User's Manual

Key Considerations 751
values. See “Determining Appropriate Retry and Timeout Periods” on
page 701
for details of how to do determine appropriate values.
If you have already determined what appear to be appropriate values for
the remote site then the problem may be caused by the amount of traffic
generated by the discovery process itself. If that is the case then you may
either try increasing the values further still to allow for the overhead of
the discovery process, or try focusing the discovery on those devices that
are most important for you to monitor and manage. Details of the latter
approach are given in “
Configuring Discovery” on page 710.
If you try increasing the numbers of retries and timeout periods to allow
of the overhead of the discovery process then be aware that this will
increase the time it takes 3Com Network Director to determine that a
device at that site has stopped responding when it is monitoring or
managing that device.
See “
Determining Appropriate Retry and Timeout Periods” on page 701
for more information on the issues that this causes.
Problems with
Discovering WAN
Routers
Depending upon your network configuration you may find that
discovering a subnet that a WAN router has an IP address on fails to
discover the WAN router, does not determine the features and
configuration of the WAN router, or only shows the WAN router as a
MAC-only device in the map. There are various reasons why this may
occur:
■ If the WAN router is owned and managed by your service provider
then 3Com Network Director will be unlikely to be able to discover
them at all. While the onus for the management of the WAN router is
on your service provider in such a network configuration, note that
this will prevent you from being able to monitor the utilization of your
WAN links from within 3Com Network Director.
■ The WAN router may have had its SNMP community strings changed
from the factory defaults. 3Com recommends that you change the
SNMP community strings from their factory defaults on all
SNMP-capable devices in your network, as this will increase the
security of your network infrastructure. If you have changed the SNMP
community strings of your WAN router then you should enter the new
values in the Community Strings step of the Network Discovery
wizard. See “
Community Strings Pane” on page 118 for more details.