Copyright: Copyright ® 1996-1997 Cisco Systems, Inc.
Citation: Copyright ® 1996-1997 Cisco Systems, Inc. All Rights Reserved.


Cisco TCP/IP Suite SNMP Agent Help Contents
 Cisco TCP/IP Suite Online Help

SNMP Agent Options

SNMP Agent Procedures

SNMP Agent Concepts


SNMP Agent Commands
Cisco TCP/IP Suite Online Help

SNMP Agent Options

•	System Tab

•	Trap Tab

•	Advanced Tab

•	File Menu

•	Options Menu

•	Help Menu

SNMP Agent Procedures

SNMP Agent Concepts


System Tab

The System tab contains controls that let you identify your workstation to an SNMP server and set the read and write community for your SNMP Agent:

sysDescr

A description of your workstation.  The description can contain up to 255 characters.  Your network administrator might have specific rules for the information to be included in this description (for example, the make and model of the machine, and so forth).  Contact your network administrator for help.

sysContact

The contact information for you or the person responsible for your machine.  The contact information can contain up to 255 characters.  Your network administrator might have specific rules for the information to be included in this field (for example, name, telephone number, email address, and so forth).  Contact your network administrator for help.

sysLocation

A description of the location of your workstation. The description can contain up to 255 characters.  Your network administrator might have specific rules for the information to be included in this description (for example, the building and number of your office, and so forth).  Contact your network administrator for help.

Read Community

A character string that the SNMP Agent uses to authenticate read requests from SNMP servers.  This case-sensitive string can contain up to 255 characters, and defaults to public.  When an SNMP server asks your SNMP Agent to send information to it, the server must include this string or your agent rejects any request the SNMP server makes.  Contact your network administrator for help in setting your read community.

Write Community

A character string that the SNMP Agent uses to authenticate write requests from SNMP servers.  This case-sensitive string can contain up to 255 characters, and there is no default (all write requests are rejected unless a write community is defined).  When an SNMP server tries to make changes to your machines setup (IP routing, ARP, and interface information), the server must include this string or your agent rejects any request the SNMP server makes.  Contact your network administrator for help in setting your write community.

Defaults button

Primes the sysDescr, sysContact, and sysLocation fields with information the SNMP Agent can discover from your workstations setup.  You can change the text to contain the information required by your network administrator.

See Also:

•	Identifying Your Workstation to an SNMP Server

•	Setting Read and Write Communities

•	Setting Up SNMP Authentication Failure Traps


File Menu

The File menu contains these commands:

Start

Starts the SNMP Agent, making it possible for an SNMP network manager to manage your workstation.  The shortcut button is:

Stop

Stops the SNMP Agent, making your workstation unavailable to the SNMP network manager.  The shortcut button is:

Save Settings

Saves the SNMP settings.  You must save the settings for them to be available to the SNMP network manager, and then restart the SNMP Agent.  Restart the SNMP Agent by clicking the Stop button, and then clicking the Start button.  The shortcut button is:

Exit

Exits the SNMP Agent application.  If you exit the application, your workstation cannot be managed by the SNMP network manager.  The shortcut button is:


Start Button

	The Start button, or Start from the File menu, starts the SNMP Agent, making it possible for an SNMP network manager to manage your workstation.


Stop Button

	The Stop button, or Stop from the File menu, stops the SNMP Agent, making your workstation unavailable to the SNMP network manager.


Save Settings Button

	The Save Settings button, or Save Settings from the File menu, saves the SNMP settings.  You must save the settings for them to be available to the SNMP network manager.


Exit Button

	The Exit button, or Exit from the File menu, exits the SNMP Agent application.  If you exit the application, your workstation cannot be managed by the SNMP network manager.


Options Menu

The Options menu contains these commands:

Minimize on Startup

Indicates whether the SNMP Agent should be minimized on the desktop when initially started.  If you automatically start the SNMP Agent during system boot, minimizing the SNMP Agent helps you keep your desktop clear.

Prompt on Exit

Indicates whether you want to be prompted when you try to exit the SNMP Agent application.

Toolbar Help

Enables or disables toolbar help (bubble help), which is the quick popup help you get when passing your cursor over the buttons on the toolbar.

Status Bar

Displays or hides the status bar at the bottom of the SNMP Agent window.

Toolbar

Displays or hides the toolbar, which is the bar of shortcut buttons beneath the menu.


Help Menu

The Help menu contains these commands:

Contents

Displays the contents page of this help file.

Search for Help On

Searches this help files index

How to Use Help

Displays help information for using the Windows help system.

