SNMP Support on Enterasys Switches
Fixed Switch Configuration Guide 12-3
Trap Versus Inform Messages
As compared to earlier versions, SNMPv3 provides a higher degree of reliability for notifying
management stations when critical events occur. Traditionally, SNMP agents communicated
events to SNMP managers via “traps.” However, if a temporary network problem prevented the
manager from receiving the trap, then the trap would be lost. SNMPv3 provides “informs”, which
are a more reliable form of traps. The SNMP agent initiates the inform process by sending an
inform request to the manager. The manager responds to the inform request to acknowledge
receipt of the message. If the inform is not received by the manager, the inform request will
timeout and a new inform request will be sent. Subsequent inform requests will be sent as
previous requests time-out until either an acknowledgement is received from the manager, or
until a pre-specified retry-count is reached.
Access to MIB Objects
SNMP uses the following authentication methods to grant user access to MIB objects and
functions.
Community Name Strings
Earlier SNMP versions (v1 and v2c) rely on community name strings for authentication. In order
for the network management station (NMS) to access the switch, the community string definitions
on the NMS must match at least one of the three community string definitions on the switch. A
community string can have one of these attributes:
• Read-only (ro)—Gives read access to authorized management stations to all objects in the MIB
except the community strings, but does not allow write access.
• Read-write (rw)—Gives read and write access to authorized management stations to all
objects in the MIB, but does not allow access to the community strings.
User-Based
SNMPv3 provides a User-Based Security Model (USM) which relies on a user name match for
authenticated access to network management components.
Refer to “Security Models and Levels” on page 12-6 for more information.
SNMP Support on Enterasys Switches
By default, SNMP Version 1 (SNMPv1) is configured on Enterasys switches. The default
configuration includes a single community name - public - which grants read-write access to the
whole MIB tree for both SNMPv1 and SNMPv2c.
get-response Replies to a get-request, get-next-request, and set-request sent by a management
station.
set-request Stores a value in a specific variable.
trap | inform
3
Unsolicited message sent by an SNMP agent to an SNMP manager when an event
has occurred.
1. With this operation, an SNMP manager does not need to know the exact variable name. A sequential search is
performed to find the needed variable from within a table.
2. The get-bulk operation is only supported in SNMPv2c or later.
3. Inform notifications are only supported in SNMPv3.
Table 12-1 SNMP Message Functions (continued)
Operation Function
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