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Alarm Configuration
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 to set your alarm.
NOTE |
If you wish to set an alarm on an object whose instance is
table index.length(in bytes).instance(in decimal format)
For the Þrst byte of the instance, you must use the index number of the table which contains the OID you want to track. For example, to set an alarm on an object in the Host Table, deÞne the Þrst byte of the instance as the index number assigned to the speciÞc Host Table you want to check. These index numbers are assigned automatically as the table entries are created; no two tables Ñ even if they are on different interfaces Ñ will share the same table index number.
Second, you must specify the length, in bytes, of the index you will be using. Again, in the case of an object in the Host Table, that value would be 6, since Host Table entries are indexed by MAC address Ñ a
Finally, you must specify the index itself, in decimal format. In the case of a MAC address, that means you must convert the standard hexadecimal format to decimal format. To do this, simply multiply the Þrst digit of the
So, for example, the instance for an object in the Hosts group might read as follows:
2.6.0.0.29.170.35.201
where 2=the host table index; 6=the length in bytes of the index to follow; and 0.0.29.170.35.201=the decimal format for MAC address
For objects with multiple indices Ñ such as objects in a matrix table Ñ you must add additional length and index information to the instance deÞnition, as illustrated below:
3.6.0.0.29.170.35.201.6.0.0.29.10.20.183
where 3=the matrix table index; 6=the length in bytes of the index to follow; 0.0.29.170.35.201=the decimal format for MAC address
Additional instance issues may exist for FDDI objects; if youÕre unsure how to assign an instance, use the MIBTree utility to query the object of interest, and note the appropriate instancing on the returned values.
Advanced Alarm Configuration |