SNMP Monitor

The SiteScope SNMP Monitor reads a value from an SNMP device. Many network devices support the SNMP protocol as a way of monitoring them. You will need to know the OID's (Object ID's) for the device you want to monitor. These may be available in the product documentation or in the form of a MIB file.

Note: To have SiteScope listen for SNMP traps from multiple devices, use the SNMP Trap Monitor.

Usage Guidelines

Use the SNMP Monitor to monitor devices that communicate with the SNMP protocol, such as firewalls, routers and UPS's. Several operating systems suppliers also provide SNMP agents and Management Information Bases (MIBs) for accessing workstation or server performance metrics, interface statistics, and process tables via SNMP.

You can use the SNMP Monitor to watch any values known by the SNMP agent running on a device provided you can supply an OID that maps to that value. If your router supports SNMP, for example, you could have SiteScope monitor for packet errors, bandwidth, or device status.

Requirements for using the SNMP Monitor include:

SNMP agents must be deployed and running on the servers and devices that you want to monitor
The SNMP agents must be supplied with the necessary Management Information Bases (MIBs) and configured to read those MIBs
You need to know the Object ID's (OIDs) of the parameters you want to monitor.

In some cases, an equipment manufacturer may supply a list of OID's that are available. Otherwise, you may need to locate a MIB browser utility in order to "walk" a MIB and extract the values of interest to you.

Completing the SNMP Monitor Form

To display the SNMP Monitor Form, either click the Edit link for an existing SNMP Monitor in a monitor table, or click the Add a new Monitor to this Group link on a group's detail page and click the Add SNMP Monitor link.

Complete the items on the SNMP Monitor form as follows. When the required items are complete, click the Add Monitor button.

Host Name

Enter the host name or IP address of the SNMP device that you want to monitor (for example, demo.thiscompany.com). By default, this will connect to port 161. If your SNMP device is using a different port, add it to the hostname using ":port". For example, to use port 170, you would enter demo.sitescope.com:170.

Object ID

Select the Object ID mnemonic from the drop-down list or enter the Object Identifier (OID) for the SNMP value you want to retrieve. The OID specifies which value should be retrieved from the device. (for example, 1.3.6.1.2.1.4.3). To troubleshooting basic connectivity to the device and to confirm that the SNMP agent is active, select the system.sysDescr object from the drop-down list if other objects can not be found.

Note: SiteScope version 7.1 and later supports SNMP version 1 and version 2. In order to send a trap using snmpv2, you must select the version number in the Advanced Options section.

If you receive the error message "There is no such variable name in this MIB", it means SiteScope was able to contact the device but the OID given is not know by the device. You need to provide an OID that is valid to the device in order to obtain a value.

If you have a MIB file for the device you want to monitor, you can copy the *.mib (or *.my) file into the <SiteScope install path>/SiteScope/templates.mib subdirectory and use the MIB Help utility to compile the MIB and browse the OID's for the device. Click the MIB Help hyperlink to bring up the MIB Helper. Select the MIB file to browse using the drop-down list. Click the List OIDs button to show the OID's from the select MIB file

Note: it is not necessary to browse a MIB file with the SiteScope Mib Helper in order to monitor a device. The MIB Helper is provided simply as a tool to help you discover OID's available on a device, but it is not the only tool available.

You can also check the on-line Knowledge Base avialable via the Cusotmer Support site for other information relating to monitoring SNMP systems. Also note that not all MIB files can be browsed by the MIB Helper: the Mib Helper only supports MIB files that are version SNMP v1.

Index

The index of the SNMP object. Values for an OID come as either scalar or indexed (array or table) values. For a scalar OID, the index value must be set to 0. For an indexed or table value, you must provide the index (a positive integer) to the element that contains the value you want. For example, the OID 1.3.6.1.2.1.2.2.1.17 is an indexed value that contains four elements. To access this second element of this OID you enter an index of 2 in the Index text box. To access the fourth element, enter an Index value of 4.

In some vendor specific MIB's, the indexed entries (often refered to in tables) can have compound index values. For example, the OID for the process entry table in a Sun MicroSystems server MIB may be: .1.3.6.1.4.1.42.3.12.1.1. This indexed or table object may have up to eleven nodes with OIDs ranging from .1.3.6.1.4.1.42.3.12.1.1.1 to .1.3.6.1.4.1.42.3.12.1.1.11. Each of these nodes contains an indexed list of entries with index values that range from 0 to over 27300 where the Index value represents the process ID number used by the operating system (view examples using the ps -ef command in UNIX). In this example, the index values may not be consecutive from 0 to 27300.

Community

Enter the Community string for the SNMP device. The Community string provides a level of security for a SNMP device. Most devices use "public" as a community string. However, the device you are going to monitor may require a different Community string in order to access it. You will have to find out if the device requires different string and supply it in this text box.

Update every

Select how often the monitor should check this SNMP value. The default interval is to run or update the monitor once every 10 minutes. Use the drop-down list to the right of the text box to specify another update interval in increments of seconds, minutes, hours, or days. The update interval must be 15 seconds or longer.

