Appendix C - SNMP Checklist

LANsurveyor queries network equipment that supports SNMP (or "managed devices") to gather important connectivity information for network maps. SNMP data allows LANsurveyor to identify routers, switches, and connectivity between networking hardware and other systems.

If LANsurveyor has access to a device's SNMP MIB-II agent, the device will be listed under SNMP Nodes in the left-hand map navigation. LANsurveyor requires read-only access to SNMP for map drawing; read-write access is not required.

LANsurveyor identifies switches using the SNMP Bridge MIB (RFC 1493) and hubs using the SNMP Repeater MIB (RFC 2108). If LANsurveyor has access to these MIBs, LANsurveyor can map port connectivity. If your routers and switches are not displayed in the left-hand navigation, use this checklist to troubleshoot your SNMP access.

1. Does your device support SNMP?

SNMP-capable devices are sometimes called "smart" or "managed." You may need to check with the device's manufacturer to make sure.

2. Is SNMP enabled?

Some devices require you to specifically enable SNMP.

3. Are you using the correct SNMP community string?

Community strings, like passwords, are case sensitive. Make sure the correct community string is entered into the Create a New Network Map dialog.

4. Is the computer running LANsurveyor on the access control list for your device?

Many devices limit SNMP access to a specific IP address or address range. This is configured using the switch management interface, generally via a web browser.

5. Is the device too busy to respond to SNMP queries?

If a device is at or near 100% utilization, it may not have the resources available to respond to SNMP queries.

6. Is there something between you and the target device that's preventing access?

Some sites have firewalls around their routers that prevent access. LANsurveyor uses UDP port 161 for SNMP queries.

7. Is the timeout sufficiently long?

Increase the SNMP Query Timeout in LANsurveyor Options dialog box if queries are sent across particularly slow or busy links.