Cisco CNS Network Registrar User's Guide, 5.0
Appendix F - SNMP Notification
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Appendix F - SNMP NotificationAppendix F - SNMP Notification
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SNMP Notification

SNMP Notification

The Network Registrar Simple Network Management Protocol (SNMP) notification support allows you to be warned of error conditions and possible problems with the Network Registrar DNS and DHCP servers, and to monitor threshold conditions that may indicate failure or impending failure conditions.

How Notification Works

Network Registrar SNMP notification support allows a standard SNMP management station to receive notification messages from the two servers. These messages contain the details of the event that triggered the SNMP trap.

Network Registrar generates notifications in response to predetermined events that are detected and signaled by the application code. In addition to the knowledge that a particular event occurred, each event can also carry with it a particular set of parameters or current values. For example, the free-address-low-threshold event may occur within the FDDI-Devices scope with a value of 10 percent free. Other scopes and values are also possible for such an event and each type of event may have different parameters associated with it.

Table F-1 describes the events that can generate notifications.


Table F-1: Notification Events
Event Description

Address conflict with another DHCP server detected

Generates a notification when an address conflict with another DHCP server is detected.

Configuration mismatch

Indicates a configuration mismatch between DHCP failover main and backup servers.

DNS queue becomes full

Generates a notification when the DHCP server's DNS queue fills and the DHCP server stops processing requests. This is a rare internal condition.

Duplicate IP address detected

Generates a notification whenever a duplicate IP address is detected.

Change in free address count

Generates a free-address-low trap when the number of free IP addresses become less than or equal to the low threshold. Generates a free-address-high trap when the number of free IP addresses exceeds the high threshold.

Other server not responding

Generates a notification when another server ((DHCP, DNS, or LDAP) stops responding to the DHCP server.

Other server responding

Generates a notification when another server (DHCP, DNS, or LDAP) responds after having been unresponsive.

Server start

Generates a notification whenever the DHCP or DNS server is started or re-initialized.

Server stop

Generates a notification whenever the DHCP or DNS server is stopped.


Handling Notification Events

When Network Registrar generates a notification, a single copy of the notification is transmitted as an SNMP Trap Protocol Data Unit (PDU) to each recipient. The list of recipients and other notification configuration information are shared by all events (and scopes) and are read when the server is initialized.

You configure notifications through the Network Registrar CLI interface using the trap command. The notification configuration information is persistent and is re-initialized when you run the server reload command on the respective server. For more information about configuring notifications, see the trap command in the Network Registrar CLI Reference Guide.

To use SNMP notifications on your system, you must specify trap recipients. These recipients indicate where Network Registrar notifications are directed. By default, all notifications are enabled, but no trap recipients are defined. Until you define the recipients, no notifications are sent. For more information about adding recipients, see the trap addRecipient command in the Network Registrar CLI Reference Guide.

Network Registrar implements SNMP Trap PDUs according to the SNMP v1 standard. Each trap PDU contains:

  • A generic-notification code of enterprise-specific.

  • The specific-notification field contains a code indicating the event or threshold crossing that has occurred.

  • The variable-bindings field contains additional information about certain events.

Refer to the Management Information Base (MIB) for the details. You can find the MIB in the following locations based on the platform.

UNIX
/opt/nwreg2/misc/CISCO-NETWORK-REGISTRAR-MIB.my
Windows/NT
\ProgramFiles\Network Registrar\Misc\Cisco-NETWORK-REGISTRAR-MIB.my