Prerequisites for discovery

NNMi uses SNMP, Web protocols (such as SOAP), and DNS while discovering and monitoring devices. NNMi Advanced can discover and monitor IPv6 addresses in addition to IPv4 addresses. To ensure accurate network topology information about your network environment, verify that your environment complies with the prerequisites.

Verify that your network ACL (Access Control Lists) configuration allows the NNMi management server to talk with the nodes you want NNMi to discover and monitor.

Verify that no firewall configuration in your network environment would block the NNMi management server's SNMP communication with the devices in your network.

Well-Configured DNS prerequisite

NNMi uses Domain Name System (DNS) to determine relationships between hostnames and IP addresses. This can result in a large number of nslookup requests.

Use nslookup to Verify DNS Server Configurations

Verify that your DNS servers are well configured to prevent long delays when resolving nslookup requests. This means the DNS server responding to NNMi nslookup requests has these qualities:

• The DNS server is an authoritative server and does not forward DNS requests.
• The DNS server has consistent hostname-to-IP address mappings and IP address-to-hostname mappings.
• If your network uses multiple DNS servers, all respond consistently to any particular nslookup request.

On the NNMi management server, verify that the following configuration settings in your environment:

• All operating systems: Locate your */etc/hosts file and ensure that the host file contains a minimum of two entries. When an nslookup command is not successful, this file takes over:

  127.0.0.1 (loopback loghost) or ::1
<NNMi_server_address> (the IP address of the NNMi management server)

  If your NNMi management server participates in a high availability (HA) environment, the virtual server name and IP-address is required in the */etc/hosts file in addition to the physical server name and IP-address.

  Windows: The following registry key determines the location of this file:

  \HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\DataBasePath

  Linux: This file is in the /etc directory.

• Windows: Use the Control Panel to navigate to your Network and Internet Connections configuration, Network Connections, Local Area Connections, Support tab, and click the Details button. Verify that all identified DNS servers provide consistent hostname-to-IP address mappings and IP address-to-hostname mappings.
• Linux: Ensure that the nslookup search path resolves to the nsswitch.conf file. See the nsswitch.conf(4) manpage that was provided with your operating system. Verify that all identified DNS servers provide consistent hostname-to-IP address mappings and IP address-to-hostname mappings.

Exclude Problem Devices from nslookup

You can populate two files that instruct nslookup to exclude certain addresses. The benefits of doing this are as follows:

• Speed up Spiral Discovery.
• Keep network traffic generated by NNMi to a minimum.

If you know there are problems with the DNS configuration in your network domain (hostnames or addresses that do not resolve properly), instruct NNMi to avoid nslookup requests for unimportant devices.

To identify problem devices, create the following two files before configuring NNMi discovery. NNMi never issues a DNS request for hostnames or IP addresses identified in these files:

• hostnolookup.conf — Enter fully-qualified hostnames or wildcards that identify groups of hostnames.
• ipnolookup.conf — Enter fully-qualified IP addresses or wildcards that identify groups of IP addresses.
  

Use an ASCII editor to populate the files. Place the files in the following location on the NNMi management server:

• Windows:
  %NnmDataDir%\shared\nnm\conf\
• Linux:
  $NnmDataDir/shared/nnm/conf/

Prerequisites for Web Agents

A Web Agent can be used to enable communication between NNMi and other programs.

Depending on which type of certificates your team uses, the steps required to configure NNMi vary. For example:

• Self-signed certificate (one per hypervisor)
• CA certificate (per organization, used to validate all hypervisors within the organization)

Prerequisites for SNMP Agents

Spiral Discovery uses SNMP while detecting devices and connections among the devices in your network environment. NNMi also uses SNMP as part of monitoring and reporting on the health of devices in your network environment.

NNMi supports the following SNMP versions:

• SNMPv1
• SNMPv2c
• SNMPv3
  

NNMi uses information gathered from Routers to establish membership for Subnet connections. Make sure that important Routers in your network environment are SNMP enabled.

NNMi uses either of the following criteria to identify a Router:

• The Router responds to an SNMP query with appropriate values for sysServices (1.3.6.1.2.1.1.7) and ipForwarding (1.3.6.1.2.1.4.1). See RFC 1213, MIB-II for details.
• The Router responds to an SNMP query with an appropriate MIB-II sysObjectID value according to the current settings in NNMi's Device Profile configuration.

You must provide the appropriate SNMP Community Strings to NNMi.

Before configuring NNMi discovery, complete the following steps:

1. Enable SNMP communication on important devices in your network (each device that you want NNMi to actively monitor).

   See the manufacturer's documentation for information about how to configure SNMP on each of your devices.

   • Establish read community strings for any SNMPv1 or SNMPv2c agents.
   • Establish the appropriate User-based Security Module (USM) level of security for authentication and privacy for any SNMPv3 agents.

2. Configure NNMi to use the appropriate read community strings (in the order you specify) or USM settings for your network environment.

Related topics

• Configure tenants
• Configure discovery