Administer > Configure communication protocol > Configure default SNMP, management address, and ICMP settings

Configure default SNMP, management address, and ICMP settings

NNMi generates network traffic using ICMP and SNMP protocols to discover and monitor your network environment. Default settings for the use of these protocols are provided; for example, timeout and retry behavior settings.

To configure the default communication protocol settings for your environment:

  1. Navigate to the Communication Configuration form.

    1. From the workspace navigation panel, select the  Configuration workspace.
    2. Select the Communication Configuration.

  2. In the far-left panel of the form, make your configuration choices

    • Default SNMP Settings (table below)

    • Management Address Selection settings (table below)

      The NNMi administrator can over-ride this setting and specify the management address on a per-node basis using the SNMP Agent Form.

    • Default ICMP Settings (table below)
  3. Click  Save and Close to apply your changes.
Default SNMP Settings Attributes
Attribute Description
Enable SNMP Address Rediscovery

The NNMi administrator can over-ride this setting for a Region or on a per-node basis.

If  enabled, NNMi automatically identifies which management address (SNMP agent) to use for each device. If the initially configured address becomes unreachable, NNMi automatically locates another address, if possible, and changes the management address attribute value. Click here for more information.

When NNMi first discovers a node, the seed address (provided by the NNMi administrator) or discovered address (for non-seeded nodes) becomes the initial address used for SNMP communication. After NNMi builds an inventory of all IP addresses associated with the node, NNMi follows a set of rules to determine which address is the best choice for each node's Management Address:

(NNMi Advanced) The NNMi administrator specifies whether NNMi prefers IPv4 addresses, IPv6 addresses, or dual-stack (both) when selecting the Management Address.

  1. NNMi ignores the following addresses when determining which Management Address is most appropriate:

    • Any address of an administratively-down interface.
    • Any address that is virtual (for example, VRRP).
    • Any IPv4 Anycast Rendezvous Point IP Address or IPv6 Anycast address.
    • Any address in the reserved loopback network range. IPv4 uses 127/24 (127.*.*.*) and IPv6 uses ::1.
    • Any IPv6 link-local address.
  2. If the NNMi Administrator chooses Enable SNMP Address Rediscovery  in Communication Configuration, NNMi prefers the last-known Management Address (if any).

  3. If the Management Address does not respond and the NNMi Administrator specifies Enable SNMP Address Rediscovery in Communication Configuration, NNMi uses the Communication Configuration settings for Management Address Selection. The NNMi Administrator chooses the order in which NNMi checks the following:

    • Seed IP / Management IP - If the NNMi Administrator configures a Seed, NNMi uses the Seed address (either a specified IP address or the DNS address associated with a specified hostname) only during initial Discovery. NNMi then requests the current Management Address (the address from which the node's SNMP Agent responds) and uses that IP address for all communication after initial discovery.
    • Lowest Loopback - If a node supports multiple loopback address, NNMi queries each loopback addresses, starting with the lowest number. NNMi uses the loopback address with the lowest number from which the SNMP agent responds (for example, 10.16.42.197 is a lower number than 10.16.197.42).
    • Highest Loopback - If a node supports multiple loopback address, NNMi queries each loopback addresses, starting with the highest number. NNMi uses the loopback address with the highest number from which the SNMP agent responds.
    • Interface Matching - The NNMi Administrator chooses which interface MIB variable NNMi queries to detect changes. NNMi can use the following MIB-II attribute values: ifIndex, ifName, ifDescr, ifAlias, or a combination of these (ifName or ifDescr, ifName or ifDescr or ifAlias). NNMi searches current database entries for information about the interface in this order: index, alias, name, and description. If multiple IP addresses are associated with the interface, NNMi starts by querying the lowest IP address and selects the first responding address in ascending order.
  4. If no response, NNMi queries any remaining IP addresses in the node's IP address inventory, starting with the lowest number. NNMi uses the address with the lowest number from which the SNMP agent responds.

  5. If no response, NNMi checks for any Mapped Address configured for one of the currently known addresses (see the Mapped Address column in the Custom IP Addresses view).

    The address represents a static Network Address Translation (NAT) pair's external IP address from the internal/external IP address pair. NNMi Administrators configure these pairs using the Overlapping IP Address Mapping form. NNMi uses this list of addresses starting with IPv4 from low to high, then IPv6 from low to high.

  6. If no response, NNMi might be configured to repeat the sequence using SNMPv1, SNMPv2c, or SNMPv3 in the order specified by the NNMi administrator (Communication Configurations SNMP Minimum Security Level settings).
  7. When all else fails, NNMi retains the last known Management Address (if any) and automatically changes the State of that SNMP Agent object to Critical.

