SNMP Manager Programmer's Guide

Constructing and Interpreting Packets
SNMP Manager Programmer’s Guide–134249
5-4
Trap Packets
Trap Packets
Figure 5-3 illustrates the fields in a trap packet. The PDU type identifies the PDU as a
Trap PDU. The enterprise field is an OID identifying the trap originator. The address
is the IP address of the trap originator. The generic-trap and specific-trap fields are
integers that characterize the trap.
Table 5-3
summarizes how the values of most of the fields are set. Setting variable
bindings is the topic of Variable Bindings on page 5-5.
Figure 5-3. The Trap Packet
Table 5-3. Assigning Trap Packet Values
Packet
Field
Assigned
Value By Value Description
SNMP_PKT_T
Field
PDU type Manager
Services
The value 4, defined as TRAP_PDU, is
assigned.
pdu_type
enterprise SNMP_Create
_Trap(), agent,
or subagent
An OID describing the SNMP subtree
associated with the trap originator.
pdu.trap_pdu.
enterprise_objid.
component-list
address SNMP_Create
_Trap(), agent,
or subagent
The IP address at which the trap
originator resides.
pdu.trap_pdu.
net_address
generic-trap SNMP_Create
_Trap(), agent,
or subagent
An integer describing one of the
standard generic trap types:
0 (coldStart)
1 (warmStart)
2 (linkDown)
3 (linkUp)
4 (authenticationFailure)
5 (egpNeighborLoss)
6 (enterpriseSpecific)
pdu.trap_pdu.
generic_trap
specific-trap SNMP_Create
_Trap(), agent,
or subagent
An enterprise-defined integer
characterizing the trap.
pdu.trap_pdu.
specific_trap
time-stamp SNMP_Create
_Trap(), agent,
or subagent
The time at which the trap was issued,
usually the number of timeticks
(1/100ths of a second) since the
originating entity’s system was last
started.
pdu.trap_pdu.
trap_time_ticks
502
PDU type variable bindingsenterprise address
generic-
trap
specific-
trap
time-stamp