About SNMP Agent

Displays version information for the application.


sysDescr

The sysDescr is a description of your workstation.  The description can contain up to 255 characters.  Your network administrator might have specific rules for the information to be included in this description (for example, the make and model of the machine, and so forth).  Contact your network administrator for help.


sysContact

The sysContact is the contact information for you or the person responsible for your machine.  The contact information can contain up to 255 characters.  Your network administrator might have specific rules for the information to be included in this field (for example, name, telephone number, email address, and so forth).  Contact your network administrator for help.


sysLocation

The sysLocation is a description of the location of your workstation. The description can contain up to 255 characters.  Your network administrator might have specific rules for the information to be included in this description (for example, the building and number of your office, and so forth).  Contact your network administrator for help.


Read Community

The read community is a character string that the SNMP Agent uses to authenticate read requests from SNMP servers.  This case-sensitive string can contain up to 255 characters, and defaults to public.  When an SNMP server asks your SNMP Agent to send information to it, the server must include this string or your agent rejects any request the SNMP server makes.  Contact your network administrator for help in setting your read community.


Write Community

The write community is a character string that the SNMP Agent uses to authenticate write requests from SNMP servers.  This case-sensitive string can contain up to 255 characters, and there is no default (all write requests are rejected unless a write community is defined).  When an SNMP server tries to make changes to your machines setup (IP routing, ARP, and interface information), the server must include this string or your agent rejects any request the SNMP server makes.  Contact your network administrator for help in setting your write community.


Trap Tab

The Trap tab lets you enable SNMP authentication failure traps and set a trap community and trap destinations:

Enable Authentication Failure Traps

Enables the SNMP Agent to send SNMP authentication failure traps to an SNMP trap destination machine.  If an SNMP server contacts your machine with an invalid read or write community string, your SNMP agent sends an authentication failure trap to the SNMP trap destination machine.  The network administrator uses these traps to help maintain the security of your network.  The trap destination only accepts your trap message if your trap community string matches that of the destinations trap community.

Trap Community

A character string that the SNMP Agent sends with traps to SNMP trap destination machines.  The trap destination machines use the trap community string to authenticate your machines message  This case-sensitive string can contain up to 255 characters.  Contact your network administrator for help in setting your trap community.

Trap Destinations

A machine that has been designated to receive SNMP traps.  Contact your network administrator for the list of trap destinations and their trap communities.  The name of a trap destination can be a host name or IP address.

Add button

Adds trap destinations to the Trap Destinations list.

Delete button

Deletes the selected trap destination from the Trap Destinations list.

See Also:

•	Setting Up SNMP Traps


Trap Community

The trap community is a character string that the SNMP Agent sends with traps to SNMP trap destination machines.  The trap destination machines use the trap community string to authenticate your machines message.  This case-sensitive string can contain up to 255 characters.  Contact your network administrator for help in setting your trap community.


Trap Destinations

The trap destination is a machine that has been designated to receive SNMP traps.  Contact your network administrator for the list of trap destinations and their trap communities.  The name of a trap destination can be a host name or IP address.


Add Trap Destination Dialog Box

The Add Trap Destination dialog box lets you add an SNMP trap destination to the list of trap destinations.  Enter the host name or IP address of the trap destination and click OK.


Advanced Tab

The Advanced tab lets you set advanced settings for the SNMP Agent:

Port

The port used for sending and receiving SNMP messages.  The default port is 161.

Maximum Message

The maximum size of SNMP messages, in bytes, that the agent can send or receive.  The size can range from 2048 to 32767.  The default size is 2048.

See Also:

•	Setting Advanced Options


SNMP Port

The SNMP Port is the port used for sending and receiving SNMP messages.  The default port is 161.


SNMP Max Message Size
SNMP Maximum Message Size

The SNMP Maximum Message Size field lets you define the maximum size of SNMP messages, in bytes, that the agent can send or receive.  The size can range from 2048 to 32767.  The default size is 2048.


SNMP Agent Procedures
Cisco TCP/IP Suite Online Help

SNMP Agent Options

SNMP Agent Procedures

•	Starting and Stopping the SNMP Agent

•	Identifying Your Workstation to an SNMP Server

•	Setting Read and Write Communities

•	Setting Up SNMP Traps

•	Setting SNMP Advanced Options

•	Setting SNMP Agent Options

SNMP Agent Concepts


Identifying Your Workstation to an SNMP Server

To identify your workstation to an SNMP server:

1.	Choose the System tab.

2.	Edit the sysDescr, sysContact, and sysLocation fields if they do not contain the desired information.

3.	Click the Save Settings button to save your changes.

Tips:

•	If the Agent is running when you change settings, you must restart the Agent so that the new settings are available to the SNMP network manager. Restart the SNMP Agent by clicking the Stop button,  and then clicking the Start button.

