Key Concepts 683

being much slower to respond than local devices. This is normal behavior in a multi-site network. However, this delay may result in 3Com Network Director incorrectly reporting these devices as having slow response times.

If the additional latency caused by WAN links is too high or if the WAN links are unreliable then 3Com Network Director may conclude that some remote devices are not responding at all. This will affect not only the monitoring of these devices but will also prevent 3Com Network Director from performing operations such as Network Discovery, Backup, Restore, and Agent Update on these devices.

Active monitoring of a remote site causes 3Com Network Director to generate additional management traffic to the devices at that site. This increases the utilization of the WAN links between the local and remote site. This increased utilization may increase the latency of the WAN links and, if the increase causes the WAN links to become oversubscribed, may result in the routers at either end of these links discarding packets that are destined for the links.

See “Monitoring Techniques” on page 276 for more details of active monitoring.

3Com Network Director provides the following features to address these issues:

Configurable timeouts

Configurable retries

Configurable poll rates for active monitoring

Configurable monitoring modes

Configurable discovery options

Configurable monitor thresholds

More details of each of these features are provided below.

In addition, if you manage your WAN routers directly, 3Com Network Director will discover the WAN links in your network and add them to the map, allowing you to monitor the usage of your WAN.

Configurable Timeouts

3Com Network Director communicates with devices by sending requests and waiting for responses. If a request or response packet is dropped

Page 687
Image 687
HP Network Direr Software Products manual Configurable Timeouts