D-Link DGS-1520-28MP Product Manual 2 - Page 34

DGS-1520 Series Gigabit Ethernet Smart Managed Switch Hardware Installation Guide SNMP-based Management The Switch can be managed with an SNMP-compatible console program. The Switch supports Simple Network Management Protocol (SNMP) versions 1, 2c, and 3. An SNMP agent decodes the incoming SNMP messages and responds to requests with MIB objects stored in the database. The SNMP agent updates the MIB objects to generate statistics and counters. Connecting using SNMP In SNMP versions 1 and 2c, user authentication is accomplished using community strings, which function like passwords. The remote user SNMP application and the Switch must use the same community string. SNMP packets from any station that were not authenticated are ignored (dropped). The default community strings for the Switch are: • public - Allows authorized management stations to retrieve MIB objects. • private - Allows authorized management stations to retrieve and modify MIB objects. SNMPv3 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. This SNMP version may also be set for a listed group of SNMP managers. Thus, a group of SNMP managers can be created to view read-only information or receive traps using SNMP version 1, while assigning a higher level of security to another group, granting read/write privileges using SNMP version 3. Using SNMP version 3 individual users or groups of SNMP managers can be allowed to perform or be restricted from performing specific SNMP management functions. The functions that have been allowed or restricted are defined using the Object Identifier (OID) associated with a specific MIB. An additional layer of security is available for SNMP version 3 in that SNMP messages may be encrypted. Traps Traps are messages that are sent by an SNMP-enabled device to the Network Management Station (NMS) and can be used to alert network personnel of events that occur on the Switch. These events can be as serious, like a reboot (someone accidentally turned off the Switch), or less serious like a port status change. The Switch generates traps and sends them to a pre-configured IP address, usually an NMS. Typical traps include trap messages for Authentication Failure and Topology Change. Management Information Base (MIB) A MIB stores management and counter information. The Switch uses the standard MIB-II Management Information Base module. Consequently, values for MIB objects can be retrieved from any SNMP-based network management software. In addition to the standard MIB-II, the Switch also supports its own proprietary enterprise MIB as an extended Management Information Base. The proprietary MIB may also be retrieved by specifying the MIB Object Identifier. MIB values can be either read-only or read-write. 29