Overview

This event monitor connects to your switches, routers, and other networking gear using SNMP and retrieves bandwidth data which can be used to trigger alerts and generate graphs. It hides all of the ugly details of SNMP and automatically collects the required data for you.

Use Cases

• Monitoring bandwidth on SNMP-enabled devices
• Getting alerts about devices experiencing high levels of traffic

Monitoring Options

SNMP Version

Select the SNMP version that will be used to collect the inventory data. The best version to use will depend on how your network devices have been configured. Most devices support SNMPv1, but some may require SNMPv2 or SNMPv3.

Community

Enter the SNMP community string that will be used to connect. The community string is equivalent to a password. The default community string for read-only access is "public" so use this value if you are unsure of what community string your devices are configured to use. The community string is only required for SNMPv1 and SNMPv2c connections. SNMPv3 uses different authentication parameters.

Port Number

The standard port number for SNMP requests is 161. If your devices have been configured to use a different port, you can specify it here.

Timeout

The timeout tells the event monitor how long to wait for a response. The default value is best for almost all situations, but you can increase or decrease it if you choose.

Retries

Since SNMP runs on UDP, packet delivery and response are not guaranteed. For this reason it is good practice to tell the event monitor to retry one or more times if it does not receive a response.

Username (SNMPv3 Only)

Specify the user name that will be used when connecting to the network device. This is a required value for the SNMPv3 protocol.

Context (SNMPv3 Only)

In rare cases a context string is required to establish the SNMPv3 connection. If required by your devices, enter it here. This value is optional.

Security Level (SNMPv3 Only)

SNMPv3 connections can support both authentication and privacy. Authentication means that a valid passphrase must be supplied or the SNMP unit will not accept the connection. Privacy means that the connection to the SNMP device must be encrypted, otherwise the device will not accept it. Both are optional. If your devices do not require either, select noAuthNoPriv. If you devices require authentication but not privacy, select authNoPriv. If your devices require both authentication and privacy, select authPriv.

Auth. Protocol Level (SNMPv3 Only)

If authNoPriv or authPriv is selected for the security level, you must specify the authentication protocol for the connection. Supported values are MD5, SHA, SHA-224, SHA-256, SHA-384 and SHA-512. Consult the documentation and configuration of your network devices to determine which protocol they support.

Auth. Passphrase (SNMPv3 Only)

Enter the authentication passphrase that your SNMP devices have been configured to accept. This value is required when authNoPriv or authPriv is selected for the security level.

Privacy Protocol (SNMPv3 Only)

If authPriv is selected for the security level, the privacy protocol must be selected. The supported values are DES and AES.

Priv. Passphrase (SNMPv3 Only)

Enter the privacy passphrase that your SNMP devices have been configured to accept. This value is required when authPriv is selected for the security level.

Alert with [Info/Warning/Error/Critical] if the device cannot be contacted by SNMP

Use this option to select how you will be alerted if the network device cannot be contacted or does not respond to SNMP requests.

Alert if the incoming bandwidth on any interface is greater than a specified value

Use this option to select thresholds based on the observed incoming bandwidth rate on each interface.

Alert if the incoming bandwidth on any interface is less than a specified value

Use this option to select thresholds based on the observed incoming bandwidth rate on each interface. `

Alert if the outgoing bandwidth on any interface is greater than a specified value

Use this option to select thresholds based on the observed outgoing bandwidth rate on each interface.

Alert if the outgoing bandwidth on any interface is less than a specified value

Use this option to select thresholds based on the observed outgoing bandwidth rate on each interface.

Alert if the total bandwidth on any interface is greater than a specified value

The total bandwidth rate is the sum of the incoming and outgoing rates. Use this option to select thresholds based on the observed total bandwidth rate on each interface.

Alert if the total bandwidth on any interface is less than a specified value

The total bandwidth rate is the sum of the incoming and outgoing rates. Use this option to select thresholds based on the observed total bandwidth rate on each interface.

Alert if the total switch bandwidth on any interface is greater than a specified value

To calculate the total switch bandwidth rate, the event monitor adds the total bandwidth rate for each interface. This rate provides a good estimate of the total workload that the switch is currently handling. Use this option to select thresholds based on the observed total switch bandwidth rate on each interface.

Alert if the total switch bandwidth on any interface is less than a specified value

This rate provides a good estimate of the total workload that the switch is currently handling. Use this option to select thresholds based on the observed total switch bandwidth rate on each interface.

Formatting Options - Descriptions

Select "Include full interface descriptions" to instruct the event monitor to read the descriptions from the data supplied by the device and use them in all notifications and alerts. Examples include "eth0" and "loopback". Select "Include just the interface index" to tell the event monitor to reference interfaces using their numeric index such as ".1", ".2", etc.

Formatting Options - Data Units

Select either "Bytes per second" or "Bits per second" according to your preference.

Filters

Use the filters option to select which interfaces will be checked. You can choose to monitor all interfaces, all physical interfaces, only specific interfaces, or all interfaces except for a list that you specify. To specify the interfaces to include or ignore, enter their numeric indexes in a list separated by commas. For example, ".1, .2, .9".

Authentication and Security

For SNMPv1 and SNMPv2c, a community string for the device being monitored is required. For SNMPv3, a username and other SNMPv3 parameters are required.

Protocols

Data Points

This event monitor generates the following data points:

Data Point	Description
Total Switch Bandwidth	The total bandwidth of the SNMP device.
Incoming Rate	The incoming rate of bandwidth.
Outgoing Rate	The outgoing rate of bandwidth.
Total Rate	The total rate of bandwidth.

Sample Output

Tutorial

To view the tutorial for this event monitor, click here.