•	You must leave the SNMP Agent application active for it to accept or reject requests from an SNMP server.

•	You can click the Defaults button to reset these fields to their defaults.

•	Your network administrator might have specific guidelines for the information you should provide in the sysDescr, sysContact, and sysLocation fields.  Contact your network administrator for help.

Related Topics

•	Setting Read and Write Communities

•	Setting Up SNMP Traps


Setting Read and Write Communities

To set the read and write communities for the workstation:

1.	Choose the System tab.

2.	Enter the read community string in the Read Community field.

3.	Enter the write community string in the Write Community field.

4.	Click the Save Settings button to save your changes.

Tips:

•	If the Agent is running when you change settings, you must restart the Agent so that the new settings are available to the SNMP network manager. Restart the SNMP Agent by clicking the Stop button,  and then clicking the Start button.

•	You must leave the SNMP Agent application active for it to accept or reject requests from an SNMP server.

•	Contact your network administrator for help in identifying your read and write communities.  These character strings must be known to the SNMP server if the workstation is to be remotely managed.

Related Topics

•	Identifying Your Workstation to an SNMP Server

•	Setting Up SNMP Traps


Setting Up SNMP Traps

Use the Trap tab to set up SNMP traps for your workstation.  The SNMP Agent can issue all standard types of SNMP traps.

•	Enable SNMP Authentication Failure Traps

•	Identify the Trap Community

•	Add Trap Destinations

•	Delete Trap Destinations

•	Disable SNMP Authentication Failure Traps

Related Topics

•	Understanding SNMP Traps

•	Understanding SNMP Communities


Enabling SNMP Authentication Failure Traps

To enable SNMP authentication failure traps:

1.	Choose the Trap tab.

2.	Check Enable Authentication Failure Traps.

3.	Click the Save Settings button to save your changes.

Tips:

•	If the Agent is running when you change settings, you must restart the Agent so that the new settings are available to the SNMP network manager. Restart the SNMP Agent by clicking the Stop button,  and then clicking the Start button.

•	You must leave the SNMP Agent application active for it to accept or reject requests from an SNMP server.

Related Topics:

•	Understanding SNMP Traps

•	Identifying the Trap Community

•	Adding Trap Destinations

•	Deleting Trap Destinations

•	Disabling SNMP Authentication Failure Traps

•	Identifying Your Workstation to an SNMP Server

•	Setting Read and Write Communities


Identifying the Trap Community

To identify the trap community for the trap destination:

1.	Choose the Trap tab.

2.	Enter the trap community string in the trap community field.

3.	Click the Save Settings button to save your changes.

Tips:

•	If the Agent is running when you change settings, you must restart the Agent so that the new settings are available to the SNMP network manager. Restart the SNMP Agent by clicking the Stop button,  and then clicking the Start button.

•	You must leave the SNMP Agent application active for it to accept or reject requests from an SNMP server.

•	Contact your network administrator for the trap community string you should use.

Related Topics:

•	Understanding SNMP Traps

•	Enabling SNMP Authentication Failure Traps

•	Adding Trap Destinations

•	Deleting Trap Destinations

•	Disabling SNMP Authentication Failure Traps

•	Identifying Your Workstation to an SNMP Server

•	Setting Read and Write Communities


Adding Trap Destinations

To add a trap destination:

1.	Choose the Trap tab.

2.	Click the Add button.  The Add dialog box appears.

3.	Enter the host name or IP address of the trap destination and click OK.

4.	Click the Save Settings button to save your changes.

Tips:

•	If the Agent is running when you change settings, you must restart the Agent so that the new settings are available to the SNMP network manager. Restart the SNMP Agent by clicking the Stop button,  and then clicking the Start button.

•	You must leave the SNMP Agent application active for it to accept or reject requests from an SNMP server.

•	Contact your network administrator for the trap destinations you can use.

Related Topics:

•	Understanding SNMP Traps

•	Enabling SNMP Authentication Failure Traps

•	Identifying the Trap Community

•	Deleting Trap Destinations

•	Disabling SNMP Authentication Failure Traps

•	Identifying Your Workstation to an SNMP Server

•	Setting Read and Write Communities


Deleting Trap Destinations

To delete a trap destination:

1.	Choose the Trap tab.

2.	Click the trap destination you want to delete.

3.	Click the Delete button.

4.	Click the Save Settings button to save your changes.

Tips:

•	If the Agent is running when you change settings, you must restart the Agent so that the new settings are available to the SNMP network manager. Restart the SNMP Agent by clicking the Stop button,  and then clicking the Start button.

