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Forcing Discovery of Remote Networks
The WebNMS discovery engine, by default, discovers all the networks (to which the management station running the WebNMS server is connected). It also adds any other network that it comes across (through router) to the topology and makes that network object unmanaged, which means no discovery will go on.
If you want to add a remote network and also perform discovery on that network, it can be done using the Discover option in the Discovery Configurator.
To enable discovery of remote networks
Click the Network Discovery tab in the Discovery Configurator.
Select Discover.
Select Entire Network.
Enter the network address in IPAddress and sub-netmask of the network in Netmask.
Click Add. The IP Address and Netmask is added to the screen with the Discover column enabled (checked), that is, discovery of those remote networks is enabled. Multiple networks can be configured by adding more IPAddresses and NetMask.
Discovering Range of IPs in a Network
To discover only a range of ipaddresses in a network
Click the Network Discovery tab in the Discovery Configurator.
Select Discover.
Select Set of Nodes. The Start IP and the End IP text boxes are enabled.
Enter the network address in IPAddress and sub-netmask of the network in NetMask fields.
Enter the starting IP address and the ending ipaddress in the range of ipaddresses to be discovered in Start IP and End IP respectively.
Click Add. Multiple Range of ipaddresses in a single network can also be configured.
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Note: The range of IPs specified here will not be discovered and added, if any of the node properties is specified in the Disallow Criteria. Hence, ensure that the properties of the IPs specified here are not specified in the Disallow Criteria. |
Configuring DHCP Support for Discovery
To enable DHCP support
Click the Network Discovery tab in the Discovery Configurator.
Select Discover.
Select Set of Nodes. The Start IP and the End IP text boxes are enabled.
Enter the network address in IPAddress and sub-netmask in NetMask fields.
Enter the starting IP address and the ending ipaddress in the range of ipaddresses to be discovered in the Start IP and the End IP respectively.
Select DHCP. Only when the Start IP and the End IP are given with the DHCP option disabled, will that particular range of network get discovered. But if Start IP and End IP are specified with DHCP option enabled then the nodes in that particular range will be discovered as DHCP Nodes and other nodes will also be discovered as Non-DHCP nodes.
Click Add.
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Note: Discovering/pinging only the devices specified in the range when DHCP is enabled is not supported in WebNMS. |
Example:
When you want to discover devices that support DHCP in a network "129.253.229.0", wherein you know only the range of IP addresses from 129.253.229.100 to 129.253.229.150 which are in the DHCP range,
Enter the IPAddress as 129.253.229.0
Enter the NetMask as 255.255.0.0
Enter the Start IP as 129.253.229.100
Enter the End IP as 129.253.229.150
Enable DHCP option
The above entry will discover and add the nodes with the range 129.253.229.100 to 129.253.229.150 with the "DHCP" enabled. This will also add all the other nodes in the network 129.253.229.0 with DHCP disabled.
Performing Network Specific Discovery of SNMP Devices
WebNMS discovery module facilitates discovering the SNMP (v1, v2c, and v3) devices in a specific network or a range of devices in a network.
Discovering SNMP (v1 and v2c) devices with specific Community and Port in a network
The WebNMS discovery engine, by default, uses the community string public and the agent port 161 while discovering SNMP devices. But some devices in the network could use a different port and community.
To discover those devices in a particular network
Click the Network Discovery tab in the Discovery Configurator.
Select Discover.
Select SNMP.
Click SNMP Properties. The Snmp Properties dialog box is displayed.
Click V1 or V2 version as required. The SNMP Properties panel is enabled.
Enter the community of the node in Community field.
Enter the port in SNMP Agent Port field.
Click OK.
Save this configuration in the Discovery Configurator.
On performing this, the discovery engine discovers those SNMP devices in the specified network with the configured community and port.
Discovering SNMPv3-Enabled Devices in a Network
SNMPv3 discovery for specific networks is useful under the following two situations:
a) When only certain network has SNMPv3 devices, sending v3 queries for all the networks to be discovered would be redundant. Hence, only specific networks should be configured for v3 discovery. The following are the configurations to be made for this situation.
Disable SNMPv3 Discovery option in SNMP Properties dialog box.
Click Network Discovery in the Discovery Configurator.
Select Discover and specify the IPAddress and NetMask of network that should be discovered as v3.
Select SNMP and click SNMP Properties. The Snmp Properties dialog box is displayed.
Select V3. The SNMP V3 Properties panel is enabled.
Click Add. The SNMP V3 Properties dialog box is displayed.
In the General tab enter the security user name, context name and the port number in the User Name, Context Name, and Agent Port fields respectively.
In the Security tab, select the security level from Security Level combo box. Enter the authentication protocol name and authentication password in Auth Protocol and Auth Password fields respectively. For AuthPriv security level, enter the privacy protocol and privacy password in Priv Protocol and Priv Password field respectively.
Click OK.
Click Add.
In this setup, the discovery engine will send SNMP v3 queries only to the specific networks or set of nodes that are configured. If the v3 queries to devices in the specific network fail, then v2 and v1 queries are sent to the devices. If any of these succeeds, the device will be added with to appropriate version set to it.
b) Also for a particular network, if the common username and contextname specified should not be used and you want to override the common configurations specified for this network, you can use this network-specific SNMP configuration. The configurations to be made for this situation are:
Enable SNMPv3 Discovery option and give the User Names, Context Name, and SNMP_Ports in the SNMP Properties dialog box.
Click Network Discovery in the Discovery Configurator.
Select Discover and specify the IPAddress and NetMask for the network whose v3 configurations should be overridden.
Select SNMP and click SNMP Properties. The Snmp Properties dialog box is displayed.
Select V3. The SNMP V3 Properties panel is enabled.
Click Add. The SNMP V3 Properties dialog box is displayed.
In the Network Discovery dialog box, in the General tab, override the common configurations that you want.
For overriding user name, use User Name option
For overriding context name, use Context Name option
For overriding SNMP port, use Agent Port option
In the Security tab, select the security level from Security Level combo box. Enter the authentication protocol name and authentication password in Auth Protocol and Auth Password fields respectively. For AuthPriv security level, enter the privacy protocol and privacy password in Priv Protocol and Priv Password field respectively.
Click OK.
Click Add.
It is enough if you override the necessary properties alone. The values of those properties that are not specified in the Network Discovery tab will be taken from the common values.
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Note: During discovery, sometimes the SNMPv3 devices are discovered as SNMPv2 devices. This occurs when the timeout or retries value is less. Hence to avoid this, set the SNMP Timeout or the SNMP Retries more than the default optimal value based on your agent's performance. These values can be configured in the Initial Parameters UI. |
To prevent the discovery of specific network
Click Network Discovery in the Discovery Configurator.
By default, the Discover option is selected. Disable (uncheck) this option.
Save the configuration.
This will prevent the network from being discovered and added to the topology database. Multiple networks can be prevented by adding more IP addresses and Netmasks.
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Note: This tag will not add the specified network, even if the network is reachable from the host in which the WebNMS is running. |
In the Network Discovery tab of the Discovery Configurator, you can delete a network entry specified in it by clicking the Delete button. Deleting an entry in the Discovery Configurator, will not delete that network from the database. This will delete the entry for the network only in the seed.file. Hence, when you restart the server without reinitializing it, then that particular network will be discovered again as its entry is retained in the database. Similarly when the discovery engine is scheduled for rediscovery, that network will be rediscovered (if rediscovery is enabled ).
As the Discovery Configurator acts as a medium to put the entries in the seed.file, all modifications done using this tool will effect only in the seed.file and will not have an impact on the database.
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