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It is useful to monitor network resources from a central point, especially if you want to be alerted when the network performs certain functions or reaches specific utilization levels. For example, you may want to be alerted if router utilization exceeds a certain point, if a host stops responding, or if disk space on your server falls below a certain level.
However, remotely monitoring critical network resources has traditionally been difficult because polling the resource from the network manager occupies excessive bandwidth and ties up valuable network resources (Figure 8-1). The TrafficDirector Resource Monitor uses proxy resources to solve this problem, as this chapter explains.
The TrafficDirector Resource Monitor lets you select and monitor network resources without tying up the network. Used with single-agent, single-domain situations, Resource Monitor combines both DomainView and remote SNMP management into one easy-to-use tool.
This tool lets you use proxy resources to actively manage all critical resources at a remote site, including private MIBs, which eliminates regular polling between a management station and an agent. The result is that the agent polls the resource, so that polling is limited to the segment and does not tie up the network.
Resource Monitor gives you two types of proxy resources to use. Depending on what you want to monitor, you will choose from:
| Proxy SNMP get | This proxy type identifies and collects data on a specific MIB variable on the resource (even if it is a private MIB). For example, you might want to specify a server's disk space MIB for monitoring and Trap Management to be sure you are notified if disk space exceeds a certain point. |
| Proxy IP Ping | This proxy type pings a resource to ensure that it is alive on the network. You will also want to use Trap Manager with this proxy type. |
The real key to the Resource Monitor flexibility and ease-of-use is how it uses proxy resources. You can assign a proxy SNMP get to any SNMP-based network device, such as a server, switch, or bridge. When you do so, the SwitchProbe device attached to the network segment can collect specific data from the device. The SwitchProbe device stores the collected data internally, and TrafficDirector retrieves it when needed (Figure 8-2). Typically, you want to use Trap Manager to set up threshold conditions for the data so that you are notified when the resource is in trouble.
For example, suppose you want to monitor available disk space on a server. First, use Resource Monitor to create a proxy SNMP get on the agent to read the MIB variable for server disk space. (This assumes that the MIB on the agent you use has a variable that reads this value.) Then select a host so that the agent knows which resource you are targeting. You can now use Trap Manager to create a trap to trigger an alarm when the disk space variable falls below a predetermined value.
The agent polls the resource at the interval you specified when you set up the proxy resource and triggers an alarm when the disk space falls below the specified threshold.
When using the proxy IP Ping, you can specify that an agent pings a resource at certain intervals to ensure that it is alive on the segment. Using Trap Manager, you can specify that you are notified if the proxy ping cannot be completed.
It is easy to use Resource Monitor to install new proxy resources or view or delete existing proxy resources at an agent. In this section are the procedures you will use to work with Resource Monitor.
There are two types of proxy resources: SNMP get and IP Ping. The resources that are displayed in the Resource Monitor list, as well as the resources you add, view, or delete, reflect the type of resource you select. The default selection is SNMP. To use the Resource Monitor to install either type of proxy resource on a specific agent, use the following procedure.
Step 1 Select the agent from the list in the TrafficDirector main window and click Resource Monitor. The SNMP Resource Monitor window is displayed (Figure 8-3). Note that the selected agent is displayed at the top of the window.
Step 2 Select Type from the menu bar, and click either SNMP or IP Ping. If you select IP Ping, the IP Resource Monitor window is displayed (Figure 8-4).
The Resource Monitor list contains several headings with values shown below. The list you see depends on whether you selected Type>SNMP or Type>IP Ping from the menu bar. The following list describes the Resource Monitor window (Figure 8-3) for SNMP types:
The following list describes the Resource Monitor window (Figure 8-4) for IP Ping types:
You can select the time interval, which is how long the proxy resource waits before updating TrafficDirector. The range is from 15 seconds to 5 minutes. The default is 1 minute. To select the sample interval, use the following procedure.
Step 1 Select Sample from the menu bar.
Step 2 Click the sample interval you want.
You add an SNMP get proxy resource when you want to monitor a selected MIB variable on a network resource. The proxy resource returns the value of that variable at each polling interval, and any associated errors. To add a new SNMP get proxy resource at an agent, use the following procedure.
Step 1 Select the agent you want from the list in the TrafficDirector window and click Resource Monitor. The SNMP Resource Monitor window is displayed (Figure 8-3). Note that the selected agent is displayed at the top of the window.
Step 2 Select Type>SNMP from the menu bar. All currently installed SNMP resources for the agent you selected are displayed in the list.
Step 3 Click the Add button to display the Add SNMP Resource window (Figure 8-5).
