With the SNMP Management window, you can:
Note: In cluster configurations, some community strings are propagated by the command switch when a member switch joins the cluster. For details, see Propagated Community Strings.
SNMP is enabled by default. It cannot be disabled on Catalyst 1900 and 2820 switches.
To disable SNMP on a 2900 or 3500 XL switch:
In cluster configurations, the command switch receives SNMP requests from the SNMP management station. The command switch responds to the request sent directly to it, and it redirects requests sent to a 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).
SNMP is enabled by default. It cannot be disabled on Catalyst 1900 and 2820 switches. When SNMP is disabled on the command switch, SNMP applications are prevented from accessing the cluster, which makes bandwidth graphs unavailable.
Note: For Cluster Manager features to work properly, SNMP must be enabled with the community string set to "public."
To disable SNMP on a 2900 or 3500 XL switch:
System options are the administrative information that you can assign to a switch that helps identify it. Although SNMP allows a maximum of 255 characters for each System Options field, Cluster Manager software truncates this information to shorter lengths. For this reason, shorter entries are recommended (see individual steps in the following procedure for guidelines).
To assign system options:
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 that is unique for each switch, and it can be up to two digits 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 window. On Catalyst 1900 and 2820 switches, the propagated strings are the last read-only and last read-write community string listed on this window. Because they are necessary for SNMP packet routing, these strings should not be removed on any switch.
In addition to the propagated strings, the SNMP configuration can also contain user-defined community strings.
The command switch uses community strings to route SNMP packets to member switches. Catalyst 2900 and 3500 XL switches support an unlimited number of community strings of any length. Catalyst 1900 and 2820 switches support a maximum of four read-only and four read/write community strings that are up to 32 characters long. When you assign community strings to these switches, limit their length to 27 characters to accommodate the @esN identifier that will be appended (strings longer than 27 characters are truncated to 27 characters).
To add a new community string to a switch:
When you remove a switch from a cluster, all @esN strings on the switch are removed. If the switch rejoins the cluster, the first read-only and first read/write string from the command switch are propagated to the member switch, and the @esN identifier is appended to each string.
Note: Do not remove the first read-only or the first read/write community string from a 2900 or 3500 XL switch; do not remove the last read-only or the last read/write community string from a Catalyst 1900 or 2820 switch. These strings are required for SNMP functions.
To remove an existing community string from the cluster:
If you remove a community string and enter a new one, click the Reload button on your browser to put the change into effect (click Refresh on Internet Explorer).
Note: If you do not reload or refresh the browser, using the Device Reports option produces an error.
A trap manager is a management station that receives traps, which are the system alerts generated by a switch. If a cluster member switch has no IP address, the command switch receives the SNMP traps and relays them to the trap manager. By default, no trap manager is defined, and no traps are issued.
Catalyst 2900 and 3500 XL switches support an unlimited number of trap managers, and community strings for the trap managers can be any length. On these switches, you can enable specific trap types for specific trap managers. Catalyst 1900 and 2820 switches support up to four trap managers, and community string length is limited to 32 characters. You cannot configure specific trap types for specific trap managers on these switches
To add a new trap manager:
To remove an existing trap manager: