You can reduce the time taken to discover devices on a network by increasing the number of processing threads, or reducing the timeout period. This article explains how. This article assumes you have a good understanding of how ManageSoft discovers networked devices as a prelude to bringing them under management, as described in the Discovery and adoption chapter of the ManageSoft Reference: Configuration.
For network exploration based discovery processes, two things govern the length of time a discovery task will take:
- The number of processing threads the discovery task runs.
By default, discovery processes use 10 processing threads. If you allow more threads to execute simultaneously, your network discovery will complete more quickly.
You can increase the number of discovery threads on the Discovery tab of the Discovery and Adoption Properties dialog. See the Discovery and adoption chapter of the ManageSoft Reference: Configuration for instructions.
- The length of time to wait for a response from devices before timing out.
The default values that specify how long to wait for a response from devices are established to provide a balance between the quality of results obtained and the time taken to obtain them. If discovery speed is important, and you are willing to sacrifice some accuracy (for example, by not discovering devices that are slow to respond), you can reduce the length of time to wait for responses.
Reducing the time out period
You can speed up network exploration based discovery by setting default values in the registry that will be used for all subsequent discovery tasks. If sometimes you will perform discovery using only ping sweep, and sometimes with both ping sweep and port scanning, you can set defaults for both types of discovery here. When you schedule the discovery task using the Discovery wizard, the appropriate default values will be used.
- On the administration server, start regedit (Start > run > regedit).
- Expand the HKEY_LOCAL_MACHINE hive until HKEY_LOCAL_MACHINE\SOFTWARE\ManageSoft Corp\ManageSoft\Discovery\CurrentVersion is visible.
- For discovery tasks that perform only a ping sweep during discovery (not port scanning as well), create a new registry string DefaultPingSweepOptions with value -PI -sP. (This is equivalent to setting the Perform network scan using only ping sweep check box on the Discovery Options page of the Discovery wizard. The reason you set it here is so that you can make changes to the options passed to the network discovery tool.)
- For discovery tasks that perform both a ping sweep and port scanning, create a new string DefaultScanOptions with value -PI -sU -sS. (This is equivalent to setting the Perform network scan with ping sweep and individual port scan check box on the Discovery Options page of the Discovery wizard. The reason you set it here is so that you can make changes to the options passed to the network discovery tool.)
- Modify DefaultScanOptions to append the following:
- --host_timeout n, where n is the number of milliseconds to spend scanning a single host before giving up on that IP address. By default, there is no timeout period specified. To speed up your discovery results, a value in the range 1000 to 2000 milliseconds is recommended.
- Modify DefaultScanOptions or DefaultPingSweepOptions to append the following:
- --max_rtt_timeout n, where n is the maximum number of milliseconds to wait for a response after a probe, before retransmitting or timing out. The default value is 9000 milliseconds, but if you want to speed up your discovery tasks, a value in the range 1000 to 2000 milliseconds is recommended.
- Exit regedit.
The values you have specified here will be used next time you use the Discovery wizard to schedule device discovery.
Be aware: ManageSoft uses Nmap to perform network exploration based discovery. You can perform additional configuration of Nmap using the method outlined above. Consult the Nmap documentation at http://www.insecure.org/nmap/data/nmap_manpage.html for details about additional configuration.
Please note that on a 64 bit system the Registry key location is:HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\ManageSoft Corp\ManageSoft\Discovery\CurrentVersion