User's Manual

Components 693
determine which end is nearest to the local site and monitor that. This
will prevent the monitoring from generating traffic over the WAN link.
■ If you have a point-to-multi-point WAN configuration and have
logically grouped the interfaces involved together, or wish to monitor
a point-to-point link at both ends, then you can start monitoring on all
of the links that form a part of that connection.
The monitors available for WAN interfaces in
3Com Network Director are
all based upon the statistics gathered by the MIBII ifTable. If one or more
of the statistics available from this table are not collected by the router for
the WAN interface that you wish to monitor then
3Com Network Director
will only be able to provide partial monitoring information.
Please refer to the user guide for your router for more information on
which statistics are gathered for which WAN interface types.
Configuring WAN Link Monitors
Thresholds can be set for WAN link monitors in the same manner as for
all other monitors. See “
Setting Thresholds for Monitor-Based Events” on
page 356
for details of how to do this.
In addition to setting the thresholds for WAN link monitors you can also
configure the speed used to calculate values for the utilization monitor.
This allows you to configure the speed of a WAN link to represent any
service level agreement or policy you may have in place for that WAN link.
For example, although the WAN interface may have a speed of 2Mbps,
you may have an agreement with the ISP that allows you an average
throughput of 1Mbps, and only allows you to burst traffic to 2Mbps for
short time periods without incurring additional cost. By altering the
speed of the WAN link to 1Mbps the utilization calculation will be based
upon the service level agreement, and not the maximum link speed. In
conjunction with an appropriate threshold setting, this will allow you to
spot when you are about to exceed the limits allowed by the service level
agreement and so take appropriate action.
3Com Network Director allows you to set thresholds in excess of the
theoretical maximum value for the monitor. This is particularly useful for
WAN links that have complex service level agreements or policies applied
to them.