9.1 Using the Console's Edit Function

You create a link in the same you way you create elements of other categories. Invoke the Console's graphical editor function (press Edit >> Create in the Console's control area) and click SELECT in the Connection category. See Figure 9-1.

Figure 9-1

You can manage a connection of any type--types link or rs232, the types supplied with SNM, or connection types that you add. You can create a link between any two elements. However, realistically, the most useful links are between two components, such as two routers, or a router and a subnet.

After you click SELECT in the Create button in the window shown in Figure 9-1, you receive a properties window for a new connection as shown in Figure 9-2.

Figure 9-2

Referring to Figure 9-2, Object1 and Object2 are the names of objects in the runtime database. SNM manages the link based on the data returned from Object1. The name of the link (in the Name field) is for your use and cannot be an existing object in the database. For a link, you should have the ping and, if one or both objects support it, the snmp agents checked off.

After you click SELECT on apply your link object is created and is displayed in the Console as shown in Figure 9-3.

Figure 9-3

This example shows the link in the view for the machine, fmtv14a-136, a router that is the first object (Object1) listed in the link properties. This choice of where to locate the object is arbitrary. You might locate the link in its own view, in your Home view, or the view that displays glyphs for both the router and the subnet to which it connects. In the example, we copy the link object to the view displaying the objects connected by the link. See Figure 9-4.

Figure 9-4

In Figure 9-4, note that the link lies between the two objects specified as Object1 and Object2 in Figure 9-2. That is, it connects the router fmtv14a-136 to the subnet umtv-eng-fddi-bb-routers.

Independent of creating the object link_to_fddi_net in the Console, if you are creating the link object "by hand", you must add an entry to the linkmap file to identify the new link. The linkmap file, described in a man page supplied with SNM, is stored by default in the following directory:

• /var/adm/snm for Solaris 1.x
• /var/opt/SUNWconn/snm for Solaris 2.x

For the link object link_to_fddi_net we create the following entry in the linkmap file:

fmtv14a-136 2 link_to_fddi_net

The first field in this entry (fmtv14a-136) corresponds to Object1 in the link properties sheet. As with Object1 in the properties sheet, SNM manages the link based on data returned by the element in this first field. The third field (link_to_fddi_net) corresponds to the Name field in the properties sheet. The second field (2) is the interface on the machine specified in the first field. This is the interface over which the connection exists to the object at the remote end of the link. We obtained this number from the IP Discover Tool, so strictly speaking, we have "cheated" in this example. However, we later describe how to use IP Discover to perform the same tasks that are described here.

At this point, the link is fully manageable. That is, you can send event requests to it and, if the machine identified in the linkmap file is running an SNMP agent, can receive traps from it.

Sending an Event Request to a link is the same as sending such a request to a component. Figure 9-5 is an example of invoking a Send Request to a link.

Figure 9-5

After invoking Send Request, you receive the Request Builder window in Figure 9-6.

Figure 9-6

1. Click SELECT on Event Request.

2. Choose an agent schema and group.

3. Click SELECT on Apply.

You receive an Event Request properties window, such as the one in Figure 9-7.

Figure 9-7

The Key field in the properties sheet is derived from the interface-number field in the linkmap file. The fact that this number displays correctly is one indication of a valid linkmap entry for link_to_fddi_net.

You can use the decay feature to alert you if your link goes down, then comes up again. If the link goes down (with a resultant change of glyph color to red, orange, yellow, or a color you customize) then comes back up, the glyph color changes to blue (or a color you customize) and remains that color until reset or until the link goes down again.

If the link goes down (or decays), you observe the glyph effect in the Console, just as you do for an event occurring for any element. The difference with the link management feature is that the link itself displays your specified glyph effect. When a link changes color, blinks, or dims, it indicates that one or both of the machines at either end of the link is down, or that the link medium itself is disrupted.

9.2 Using IP Discover to Create Manageable Links

The IP Discover Tool automates the process of creating manageable links and adding required entries to the linkmap file. In this example, we "discover" the same link we created by hand in the previous section.

Invoke IP Discover by selecting Tools >> Discover in the Console's control area. In the IP Discover Tool's base window, click SELECT on Configuration Options. In the IP Discover Configuration window, to find manageable links, click SELECT on Yes in Add Object Connections. The window shown in Figure 9-8 has Add Object Connections selected.

Figure 9-8

In addition to the Add Object Connections selection, the non-default selections in the window shown in Figure 9-8 are: Maximum Hops (changed from 0 to 1), Add To All Views (changed from Yes to No), Routers (only) for Objects to Discover. A Viewname of "routers" is specified.

Starting with version 2.3, you can choose the ARP or Ping search method in addition to the default method. The default method is a combination of ARP and Ping. See "Part 2: Reference" for descriptions of these methods.

The effect of the selections shown in Figure 9-8 is to tell IP Discover, "Find only routers 0 or 1 hops away and find all links between those routers. Add all discovered elements to a view named 'routers'."

After clicking SELECT on Apply and starting the IP Discover function, you receive a view similar to the one in Figure 9-9.

Figure 9-9

Double-click on the network icon in Figure 9-9 to receive the sub-view shown Figure 9-10.

Figure 9-10

A difference between the link you created yourself in the previous section and the link created by IP Discover is the name. The IP Discover Tool creates a name by combining the names of the two linked objects and appending the string link. You can illustrate this by pulling down the glyph menu for the link glyph, as shown Figure 9-11.

Figure 9-11

Figure 9-12 shows the properties of the "discovered" link. Note that, except for the name, these properties are identical to the properties for the hand-created link, shown in Figure 9-2 on page 9-3.

Figure 9-12

As with the hand-created link, SNM manages the link based on data returned from the element in the Object1 field. Note that localhost is the default for proxy hosts, so the specification of localhost for the ping and snmp agents is equivalent to the empty proxy fields for ping and snmp shown in Figure 9-2 on page 9-3.

The decision to invoke the Add Object Connections feature in the Discover Tool should be a considered one. While the automatic creation of manageable links might be desirable, there are these disadvantages to consider:

• You lengthen the amount of time IP Discover takes to find elements and build your database. The time required by the monitor function to detect changes in your database is also lengthened proportionately.
• If your network consists of a set of LANs, you create many links that have little or no value from a network management point of view. With Add Object Connections turned on, the IP Discover Tool creates links between each machine on a subnet and that subnet. In effect, you have a link that maps to the machine's network interface and its transceiver cable (in the case of Ethernet). This is of no more value than having an element for the machine (or interface) itself.
• Following from the preceding item, you end up with a much larger database than you would otherwise.

Depending on the number of links you want to manage, it might be better for you to use the Console's graphical editor function, as described in the previous section, than to use IP Discover Tool's Add Object Connections feature.