Enterasys Networks 700 - Manual (Page 134)

Alarm Configuration
4-18 Advanced Alarm Configuration
6. In the Alarm Interval field, enter the amount of time over which the selected
variable will be sampled. At the end of the interval, the sample value will be
compared to both the rising and falling thresholds. There is no practical limit to
the size of the interval (as the maximum value is 24,855 days 3 hours 14
minutes and 7 seconds — over 68 years!); the default value is 1 minute.
NOTE
If you wish to set an alarm on an object whose instance is non-integral — for example, a
Host Table object indexed by MAC address — or on an object with multiple indices, like a
Matrix Table entry (which is indexed by a pair of MAC addresses), you must follow
certain special procedures for defining the instance. For these OIDs, the instance
definition must take the following format:
table index.length(in bytes).instance(in decimal format)
For the first 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, define the first byte of the instance as the index number assigned to the specific Host
Table you want to check. These index numbers are assigned automatically as the table
entries are created; no two tables — even if they are on different interfaces — 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 — a six-byte value.
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 first digit of the two-digit hex number by 16, then add the
value of the second digit. (For hex values represented by alphabetical characters,
remember that a=10, b=11, c=12, d=13, e=14, and f=15.) A hex value of b7, for instance,
is represented in decimal format as 16 x 11 + 7, or 183.
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 00-00-1d-aa-23-c9.
For objects with multiple indices — such as objects in a matrix table — you must add
additional length and index information to the instance definition, 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 00-00-1d-aa-23-c9; 6=the length
in bytes of the next index; and 0.0.29.10.20.183=the decimal format for MAC address
00-00-1d-0a-14-b7.
Additional instance issues may exist for FDDI objects; if you’re unsure how to assign an
instance, use the MIB Tools utility to query the object of interest, and note the appropriate
instancing on the returned values.