SNMP Operations

Get

1. Select the "Advanced" tab and configure the SNMP version to '1' and the Read community to "public".
2. Select "Get" from the operations menu.
3. Select the sysDescr variable from the MIB Tree.

The Result Table displays the sysDescr variable information. Repeat this procedure for any MIB variable. For SNMP V2c, repeat the same procedure, substituting '2' in place of '1' in the version configuration. 

As explained earlier, the V2c agent is configured with three Read and Write community defaults. Configure the browser to use any of these communities and try accessing the MIB variables. You should be able to access some of the MIB variables even with the Read Community configured as any of the 'write' community defaults. For GET operations, if the Read or Write community matches, the agent processes the request. For SET operations, the received community names must match any of the 'write' community names. 

For SNMP V3, substitute '3' in place of '1' in the version configuration in the "Advanced" tab. Configure the other user based auth and priv credentials as explained in the "MIB Browsers" section. 

With appropriate credentials, all the MIB variables are accessible. Select any of the MIB variables in the MIB tree and do a GET operation. 

Get_Next 

1. Repeat the process for GET. Select the sysDescr variable from the MIB tree. Select "Get Next" from the operations menu. The result table will display the sysObjectID variable information.
2. Repeat for additional MIB variables to get the information for the corresponding next variable.

3. Set the SNMP MIB Browser version to v1/v2c. Try to access the private MIB variable "snmpv3PvtObject" with OID value as 43.6.1.4.1.17095.6.1. The access should be restricted. Set the verison to V3, configre the credentails, again try a Get_Next operation for the sae variable. The access should be granted.

Get_Bulk 

This operation is supported in SNMP V2c and SNMP V3. Get_Bulk enables the collection of bulk information from the agent with a single request from the manager.

1. Configure the SNMP version to '2' or '3' in the SNMP browser.
2. If version is configured to '2', set the Read Community to 'public' or 'read.'
3. If version is configured to '3', configure the appropriate V3 credentials.
4. Select the sysDescr variable from the MIB tree.
5. Select the Get Bulk operation from the Operations menu.

The result table will display information for 10 MIB variables in a single request (if the Max-Repetitions=10 and Non-Repeaters=0 is configured). These variables are the lexicographical successors of the sysDescr variable. The number of variables that the agent will respond with can be configured in the browser through the menus: "Tools->Options->Non-Repeaters" and "Tools->Options->Max-Repetitions." The Non-Repeaters and Max-Repetitions numbers are extracted by the SNMP agent from the received Get_Bulk request and the number of variables that will be included in the response PDU is calculated. for more information on calculating the number of variables, Non-Repeaters, and Max-Repetitions, refer to RFC 3416. 

Set 

The Set command updates the variable information of the MIB database in the agent. The Set command can be performed only on those variables which are declared as 'READWRITE' in the MIB scripts, and only if the community name matches any one of the 'write' community names configured with the agent.

1. Select the ledD5 variable from the MIB tree.
2. Configure the SNMP version to '1' or '2.' Configure the Write Community to 'public', 'write', or 'private'.
3. If version is configured to '3', configure the appropriate V3 credentials.
4. Select 'Set' from the Operations menu.

The SNMP SET window will pop up. Enter the value for the browser in the OID field. 

A success message will appear. 

A 'Get' operation for the same variable should now return the new 'Set' value for this variable. LED5 on the demo board should now be ON. Repeat the procedure to set LED5 to OFF. LED6 can also be set ON or OFF.

SNMP Server (Agent)