User's Manual

144 CHAPTER 4: DISCOVERING THE NETWORK
Also, you should try to ensure that the IP addresses of the devices on your
subnet are all within a small set of ranges, with few or no gaps between
the devices on each range and then explicitly specify those ranges in the
Network Discovery wizard. If 3Com Network Director has to ping lots of
addresses that don’t exist, the discovery time can greatly increase as it is
waiting for lots of timeouts.
See “
Using 3Com Network Director On A Multi-Site Network” on
page 681
for more information on configuring the timeouts and retries
appropriately within your network.
Discovery Report
Errors and
Warnings
The Discovery report contains a list of problems that were encountered
during the discovery process. For the detecting devices part of discovery,
these are grouped by subnet. For the topology part of the discovery
process, the problems are grouped by multinet.
Discovery Section
The potential issues that may be detected and reported in the detecting
devices phase of discovery are listed below, along with their potential
causes:
This subnet can contain more devices than 3Com Network Director
currently allows during discovery, and will therefore not be
discovered
Subnets that can contain more than 65535 devices can take an extremely
long time to discover. Therefore, 3Com Network Director ignores these
subnets during all discovery operations. This message can only occur if
you chose the second option on the first pane of the Network Discovery
wizard, since this is where 3Com Network Director interrogates any
routers it detects in order to determine the additional subnets to discover.
If you still wish to discover this subnet then you should use the Specify
Subnets option in the wizard and use restricted IP ranges.
3Com Network Director failed to resolve the MAC addresses for
the following devices
3Com Network Director needs to determine the MAC addresses of
devices for use in the topology process. For non-SNMP devices 3Com
Network Director achieves this by reading the ARP cache of a router or, if
the devices are on the local subnet, it reads the ARP cache of the PC
running 3Com Network Director. This message may be logged if 3Com