User's Manual

708 CHAPTER 17: USING 3COM NETWORK DIRECTOR ON A MULTI-SITE NETWORK
In order to avoid this you should use SNMP traps only monitoring of such
a remote site. Alternatively, do not monitor the remote site unless there
are issues that you wish to investigate and then stop monitoring the site
immediately after you have completed your investigations.
Full monitoring mode of remote devices should be reserved for devices
that are critical to the connectivity of the remote site, to the network as a
whole or to the business. These may include WAN and LAN routers, core
switches and critical servers.
If you wish to monitor a link between remote devices then you will need
to ensure that at least one of the devices at the end of the link is
monitored in full monitoring mode; response monitoring mode does not
provide the information required to monitor a link.
You can reduce the impact upon the WAN links of using full monitoring
mode on a remote device by disabling individual monitors on that device
that you are not interested in.
For example, in order to monitor a link between two remote devices at
least one of the devices must be monitored in full monitoring mode. If
you only wished to monitor the devices in response monitoring mode
then you can still approximate this behavior by selecting one of the
devices to use for monitoring the link, monitor this using full monitoring
mode, and then disable any monitors on the device other than the IP Ping
Service monitor and the monitors that are relevant to the link you wish to
monitor.
When you turn off automatic monitoring mode it is important to
remember that this applies to the whole map, not just to remote sites.
You will need to configure appropriate monitoring mode and poll rate
settings for local devices as well as remote devices.
When determining appropriate monitoring modes and poll rates for local
devices it is not normally necessary to consider the impact of the
monitoring traffic upon the network; you should choose monitoring
modes and poll rates for local devices based purely upon the accuracy
and detail that you require for the device.
The appropriate poll rates will depend upon balancing the level of
accuracy you require in your monitoring information against the location
of the device and the available bandwidth in the path to that device.