•	You must leave the SNMP Agent application active for it to accept or reject requests from an SNMP server.

Related Topics:

•	Understanding SNMP Traps

•	Enabling SNMP Authentication Failure Traps

•	Identifying the Trap Community

•	Adding Trap Destinations

•	Disabling SNMP Authentication Failure Traps

•	Identifying Your Workstation to an SNMP Server

•	Setting Read and Write Communities


Disabling SNMP Authentication Failure Traps

To disable SNMP authentication failure traps:

1.	Choose the Trap tab.

2.	Uncheck Enable Authentication Failure Traps.

3.	Click the Save Settings button to save your changes.

Tips:

•	If the Agent is running when you change settings, you must restart the Agent so that the new settings are available to the SNMP network manager. Restart the SNMP Agent by clicking the Stop button,  and then clicking the Start button.

•	You must leave the SNMP Agent application active for it to accept or reject requests from an SNMP server.

•	The SNMP Agent can send the other types of SNMP traps even if you disable authentication failure traps.

Related Topics:

•	Understanding SNMP Traps

•	Enabling SNMP Traps


Setting Advanced Options

To set advanced settings:

1.	Choose the Advanced tab.

2.	Enter the port number that should handle SNMP messages in the Port field.

3.	Set the maximum message size for the SNMP messages in the Maximum Message field.

4.	Click the Save Settings button to save your changes.

Tips:

•	If the Agent is running when you change settings, you must restart the Agent so that the new settings are available to the SNMP network manager. Restart the SNMP Agent by clicking the Stop button,  and then clicking the Start button.

•	You must leave the SNMP Agent application active for it to accept or reject requests from an SNMP server.

•	Contact your network administrator for the appropriate port and maximum message size values.  Usually the default values are adequate.


Setting SNMP Agent Execution Options

To set the execution options for the SNMP agent:

1.	Choose the Options menu.

2.	Check Minimize on Startup if you want the SNMP Agent minimized on the desktop when started.

3.	Check Prompt on Exit if you want to be prompted before exiting the SNMP Agent application.

4.	Check the Toolbar Help, Status Bar, and Toolbar options if you want these features displayed.

Related Topics:

•	Starting the SNMP Agent Automatically


Starting and Stopping the SNMP Agent

The SNMP Agent must be running and started for the SNMP network manager to have access to your workstation.  The best setup is to start the SNMP Agent whenever you boot your system.

•	Starting the SNMP Agent

•	Starting the SNMP Agent Automatically

•	Stopping the SNMP Agent

•	Exiting the SNMP Agent Application


Starting the SNMP Agent

To start the SNMP Agent:

•	Click the Start button, or check Start on the File menu.

Tips:

•	To have your workstation effectively managed by the SNMP network manager, you must start the SNMP Agent every day, preferably during system startup.

•	Whenever you make a change to SNMP Agent settings, click the Stop button and then click the Start button.  This reloads the SNMP information so that the SNMP network manager can see the updated settings.

Related Topics

•	Starting the SNMP Agent Automatically

•	Setting SNMP Agent Options

•	Stopping the SNMP Agent

•	Exiting the SNMP Agent Application


Starting the SNMP Agent Automatically

To start the SNMP Agent automatically:

1.	In the Windows Program Manager, open the Cisco TCP/IP Suite folder.

2.	Select the SNMP Agent icon.

3.	Choose Copy from the File menu.

4.	Select the Startup Folder in the To Group field and click OK.

Tips:

•	To have your workstation effectively managed by the SNMP network manager, you must start the SNMP Agent every day, preferably during system startup.

•	To start the SNMP Agent minimized on your desktop, check Minimize on Startup on the Options menu.

•	Ensure that the Start button is selected (or Start on the File menu is checked).  Otherwise, the SNMP Agent is not available to the SNMP network manager.

•	Whenever you make a change to SNMP Agent settings, click the Stop button and then click the Start button.  This reloads the SNMP information so that the SNMP network manager can see the updated settings.

Related Topics:

•	Starting the SNMP Agent

•	Setting SNMP Agent Options

•	Stopping the SNMP Agent

•	Exiting the SNMP Agent Application


Stopping the SNMP Agent

To stop the SNMP Agent (without exiting the program):

•	Click the Stop button, or check Stop on the File menu.

Tips:

•	If you stop the SNMP Agent, the SNMP network manager cannot access and manage your workstation.

