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Host Discovery

 

This task can be used to create valid profile entries within a range of IP addresses, crawl the network based on ARP information from a set of seed routers, or validate an existing router profile.

In addition to creating a router profile, a results file will be created to indicate which IP addresses are unreachable and which are reachable but undiscoverable. If a device is unreachable, the user should determine why it could not be pinged. If it is undiscoverable, the user should check the SNMP get community string. For example, the SNMP string could be wrong, the incorrect device may have been specified, the wrong SNMP version may have been used, or perhaps the timeout was not set long enough.

Before performing a host discovery, a router profile can be created to specify IP addresses that the host discovery will attempt to reach. In addition to specifying individual IP addresses, ranges of IP addresses can also be specified within brackets in which to search for new devices. For example, “10.1.[1-3].[1-3]” would include 10.1.1.1 to 10.1.1.3, 10.1.2.1 to 10.1.2.3, and 10.1.3.1 to 10.1.3.3. Note that using the regular expression can greatly increase the number of routers to test for a connection beyond the number of router profile entries, and therefore should be used with care.

After creating the router profile for IP addresses to discover from, the user should run the Host Discovery task and specify the IP addresses and IP addresses ranges from the router profile to discover devices in. In the Discovery Options tab, the user should specify the file path in which to save the Generated router profile and Generated result output file. This generated router profile can later be re-imported in the router profile. When doing so, the re-import will try to re-encrypt the already encrypted passwords. Therefore after importing the router profile, the passwords should be modified through the graphical interface, for example, through a global modify of the router profile entries.

The Host Discovery task also provides an optional reconciliation feature. Reconciliation is used only when you have a relatively static or unchanging network. First, the user should have created a golden profile, which is specified as the comparison profile in the Discovery Options tab. If new devices are found or if any are missing, then the output results will indicate the differences relative to the golden profile.

Figure 1: Host Discovery Profile Window
Host Discovery Profile Window

Table 1: Host Discovery Profile Parameters

Task Parameter

Description

Report errors to Event Server

If checked, any errors regarding this task will appear in the Event Browser.

Router Profiles

This drop-down menu selects a profile from the Router Profiles window, accessed via the Task Manager. Once a router profile is selected, the table on the left will be populated with all routers from the profile. Select which routers to include in the data collection by selecting routers from the left table and clicking the Add button to move them to the right table.

  • For information on how to create router profiles, see Creating a New Router Profile.

Table 2: Host Discovery Profile Collection Options

Collection Options

Description

Check this if you want to save the collected data other than default directory

This option lets you specify the directory to collect the snmp data. The default directory is /u/wandl/data/collection/.LiveNetwork/hostdiscover/

Incremental Data Collection

This option will incrementally collect data from the network. Check this option if you do not want to lose or overwrite data from previous collections. Uncheck this option if you want to collect a fresh network and overwrite data from previous collections.

Table 3: Host Discovery Profile Actions

Action after Collection

Description

Do nothing (Collection only)

This option collects the snmp data and generates the profile from host discovery task but does udpate the Live Network nor modify the specification file and associated files.

Import to Live Network

This option updates the Live Network with the collection results.

Create new Spec

This option will create a new network project based on the information found during host discovery, consisting of the specification file and associated files such as muxloc, intfmap, nodeparam, etc.

Figure 2: Host Discovery Options Tab
Host Discovery Options Tab

Table 4: Host Discovery Options Parameters

Task Parameter

Description

Use “Ping” utility to test whether it is reachable

This tells the IP/MPLSView server to ping each host it is trying to discover. If the host does not respond to ping, it is marked as “unreachable” and will be reported in the result output file (see below), but will not be included in the result profile (see below).

Crawl the network from the selected devices

Discovers additional hosts from the seed profile based on ARP data, using 3 levels of recursion by default.

Generated result profile

The discovered hosts will be saved to this router profile. Click on the “Browse” button to navigate to the desired directory. Note in Figure 30 that the profile is saved to the directory /tmp

Generated result output file

The results of the host discovery task will be written to this file. These results include information on hosts that are unreachable and other collection information not normally saved with a router profile. See Figure 32 for an example output file.

Comparison profile

This allows you to compare the Generated result profile with another IP/MPLSView router profile specified here (for example, a profile that was generated by a past host discovery process). The Generated result output file will indicate information such as “Newly discovered hosts” in the “Reconciliation notes” section of the file. See Figure 32 for an example output file. “Untested devices” indicates hosts in the Comparison profile that are not listed in the newly Generated result profile resulting from this execution of the host discovery task.

File containing IP addresses to skip

The task will skip these IP addresses during the discovery process. The format of this file is simply one IP address per line.

File with optional SNMP get community string(s)

In this file, list one SNMP get community string per line. When the host discovery is being performed, the SNMP get community string specified in the profile will be tried first. If that fails, then each of the SNMP get community strings specified in this file will be tried on the device until one succeeds.

Figure 3: Host Discovery Email Notification Options Tab
Host Discovery Email Notification Options Tab

Table 5: Host Discovery Email Notification Parameters

Task Parameter

Description

Send notification emails

Select this option if you want notification emails to be sent out after each run of the task.

Mail Server

This is the mail server to be used for sending out the notification emails. This is usually a smtp server.

Mail Sender

This will populate the From field in the notification emails.

Mail Recipients

These are the recipients of the notification emails. Separate multiple email addresses with a space.

Mail Subject

This will populate the Subject field in the notification emails.

Figure 4: Sample Results File
Sample Results File

Table 6: Sample Results File Fields

Report Section

Report Explanation

Unreachable IPs

Devices not reachable via ping.

Reachable, but undiscoverable IPs

The device responded to the ping but the hostname was not retrievable via SNMP.

Reconciliation Notes

This section appears if a Comparison Profile is specified in the Discovery Options tab of the Host Discovery window.

Hostname not resolved for the following indicates those devices for which the IP and credentials were available from the comparison profile, but the hostname was not retrievable via SNMP.

Unreachable IPs indicate devices listed in the comparison profile (but which are not in the profile being currently used) that are not reachable. Newly discovered hosts indicates newly discovered devices that are not in your comparison profile.

Untested devices indicates any IP addresses in your comparison profile that are not included in your current Host Discovery task