D-Link DES-3550 User Manual page 30

DES-3550 Layer 2
network devices. Use SNMP to configure system features for proper operation, monitor
performance, and detect potential problems in the Switch, switch group, or network.
Managed devices that support SNMP include software (referred to as an agent), which runs
locally on the device. A defined set of variables (managed objects) is maintained by the
SNMP agent and used to manage the device. These objects are defined in a Management
Information Base (MIB), which provides a standard presentation of the information controlled
by the on-board SNMP agent. SNMP defines both the format of the MIB specifications and
the protocol used to access this information over the network.
The DES-3550 supports SNMP versions 1, 2c, and 3. You can specify which version of
SNMP you want to use to monitor and control the Switch. The three versions of SNMP vary
in the level of security provided between the management station and the network device.
In SNMP v.1 and v.2, user authentication is accomplished using 'community strings', which
function like passwords. The remote user SNMP application and the Switch SNMP must use
the same community string. SNMP packets from any station that has not been authenticated
are ignored (dropped).
The default community strings for the Switch used for SNMP v.1 and v.2 management access
are:
public - Allows authorized management stations to retrieve MIB objects.
private - Allows authorized management stations to retrieve and modify MIB objects.
SNMP V3 uses a more sophisticated authentication process that is separated into two parts.
The first part is to maintain a list of users and their attributes that are allowed to act as SNMP
managers. The second part describes what each user on that list can do as an SNMP manager.
The Switch allows groups of users to be listed and configured with a shared set of privileges.
The SNMP version may also be set for a listed group of SNMP managers. Thus, you may
create a group of SNMP managers that are allowed to view read-only information or receive
traps using SNMP v.1 while assigning a higher level of security to another group, granting
read/write privileges using SNMP v.3.
Using SNMP v.3 individual users or groups of SNMP managers can be allowed to perform or
be restricted from performing specific SNMP management functions. The functions allowed
or restricted are defined using the Object Identifier (OID) associated with a specific MIB. An
additional layer of security is available for SNMP v.3 in that SNMP messages may be
encrypted. To read more about how to configure SNMP v.3 settings for the Switch read the
section entitled Management.
Traps
Traps are messages that alert network personnel of events that occur on the Switch. The
events can be as serious as a reboot (someone accidentally turned OFF the Switch), or less
serious like a port status change. The Switch generates traps and sends them to the trap
recipient (or network manager). Typical traps include trap messages for Authentication
Failure, Topology Change, and Broadcast\Multicast Storm.
Fast Ethernet Switch User's Guide
30