21-01-2013, 04:18 PM
SNMP V2 & V3
SNMP.ppt (Size: 4.27 MB / Downloads: 56)
SNMP V2 Protocol
RFC 3416
3 types of access to management information
Manager–agent request-response
Manager-Manager request-response : different from SNMPV1
Agent-manager unconfirmed
PDU Details (1)
request-id :unique number to each outstanding request to the same agent
error-status: a non-zero value indicates that an exception occurred
error-index: When the error-status field is nonzero, the error-index value identifies the object that caused the error
PDU Details (2)
variable-bindings: this field enables a single operation to be applied to a group of object instances
First element is an OID (Object Identifier)
Second element can be
Value – Value associated with each object instances
unSpecified – a NULL values is used in retrieval requests
NoSuchObject – indicates agent does not implement the object refered this OID
noSuchInstance – indicates that this object instance does not exist for this operation
endOfMibView – indicates an attempt to reference an OID that is beyond the end of the MIB at the agent
GetRequest PDU
Same as SNMPv1, it is different only the way that responses are handled
SNMP v1 operation is atomic
SNMP v2 operation prepares variable binding according to following rules
1 OID not match – value is set to noSuchObject
2 Otherwise, but not accessible for operation – value is set to noSuchInstance
3 Otherwise, value is set to the value of variable
SNMPv2-Trap PDU
The format is different from SNMPv1
It uses the same format as GetRequestPDU
Using variable bindings field to contain
sysUpTime.0
snmpTrapOID.0
- If the OBJECT clause is present in the macro NOTIFICATION-TYPE, each variable and its value are copied to the variable-binding