This process is repeated during each Spiral Discovery cycle, and the Management Address can change. For example, NNMi's inventory of addresses for the node expands, or the current Management Address does not respond to SNMP queries due to network problems or node reconfiguration. The NNMi administrator can prevent changes to the management address using the Communication Configurations Enable SNMP Address Rediscovery  (disabled) or Preferred Management Address setting.

If  disabled, when the current management address (SNMP agent) becomes unreachable, NNMi does not check for other potential management addresses.
Get-Bulk Enabled

Applies only to SNMPv2 or higher. If you have devices in your network environment that have trouble responding to GetBulk commands, you can instruct NNMi to use Get or GetNext instead of GetBulk.

If  enabled, NNMi uses the SNMPv2c GetBulk command to gather information from devices in your network environment.

If  disabled, NNMi uses the SNMP Get or GetNext command to gather information from devices in your network environment (requesting responses for one SNMP OID at a time).
SNMP Timeout

(Seconds:Milliseconds) Maximum 1 millisecond less than a minute: 59 seconds 999 milliseconds.

Time that NNMi waits for a response to an SNMP query before reissuing the request. Both the Discovery Process and the State Poller Service use this setting.

SNMP Retries Count Maximum number of retries that NNMi issues for an SNMP query before determining the query result to be "unresponsive". Zero means no retries. Both the Discovery Process and the State Poller Service use this setting.
SNMP Port Default is 161. Specifies the NNMi management server's port that NNMi uses when generating SNMP traffic. Both the Discovery Process and the State Poller Service use this setting.
SNMP Proxy Address

Optional. IP address of the your SNMP Proxy Server (for example, a proxy that gathers data from non-SNMP devices and can use that data to respond to NNMi SNMP requests).

To enable a proxy, you must also provide the port number of your SNMP Proxy Server. See SNMP Proxy Port (next attribute).

When you configure NNMi to use a Proxy Server, you must ensure that the Proxy Server vendor supports the Object Identifiers used to handle SNMP requests and responses.
SNMP Proxy Port

Optional. Port number of the SNMP Proxy Server.

To enable a proxy, you must also provide the IP address of your SNMP Proxy Server. See SNMP Proxy Address (previous attribute).

When you configure NNMi to use a Proxy Server, you must ensure that the Proxy Server vendor supports the Object Identifiers used to handle SNMP requests and responses.

SNMP Minimum Security Level

This setting determines whether each NNMi Rediscovery cycle automatically detects the best SNMP choice (v1, v2, or v3) for each Node (automatically detects any upgrade to the SNMP agent on each Node), or uses only the SNMP version that you specify.

For SNMPv1 or SNMPv2c, configure NNMi to use Community Strings in your network environment:

  • Community Only (SNMPv1)
    NNMi tries only SNMPv1 settings.
  • Community Only (SNMPv1 or v2c)
    NNMi first tries to use SNMPv2c settings, and, if that fails, NNMi tries SNMPv1 settings.
  • Community
    NNMi first tries to use SNMPv2c settings, and, if that fails, NNMi tries SNMPv1 settings. If both SNMPv2c and SNMPv1 fail, NNMi tries SNMPv3 settings if any are available.

For SNMPv3, configure NNMi to use the User-based Security Module (USM) level of security required in your network environment (if your environment also uses SNMPv1/SNMPv2c, select Community):

  • No Authentication, No Privacy
  • Authentication, No Privacy
  • Authentication, Privacy

NNMi needs to know which SNMPv1 or SNMPv2c community strings (read/write) are used in your environment and which SNMPv3 USM settings are used in your environment.

Management Address Selection Settings
Attribute Description
First Choice

Configure how NNMi chooses the Management Address for Nodes, if possible:

  • Seed IP / Management IP

    NNMi uses the Seed address only during initial Discovery. The Seed address is either the specified IP address or the DNS address associated with the specified hostname.

    Otherwise, NNMi uses the current Management Address.

  • Lowest Loopback IP address (loopback address)
  • Highest Loopback IP address
  • Interface Matching (instead of addresses)
Second Choice Configure how NNMi choose the Management Address for Nodes when the First Choice is not available.
Third Choice Configure how NNMi choose the Management Address for Nodes when the First Choice and Second Choice are not available.
Interface Matching

Optional. When First, Second, or Third Choice is set to Interface Matching, provide the appropriate values for the following SNMP MIB-II attributes.

Provide more than one value by separating each with a comma.

Space characters are permitted within values, but not before or after a comma.