Title

Enter a title text for this monitor. This text is displayed in the group detail page, in report titles, and other places in the SiteScope interface. If you do not enter a title text, SiteScope will create a title based on the host, server, or URL being monitored.

You can also check the on-line Knowledge Base avialable via the Cusotmer Support site for other information relating to monitoring SNMP systems.

Advanced Options

The Advanced Options section presents a number of ways to customize monitor behavior and display. Use this section to customize error and warning thresholds, disable the monitor, set monitor-to-monitor dependencies, customize display options, and enter other monitor specific settings required for special infrastructure environments. The options for this monitor type are described below. Complete the entries as needed and click the Add or Update button to save the settings.

Disable

Check this box to temporarily disable this monitor and any associated alerts. To enable the monitor again, clear the box.

SNMP Version (V1 or V2)

Select the SNMP version used by the SNMP host you want to monitor. SiteScope supports both SNMP version 1 and version 2.

Timeout

Enter the total number of seconds SiteScope should wait for a successful reply.

Retry Delay

Enter the number of seconds SiteScope should wait before retrying the request. By default SiteScope will wait one second. It will continue to retry at the interval specified here until the Timeout threshold is met.

Scaling

If you choose a scaling option from the scaling drop-down list, SiteScope will divide the returned value by this factor before displaying it. Alternatively, you may specify a factor by which the value should be divided in the text box to the right of the drop-down list.

Match Content

Use this item to match against an SNMP value, using a string or a regular expression or XML names.

Units

Enter an optional units string to append when displaying the value of this counter.

Measurement Label

Enter an optional text string to describe the measurement being made by the monitor.

Measure as Delta

Click this box to have SiteScope report the measurement as the difference between the current value and the previous value.

Measure as Rate per Second

Click this box to have SiteScope divide the measurement by the number of seconds since the last measurement.

Percentage Base

Enter a number or SNMP object ID in this box. If entered, the measurement will be divided by this value to calculate a percentage. If an object ID if entered the Index from above will be used

Measure Base as Delta

Check this box to have SiteScope calculate the Percentage Base as the difference between the current base and the previous base. Use this option when an SNMP object ID is used for Percentage Base and the object is not a fixed value.

Gauge Maximum

Enter a maximum value that should be used to create the SiteScope gauge display for this object ID.

SNMP V3 Username

If you are using SNMP version 3, enter the username to be used for authentication. Note: SiteScope only supports MD5 authentication for SNMP V3.

SNMP V3 Password

If you are using SNMP version 3, enter the password to be used for authentication for SNMP V3. Note: SiteScope only supports MD5 authentication for SNMP V3.

Verify Error

Check this box if you want SiteScope to automatically run this monitor again if it detects an error. When an error is detected, the monitor will immediately be scheduled to run again once.

Note: In order to change the run frequency of this monitor when an error is detected, use the Update every (on errors) option below.

Note: The status returned by the Verify Error run of the monitor will replace the status of the originally scheduled run that detected an error. This may cause the loss of important performance data if the data from the verify run is different than the initial error status.

Warning: Use of this option across many monitor instances may result in significant monitoring delays in the case that multiple monitors are rescheduled to verify errors at the same time.

Update Every (on error)

You use this option to set a new monitoring interval for monitors that have registered an error condition. For example, you may want SiteScope to monitor this item every 10 minutes normally, but as often as every 2 minutes if an error has been detected. Note that this increased scheduling will also affect the number of alerts generated by this monitor.

Schedule

By default, SiteScope monitors are enabled every day of the week. You may, however, schedule your monitors to run only on certain days or on a fixed schedule. Click the Edit schedule link to create or edit a monitor schedule. For more information about working with monitor schedules, see the section on Schedule Preferences for Monitoring.

Monitor Description

Enter additional information about this monitor. The Monitor Description can include HTML tags such as the <BR> <HR>, and <B> tags to control display format and style. The description will appear on the Monitor Detail page.

Report Description

Enter an optional description for this monitor that will make it easier to understand what the monitor does. For example, network traffic or main server response time. This description will be displayed on with each bar chart and graph in Management Reports and appended to the tool-tip displayed when you pass the mouse cursor over the status icon for this monitor on the monitor detail page.

Depends On

To make the running of this monitor dependent on the status of another monitor or monitor group, use the drop-down list to select the monitor on which this monitor is dependent. Select None to remove any dependency.

Depends Condition

If you choose to make the running of this monitor dependent on the status of another monitor, select the status condition that the other monitor or monitor group should have in order for the current monitor to run normally. The current monitor will be run normally as long as the monitor on which it depends reports the condition selected in this option.

List Order

By default, new monitors are listed last on the Monitor Detail page. You may use this drop-down list to choose a different placement for this monitor.

Error if

By default, SiteScope generates an error if the returned status is anything other than 'ok'. You may choose to have SiteScope generate an error based on the SNMP value returned. Enter a comparison value and use the comparison operator list to specify an error threshold such as: >= (greater than or equal to), != (not equal to), or < (less than).

Warning if

By default, SiteScope does not generate warnings for SNMP monitors. You may choose to have SiteScope generate an error based on the SNMP value returned.

Good if

SiteScope reports a good status if the reading returned is "OK". You can change this to be based upon a specific value or a content match.