Step 4 In the Host field, enter the name or IP address of the host you want the agent to monitor.
Step 5 The MIB list displays a list of MIBs for the agent you selected. Do one of the following:
When you select a MIB, TrafficDirector fills in both the Community and the Poll Interval fields, as well as the Variable Name and OID list. The following list describes these fields:
| Community | Describes a string identifier for the SNMP host you want to monitor. Set this field to the value for the host you want. The default value is public. |
| Poll Interval | Describes the number of seconds you specify between samples. The allowed range is a decimal integer from 1 to 65535 seconds. The default is 60 seconds. |
| Variables | Describes the various MIB variables that you can select and monitor with the new proxy resource. Keep in mind that the variable you select must be one with an integer value; text value variables cannot be evaluated and cause errors. Variables are specific to each MIB and are published with the MIB's information. Consult the MIB information manual to select the correct variable. The Variable OID is the object identifier for the object, defined by the variable's location in the SNMP MIB hierarchy. |
Step 6 When the MIB you want to use for an SNMP device is not shown in the MIB list, copy the MIB file you want into the $NSHOME/usr directory. Once you do so, the filename is displayed in the MIB list; now you can go back to Step 5.
Step 7 Highlight the Variable Name and OID you want from the list, and click the Select button.
Step 8 Enter the correct value in the Variable Instance field. This must be a decimal number and must match the value given in your MIB data.
Step 9 Click OK to add the new proxy resource or Cancel to return to the Resource Monitor window. TrafficDirector lists the new proxy resource in the list on the Resource Monitor main window.
An IP ping proxy resource pings the resource and tells you if it responds. When associated with a condition you set in Trap Manager, this provides an effective way of periodically checking critical network resources and receiving automatic notification if a resource goes down. To add a new IP ping proxy resource at an agent, use the following procedure.
Step 1 Select the agent you want from the list in the TrafficDirector window and click Resource Monitor. The Resource Monitor window is displayed (Figure 8-3). Note that the selected agent is displayed at the top of the window.
Step 2 Select Type>IP Ping from the menu bar. All current IP ping resources are displayed in the list for the selected agent.
Step 3 Click the Add button to display the Add IP Ping Resource window (Figure 8-6).
Step 4 In the Host field, enter either the IP address or the name of the host for this resource.
Step 5 In the Ping Interval field, enter the number of seconds you want to use as an interval between pings. The range is a decimal integer from 1 to 3600, with a default of 60.
Step 6 Click OK to install the new proxy resource or Cancel to return to the Resource Monitor window. The resource is listed with the selected agent in the list on the Resource Monitor window.
You may want to view a summary of all the values associated with a resource. This includes the values you enter when you define the proxy resource and the values that are displayed for the resource in the Resource Monitor window. To view a resource in detail, use the following procedure.
Step 1 Select the agent you want from the list in the TrafficDirector window and click Resource Monitor. The Resource Monitor window is displayed (Figure 8-3). Note that the selected agent is displayed at the top of the window.
Step 2 Select either Type>SNMP or Type>IP Ping from the menu bar, depending on the type of resource you want to see. All existing resources of that type you chose for the selected agent are displayed in the list.
Step 3 From the list, select the resource you want to see in more detail.
Step 4 When you click View, the display depends on the type of resource you have selected:
Step 5 When you are finished viewing the information on the window, click OK to return to the Resource Monitor window.
When you no longer need to poll a certain variable, it is a good idea to delete the proxy resource associated with it to conserve agent resources. To delete a proxy resource, use the following procedure.
Step 1 Select the agent you want from the list in the TrafficDirector window and click Resource Monitor. The Resource Monitor window is displayed (Figure 8-3). Note that the selected agent is displayed at the top of the window.
Step 2 Highlight the resource you want to delete in the list in the Resource Monitor window.
Step 3 Select Delete. A cautionary window displays, prompting you to confirm that you want to delete the resource.
Step 4 Click OK to delete the resource or Cancel to return to the Resource Monitor window.
Using Resource Monitor, you can directly see a description of the selected agent's system information (includes location, description, and how long the agent's been up and running) and interface configuration (includes physical address, type, description, network speed, and status). To view agent information, use the following procedure.
Step 1 Select Tools>Agent Info from the menu bar. The Agent Information window is displayed (Figure 8-9).
Step 2 Click OK when you are finished viewing the agent information.
You can print the data contained in the Resource Monitor window at any time. To do so, use the following procedure.
Step 1 Select File>Print from the menu bar. The Print Options window is displayed (Figure 8-10).
Step 2 Do one of the following:
Step 3 Click Apply.
To exit Resource Monitor at any time, select File>Exit from the menu bar.
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