For example, Lo0,My Favorite Interface,Lo1 produces the following results with the spaces “My Favorite Interface”

However, Lo0, My Favorite Interface, Lo1 produces the following results with spaces “ My Favorite Interface” (initial character is a space) and " Lo1" (initial character is a space)

No wildcards or quotes allowed within values:

  • ifIndex values (for example, 4)
  • ifAlias values (for example, Vlan99)
  • ifName values (for example, lo0)
  • ifDescr values (for example, 1000Gbic Port 9/27)

NNMi searches current interface data for an exact match in this order: index, alias, name, and description. If the interface has multiple IP addresses, NNMi begins with the lowest IP address and selects the first match in ascending order.
IP Version Preference

Tip If this attribute does not appear in the Management Address Selection settings box, check the following:

  • Are you using NNMi Advanced (required for IPv6 support)?
  • Did your NNMi Administrator disable NNMi Advanced's IPv6 feature?

IP Version Preference: Select one of the following to influence Spiral Discovery's evaluation of newly discovered nodes. Previously established Management Addresses will not change if you modify this IP Version Preference setting:

  • IPv4
  • IPv6
  • Any (meaning NNMi uses the first address that responds for newly discovered nodes)
Default ICMP Settings
Attribute Description
ICMP Timeout

(Seconds:Milliseconds) Maximum 1 millisecond less than a minute: 59 seconds 999 milliseconds.

Time that NNMi waits for a response to an ICMP query before reissuing the request.

ICMP Retries Count Maximum number of retries that NNMi issues for an ICMP query before logging an error. Zero means no retries.

Timeout / Retry behavior example for SNMP

When NNMi attempts to contact a device, your configuration settings for Timeout and Retry influence NNMi behavior.

NNMi attempts to obtain information about a hostname/IP-address using SNMP, then waits the configured timeout interval for a response. If not successful, NNMi increments the timeout interval before trying again. This process repeats until one of the following is true:

  • The device responds to SNMP.

  • The maximum configured number of SNMP Retries fails. For example, if your timeout is 2 seconds and your retry is 3:

    • NNMi attempts to communicate with a device and waits 2 seconds for a response.
    • If unsuccessful, NNMi retries and waits 4 seconds for a response.
    • If unsuccessful, NNMi retries a second time and waits 6 seconds for a response.
    • If unsuccessful, NNMi retries a third time and waits 8 seconds for a response.

    If no response, NNMi repeats this process using the next configured SNMP level.

  • NNMi exhausts all possibilities. NNMi considers the hostname/IP-address to be a non-SNMP device until the next Discovery or Monitoring cycle.

Tip It is best to use the same timeout/retry numbers for both ICMP and SNMP.

Your choice of SNMP Minimum Security Level determines the range of possibilities:

  • If your SNMP Minimum Security Level is Community Only (SNMPv1), NNMi uses only SNMPv1 to locate SNMP agents.

  • If your SNMP Minimum Security Level is Community Only (SNMPv1 or v2c), NNMi cycles through the following until successful:

    SNMPv2c

    SNMPv1

  • If your SNMP Minimum Security Level is Community, NNMi cycles through the following until successful:

    SNMPv2c

    SNMPv1

    SNMPv3 No Authentication, No Privacy settings (if any matching configurations, otherwise skip).

    SNMPv3 Authentication, No Privacy settings (if any matching configurations, otherwise skip).

    SNMPv3 Authentication, Privacy settings (if any matching configurations).

  • If your SNMP Minimum Security Level is No Authentication, No Privacy, NNMi cycles through the following until successful:

    SNMPv3 No Authentication, No Privacy settings (if any matching configurations at this, otherwise skip)

    SNMPv3 Authentication, No Privacy settings (if any matching configurations, otherwise skip).

    SNMPv3 Authentication, Privacy settings (if any matching configurations).

  • If your SNMP Minimum Security Level is Authentication, No Privacy, NNMi cycles through the following until successful:

    SNMPv3 Authentication, No Privacy settings (if any matching configurations, otherwise skip).

    SNMPv3 Authentication, Privacy settings (if any matching configurations).

  • If your SNMP Minimum Security Level is Authentication, Privacy, NNMi cycles through the following until successful:

    SNMPv3 Authentication, Privacy settings (if any matching configurations). 

Timeout / Retry behavior example for ICMP

When NNMi attempts to contact a device, your configuration settings for Timeout and Retry influence NNMi behavior.

NNMi attempts to contact the device using ICMP, then waits the configured timeout interval for a response. If not successful, NNMi increments the timeout interval before trying again. This process repeats until one of the following is true:

  • The device responds to ICMP.

  • The maximum configured number of ICMP Retries fails. NNMi considers the device unreachable through ICMP until the next Discovery or Monitoring cycle. For example, if your timeout is 2 seconds and your retry is 3:

    • NNMi attempts to communicate with a device and waits 2 seconds for a response.
    • If unsuccessful, NNMi retries and waits 4 seconds for a response.
    • If unsuccessful, NNMi retries a second time and waits 6 seconds for a response.
    • If unsuccessful, NNMi retries a third time and waits 8 seconds for a response.

Tip It is best to use the same timeout/retry numbers for both ICMP and SNMP.

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