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Advanced Alarm Configuration 4-17
Alarm Configuration
in which they reside; for example, if you wish to set an alarm on an object
located in an RMON Statistics table, you can determine the appropriate
instance by noting the index number assigned to the table that is collecting
data on the interface you’re interested in. In the case of the default tables,
index
numbers often mirror
interface
numbers; however, if there are multiple
default tables per interface, or if additional tables have been created, this may
not be true. (Table index numbers are assigned automatically as table entries
are created; no two tables — even those on different interfaces — will share
the same table index number.)
If you have selected an object from a table which is indexed by some other
means — for example, by ring number — you must be sure to assign the
instance accordingly. If you’re not sure how a tabular object is instanced, you
can use the MIB Tools utility (described in the
Tools Guide
) to query the
object; all available instances for the object will be displayed. (Host and matrix
table objects — which are indexed by MAC address — require special
handling; see the Note which follows this step, page 4-18.)
If you have selected an object which is
not
part of a table, you must assign an
instance value of 0.
Be sure you define your instance values carefully; if you neglect to set the
instance correctly, you will receive the “Set failed; ensure variable is readable”
error message when you click the Apply button to set your alarm.
TIP
You can use the MIB Tree display to determine which objects are tabular and which are
not: objects which are part of a table will descend from a blue folder (which will have a
“T” on it, and a name which will almost always include the word “table”); objects which
are not will descend directly from a yellow folder. (There may be one or more yellow
folders in between the blue folder which contains the table and the leaf object you wish to
use; however, those objects are still part of the table.)