Cabletron Systems ATX, Справочное руководство

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Chapter 1: Introduction
1-6 ATX MIB Reference Guide
1.6 USER FUNCTIONS
The SNMP primitives may be used to accomplish the following functions:
• Obtain the unit’s current value of certain parameters - the NMS uses the
GetRequest or GetNextRequest PDU, and the unit responds with a
GetResponse PDU. If the NMS issues a GetRequest for an unsupported
parameter, the unit sends a GetResponse with a noSuchName
ErrorStatus
1
.
If the NMS issues a GetNextRequest for an unsupported parameter, the unit
skips to the next object.
• Change the unit’s value of certain parameters - the NMS uses the SetRequest
PDU, and the unit responds with a GetResponse PDU. The unit will change
both its current value and its local default to be used when the unit reboots,
unless noted otherwise.
• Obtain the current value of certain parameters and simultaneously change the
value of other parameters - the NMS uses the SetRequest PDU, and the init
responds with a GetResponse PDU. For the parameters which are being
obtained rather than changed, the NMS must use the ASN.1 NULL value with
the SetRequest PDU.
• Provide notification of significant events - the unit uses the Trap PDU.
The unit implements two non-standard features with respect to the SNMP
SetRequest:
• The variable bindings within a SetRequest are sometimes processed
sequentially rather than simultaneously. For example, if a SetRequest
contains two parameters with an incorrect value specified for the second
parameter, the unit returns a badValue error to the NMS; however, the unit
may have updated its value for the first parameter.
• The values within the variable bindings of the returned GetResponse may
reflect meaningful information, rather than being an exact copy of the values
from the SetRequest. For example, if a SetRequest contains two variable
bindings, the first specifying that memory should be examined and the second
specifying the contents of the memory, then the unit’s GetResponse will
update the value of the second variable binding to contain the actual contents
of the memory.
1.
If implementing the parameter is required, it might seem more reasonable to return a
GetResponse with no error and the ASN.1 NULL value as the parameter’s value; however,
leading authorities such as Marshall T. Rose (author of
The Simple Book ) suggest that
noSuchName be returned, because many existing SNMP management stations do not
handle NULL values correctly.