Related Topics

•	Starting the SNMP Agent

•	Setting SNMP Agent Options

•	Exiting the SNMP Agent Application


Exiting the SNMP Agent Application

To exit the SNMP Agent application:

•	Click the Exit button, or choose Exit from the File menu.

Tips:

•	If you exit the SNMP Agent, the SNMP network manager cannot access and manage your workstation.

Related Topics

•	Starting the SNMP Agent

•	Setting SNMP Agent Options

•	Stopping the SNMP Agent


SNMP Agent Concepts
Cisco TCP/IP Suite Online Help

SNMP Agent Options

SNMP Agent Procedures

SNMP Agent Concepts

•	Understanding the Simple Network Management Protocol (SNMP)

•	Understanding SNMP Communities

•	Understanding SNMP Traps

•	For More Information About SNMP


Understanding the Simple Network Management Protocol (SNMP)

The Simple Network Management Protocol (SNMP) allows remote SNMP network managers to manage other machines on a network (for example, routers, hubs, and workstations), if both the SNMP network manager and managed machines abide by the SNMP rules.  SNMP is an open standard, so you can mix and match SNMP network managers and SNMP agents (managed machines) from different vendors.

Because SNMP network managers are capable of changing the configuration of managed machines, SNMP uses passwords called communities to ensure that only SNMP network managers known to the agent machines (for example, your workstation) are allowed to view or change information on the agent machine.  Every SNMP message sent to an SNMP agent must include a valid community name.  Otherwise, the SNMP agent sends notification of the authentication error to an SNMP network manager that is handling these errors (called traps).

SNMP Agents can also send traps for other kinds of events.  The SNMP Agent sends all standard SNMP traps.

SNMP maintains information about your workstation in a management information base (MIB).  The SNMP Agent complies with the MIB-II definition, which is the Internet standard.  If you change the information about your workstation (for example, the description or trap destinations), you must restart the SNMP Agent so that the new information is available to the SNMP network manager.  Restart the SNMP Agent by clicking the Stop button,  and then clicking the Start button.

The SNMP Agent is based on the SNMPv1 definition.

See Also:

•	For more information about SNMP and MIBs


Understanding SNMP Communities

An SNMP community is a type of password used by the SNMP network manager and SNMP agents to ensure that only known and trusted machines can send and receive SNMP messages to each other.  Every SNMP message includes a community name, so that every message can be validated.

These are the types of community names:

Read	The SNMP network manager must use the correct read community name when asking your SNMP agent to send it information about your machine.  The default read community name is public.
Write	The SNMP network manager must use the correct write community name when asking your SNMP agent to change some characteristic about your configuration.  There is no default write community name.
Trap	If certain events happen in your workstation (for example, you reboot your machine, or an SNMP network manager sends an SNMP message that contains the wrong read or write community password), your SNMP Agent sends a trap message to an SNMP network manager.  For your trap message to be handled, the trap community name you send must match the name known to the target SNMP network manager.  There is no default trap community name.
See Also:

•	Setting Read and Write Communities

•	Identifying the Trap Community

•	Understanding SNMP Traps


Understanding SNMP Authentication Failure Traps
Understanding SNMP Traps

One of the main uses of SNMP is to make it easy to keep track of important events that occur on the managed network.  To help automate network management, SNMP agents send trap messages to the SNMP network manager when certain events occur.  For example, your workstation sends traps when you reboot it.  The SNMP Agent sends all standard SNMP traps.

One important type of SNMP trap is the authentication failure trap.  Because SNMP network managers have access to sensitive configuration settings for the machines on a managed network, it is important that the network administrators guard against breaches in network security that involve illegitimate use of SNMP messages.

For this reason, every SNMP message must be authenticated by SNMP network managers and SNMP agents using passwords called communities.  If your agent gets an SNMP message that contains an incorrect community name for the type of operation requested, your agent sends a message to another SNMP network manager.  This message contains information about the request your agent received:  what the message requested, and why your agent would not fulfill the request.

Ask your network administrator for the address of the machines that handle traps before setting up the SNMP Agent to handle traps.


For More Information

Recommended Reading

For an excellent conceptual overview of TCP/IP networking concepts, we recommend the following books:

Comer, Douglas E., Internetworking with TCP/IP, Volumes I and II, Prentice Hall

Black, Uyless D., TCP/IP and Related Protocols, McGraw-Hill

Recommended books for users of all levels.

Relevant RFCs

For more information on the SNMP specifications, consult the following RFCs:

Structure of Management Information	RFCs 1155, 1212, 1215
Management Information Bases	RFC 1213
SNMP	RFC 1157
SNMP Administrative Model	RFC 1351
Learn how to get RFCs.