAN client warns you that it will configure the logging level on the device to meet the requirement. If you reject the logging level change, DCNM-LAN does not enable the feature.
During Auto-Synchronization with Managed Devices
If you use another means, such as the command-line interface (CLI), to enable a feature on a managed device and the default logging level for the feature does not meet the minimum requirement, DCNM-LAN automatically configures the logging level to meet the requirement after DCNM-LAN detects that the feature is enabled.
If you use the CLI or any other method to lower a logging level below the minimum requirement of DCNM-LAN, after DCNM-LAN detects the logging level change, it changes the state of that device to unmanaged. When this occurs, the Devices and Credentials feature shows that logging levels are the reason that the device is unmanaged. You can use the Devices and Credentials feature to discover the device again. During rediscovery, DCNM-LAN sets logging levels that do not meet the minimum requirements.
When DCNM-LAN discovers a Cisco NX-OS device that supports VDCs, it determines how many VDCs are on the Cisco NX-OS device. In DCNM-LAN, 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 nondefault VDCs, ensure that each VDC meets the prerequisites for discovery. For more information, see the “Prerequisites for Device Discovery” section.
Performing Device Discovery
This section includes the following topics:
Verifying the Discovery Readiness of a Cisco NX-OS Device
Before you perform device discovery with DCNM-LAN, you should perform the following procedure on each Cisco NX-OS device that you want to manage and monitor with DCNM-LAN. This procedure helps to ensure that device discovery succeeds and that DCNM-LAN can effectively manage and monitor the device.
Note If you are preparing a physical device that supports virtual device contexts (VDCs), remember that DCNM-LAN considers each VDC to be a device. You must verify discovery readiness for each VDC that you want to manage and monitor with DCNM-LAN.
Step 1 Log into the CLI of the Cisco NX-OS device.
Step 2 Use the
command to access global configuration mode.
Step 3 Ensure that an RSA or DSA key exists so that secure shell (SSH) connections can succeed. To do so, use the
show ssh key rsa
show ssh key dsa
If you need to generate a key, use the
Note You must disable the SSH server before you can generate a key. To do so, use the no feature ssh command.
Step 4 Ensure that the SSH server is enabled. To do so, use the
show ssh server
If the SSH server is not enabled, use the
command to enable it.
Step 5 Ensure that CDP is enabled globally and on the interface that DCNM-LAN uses to connect to the device. Use the
show run cdp all
command to see whether CDP is enabled.
Step 6 Verify that the
logging event link-status default
logging event link-status enable
commands are configured.
switch(config)# show running-config all | include "logging event link-status" logging event link-status default logging event link-status enable
If either command is missing, enter it to add it to the running configuration.
Note The logging event link-status enable command is included in the default Cisco NX-OS configuration. The show running-config command displays the default configuration only if you use the all keyword.
Step 7 Verify that the device is configured to log system messages that are severity 6 or lower.
Note The default name of the log file is “messages”; however, we recommend that you use the log-file name currently configured on the device. If you change the name of the log file, the device clears previous system messages.
switch(config)# show running-config all | include logfile logging logfile logfile-name 6
command does not appear or if the severity level is less than 6, configure the
switch(config)# logging logfile logfile-name 6
Step 8 If the device is a Cisco Nexus 7000 Series switch that is running Cisco NX-OS Release 4.0, you must manually verify that the logging level configuration of the device meets the DCNM-LAN logging level requirements. To do so, follow these steps:
a. Determine which nondefault features are enabled on the device.
switch(config)# show running-config | include feature
b. View the logging levels currently configured on the device. The
show logging level
command displays logging levels only for features that are enabled. The Current Session Severity column lists the current logging level.
switch(config)# show logging level Facility Default Severity Current Session Severity -------- ---------------- ------------------------
Note You can use the show logging level command with the facility name when you want to see the logging level of a single logging facility, such as show logging level aaa.
c. Determine which logging levels on the device are below the minimum DCNM-LAN required logging levels. To do so, compare the logging levels displayed
on page 29-8
to the minimum DCNM-LAN required logging levels that are listed in
d. For each logging facility with a logging level that is below the minimum DCNM-LAN required logging level, configure the device with a logging level that meets or exceeds the DCNM-LAN requirement.
switch(config)# logging level facility severity-level
argument is the applicable logging-facility keyword from
is the applicable minimum DCNM-LAN required logging level or higher (up to 7).
e. Use the
show logging level
command to verify your changes to the configuration.
Step 9 Copy the running configuration to the startup configuration to save your changes.
switch(config)# copy running-config startup-config [########################################] 100%
You can discover one or more devices. When a discovery task succeeds, DCNM-LAN retrieves the running configuration and status information of discovered Cisco NX-OS devices.
You can perform Deep Discovery by selecting one task at a time. You can also select all or multiple devices in a single task at a time.
Note You cannot select multiple tasks or multiple devices across tasks at one instance.
Use this procedure for the following purposes:
To discover devices that are not currently managed by DCNM-LAN. For example, you should use this procedure when DCNM-LAN 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 DCNM-LAN already has discovered.
