SNMP Configuration

With the SNMP Configuration page, you can:

Note: Some community strings are propagated by the command switch when a member switch joins the cluster. For details, see Propagated Community Strings.

The command switch receives SNMP requests from the SNMP management station and determines whether the request is for itself or for a member switch. If the request is for itself, the SNMP agent on the command switch processes and responds to the request. If the request is for a member switch, the command switch redirects the request to the specified member. The SNMP agent on the member switch processes the request and sends a response to the requester (the command switch), which transmits the response to the original requester (the management station).

When a switch joins a cluster, the command switch adds two community strings--passwords to authenticate SNMP messages--on the member switch. The command switch uses these strings to route SNMP packets to the member switch. If a member switch has no IP address, the command switch also receives SNMP traps--system alerts sent by a member switch--and relays them to the trap manager.

Disabling or Enabling SNMP

Note: Disabling the SNMP agent prevents SNMP applications from accessing the cluster. As a result, you cannot generate reports, which requires SNMP to be enabled with the community string set to "public."

To disable SNMP (enabled by default):

  1. Deselect the Enable SNMP checkbox.
  2. Click Apply.
    The SNMP options, community strings, and trap manager information on the SNMP page is no longer displayed until you reenable SNMP.

To reenable SNMP, select Enable SNMP and click Apply.

Entering Administrative Information

For each field, you can enter a maximum of 255 characters.

  1. In the Name field, enter the name of the switch.
  2. In the Location field, enter the physical location of the switch.
  3. In the Contact field, enter the name or organization responsible for the switch.
  4. Click Apply.

Displaying SNMP Statistics

To display SNMP statistics, click Statistics.

Propagated Community Strings

Community strings serve as passwords to authenticate SNMP messages. Each community string is either read-only (RO), which allows MIB-object information to be displayed, or read/write (RW), which allows MIB-object information to be displayed and modified. When a switch joins a cluster, the first read-only and first read/write community string from the command switch are propagated to the new member, and an @esN notation is appended to each propagated string. The N in this notation is a numeric identifier for the switch, and it can be up to two characters long.

On 2900 and 3500 XL switches, the propagated strings are the first read-only and first read-write community string listed on the SNMP Management page. On Catalyst 1900 and 2820 switches, the propagated strings are the last read-only and last read-write community string listed on this page. Because they are necessary for SNMP packet routing, these strings should not be removed.

In addition to propagating strings, the SNMP configuration can also contain user-defined community strings.

Adding and Removing Community Strings

Community strings serve as passwords for SNMP messages. You can enter community strings with read only (RO) or read/write (RW) capabilities. SNMP requests with read-only capability allow you to display of MIB-object information. SNMP requests with read/write capability allow you to display and set MIB object information.

To add a new community string:

  1. In the New Community String field, enter a character string (of any length) into the String field.
    If you are configuring a community string on a cluster member, the string should be unique in the cluster.
  2. Click RO or RW.
  3. Click <<Add<<.

To remove an existing community string:

  1. In the Current Strings list, select the community string to be deleted.
  2. Click Remove.

Adding and Removing Trap Managers

A trap manager is a management station that receives traps, which are the system alerts generated by the switch. By default, no trap manager is defined, and no traps are issued.

To add a new trap manager:

  1. In the New Manager IP Address field, enter the IP address of the new trap manager.
  2. In the New Manager Community field, enter a community string (of any length) for the new trap manager.
  3. Select one or more of the following checkboxes to limit the traps a trap manager receives:
    Send config traps to generate a trap on all changes to the switch configuration.
    Send SNMP traps to generate the supported SNMP traps.
    Send TTY traps to generate a trap when the switch starts an ASCII (management console) session.
    Send C2900/C3500 traps to generate 2900 or 3500 XL specific traps, such as the trap on address violation or broadcast storm level exceeded. These traps are included in the private enterprise MIB.
    Send vtp traps to generate a trap for each VLAN Trunk Protocol (VTP) change (Enterprise Edition Software only).
    Send vlan membership traps to generate a trap for each VLAN Membership Policy Server (VMPS) change (Enterprise Edition Software only).
  4. Click <<Add<<.

To remove an existing trap manager:

  1. In the Current Managers list, select the trap manager to be deleted.
  2. Click Remove.