HP Network Direr Software Products manual Configuration

Configuration 707

response monitoring for all other devices. The importance of a device is based upon its features and links, but not upon its physical location within the network. It also automatically selects the poll rates for the monitored devices, based upon the number of devices in the map and not upon their location.

As a result, using automatic monitoring mode in a multi-site network may result in many or all of your remote devices being monitored in full monitoring mode. This can cause a large amount of monitoring traffic to be generated over the WAN links, which may result in increased latency to the remote sites, or even oversubscription of the WAN links. This can be further exacerbated if the selected poll rate causes the remote devices to be polled frequently.

3Com recommends that, when monitoring a multi-site network, you do not use automatic monitoring mode. Instead it is recommended that you manually tune the monitoring of your network based upon locality and importance of the devices.

Before you can do this you will need to determine suitable monitoring modes and poll rates for the devices in your network. The exact settings for your network will depend upon your individual monitoring requirements. However, the following pointers may be used to guide your decision:

Where possible, use either the response monitoring for remote devices. While response monitoring still polls remote devices, it generates very little traffic with each poll and so can greatly decrease the amount of traffic generated on your WAN links when compared with full monitoring mode.

SNMP traps only monitoring mode generates even less traffic than response monitoring mode, as traffic is only generated when there is a problem with the device. However, SNMP traps only monitoring mode does not allow 3Com Network Director to determine when the device has stopped responding, and so can delay remedial action.

Note that active monitoring (i.e. the full monitoring and response monitoring modes) poll on a regular basis. If a particular remote site is accessed via a dial-on-demand link then active monitoring may force this link to be permanently active or, at the very least, will cause the link to be re-established on a regular basis.