To rediscover the topology when CDP links have changed without rediscovering devices that DCNM-LAN has already discovered.
Note You must successfully discover a Cisco NX-OS device before you can use DCNM-LAN to configure the device.
BEFORE YOU BEGIN
Ensure that you have configured the Cisco NX-OS device so that the DCNM-LAN server can connect to it and successfully discover it. For more information, see the
Fundamentals Configuration Guide, Cisco DCNM for LAN, Release 5.x
“Verifying the Discovery Readiness of a Cisco NX-OS Device” section.
Determine the IPv4 address of the device that you want DCNM-LAN 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.
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 Click Here in the Device Discovery pane to perform Shallow Discovery of the devices in the Cisco DCNM Web Client. The shallow discovery result web page pops out.
There are four types of discovery, they are Fabric, LAN, VMWare, and SMI-S Storage.
Step 3 In the first table of Fabric, you can Edit, Remove, Add, Re-discover, Refresh and Purge unreachable devices or dead link in selected fabric.
– To edit the fabric— Check the box before the fabric you want to select, and click the edit icon as a pencil. You can edit the Fabric Name, check/uncheck to use/disuse SNMPv3/SSH and select the Auth-Privacy from the drop-down list. Enter the User Name and Password and select the Status as managed, unmanaged, or managedContinuously. (Optional)You can click the options button to input the UCS User Name and the UCS Password.
– To remove the fabric— Select the fabric that you want to remove, and click the remove icon. Click yes to remove the selected fabric.
– To add a fabric— Click the add icon to add a fabric. Enter the information about Fabric Seed Switch, SNMP, User Name and Password. If you check Limit Discovery by VSAN, select which you want to limit by, Included VSAN List or Excluded VSAN List, and provide the VSAN List. Check/uncheck to enable/disable NPV Discovery in All Fabrics. (Optional)Click options buttion to input the UCS User Name and the UCS Password.
– To re-discover a fabric— Select the fabric that you want to be re-discovered, and click the Re-discover Fabric icon. Click yes to perform re-discovery of the fabric.
– To refresh the fabric discovery table— Click the refresh icon to manually refresh the discovery table.
– To purge down elements in the fabric— Select the fabric and click the Purge icon to purge unreachable devices or dead links in selected Fabric and click yes.
– To maximize the fabric table— Click the Maximize icon to maximize the fabric table and click Normalize to return the former view.
Step 4 In the second table of LAN discovery, you can Add, Refresh, Purge unreachable devices or dead links in selected LAN and Toggle between Task and Device View. You can Edit LAN Task, Re-discover LAN and Remove LAN Task/Switch by clicking the icons before the tasks/switches.
– To Edit LAN Task— Click the Edit icon, enter the username of a user account on the device in the User Name field. The user account must have a network-admin or vdc-admin role. In the Password field, enter the password for the user account. Choose the Status of the LAN task. For Catalyst 6500 devices, enter the enable password in the Enable Password field to allow for IOS privileged EXEC mode commands.
– To Re-discover LAN— A warning message pops out, click on yes to proceed rediscovery.
– To Remove LAN Task— Click on the remove icon and click yes to remove the LAN task.
– To Add LAN Task— Choose the Discovery Type from Hops from Seed Switch/Switch List/FWSM.
If you choose the discovery type as Hops from Seed Switch, input the IP address or IP range string in Seed Switch. Drag the triangle to the number which represents the Max Hops from Seed. Choose the Protocol of the LAN. If you choose SNMPv1, select the Scan Timeout from the drop-down list and enter the Community. If you choose SNMPv3/CLI, select the auth-privacy and Scan Timeout from the drop-down list. Enter the User Name and Password. Select the group that you want to add the switch to and click Next. Shallow LAN Discovery window shows up. Select the switches and click Add to add the LAN task.
It’s quite similar with the other discovery type as Switch List or FWSM, only that you don’t need to provide the max hops from seed.
Step 5 If there are VMWare and SMI-S storage devices discovered, you can perform similar function in the VMWare and SMI-S Storage discovery table.
Step 6 You can only perform deep discovery in the DCNM LAN client, please follow the steps in Deep Discovery.
Deep discovery is an ssh based discovery initiated from the DCNM-LAN client and allows DCNM to actually log in via ssh and configure the LAN devices.
To perform Deep Discovery of the devices so that you can configure LAN devices via DCNM, please follow below steps:
Step 1 From the Feature Selector pane, choose DCNM Server Administration > Device Discovery.
Step 2 Click the plus icon to expand the task under Task based Discovery pane, a list of devices under the single task shows up.
Step 3 You can either select one device or multiple devices under one task. Right click on the single device or multiple devices under one task and select Deep Discovery.
Note Deep Discovery is a requirement for any of the features found in the DCNM LAN client.
Step 4 Click Refresh button or press F5, the successfully deep discovered device will show MANAGED under SSH/Telnet of Status.
Step 5 You can also right click the discovered devices and select Re-do deep discovery.
Step 6 In the Device Discovery pane, click the History button to open the History of Discovery window. You can see Task ID, Owner, Seed Device IP Address, Discovered Time, Reason and Status history from the window.