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    Scheduling a VLAN Discovery Task

    Once the router profile has been created and validated with the IP addresses and associated SNMP community strings, the next step is to schedule the VLAN Discovery task to collect SNMP data.

    In the Task Manager, select New Task... and select the VLAN Discovery Task. Enter in a descriptive Task Name and then click Next.

    Figure 1: VLAN Discovery Task Parameters

    VLAN Discovery Task Parameters

    Collection Options

    In the top portion of this window select the router profile in the drop down list containing the devices to be collected. Then selected the desired IP addresses or IP address ranges to collect in this router profile, and click Add to move them to the right hand side list.

    The VLAN Discovery results can be imported directly into the Live Network for viewing purposes. Otherwise, select the checkbox “Check this if you want to save the collected data other than default directory” and click Browse to specify the Collection Directory.

    The Incremental Data Collection checkbox is checked by default to retain the data from the previously collected switches when starting a collection. In order to do a fresh collection from scratch, uncheck this option. In that case the old files in the bridge collection directory will be removed before recollecting to that same directory.

    The option “Collect all devices including switches and non-switches” can be used to collect unrecognized device types for discovery purposes.

    For certain hardware, the “Collect dot1dTpFdbTable” can also be collected to stitch links based on the forwarding table. However, this is often not a reliable source for link stitching.

    Include devices whose IP addresses end with .0 or .255: By default these IP addresses will be ignored when collecting from a range of IP addresses.

    Mark filename as Duplicate for collected files with duplicate hostnames: Since the same device may have multiple IP addresses, there may be more than one collected file for the same hostname. Select this option to keep track of the duplicate hostname.

    Discovery Options

    There are two methods that can be used for discovering additional devices-- pingsweep or autodiscovery. Autodiscovery is used to automatically discover other devices that are known to the task’s “seed” devices via neighbor discovery / crawling, specifically through SNMP-based ARP or Cisco CDP table information. Pingsweep is used to scan any specified IP address ranges before SNMP collection to determine which IP addresses are reachable. Note that both of these methods are advanced features which require a separate license from the VLAN discovery.

    1. To enable auto discovery, select the Discovery Options tab, and select “Enable auto discovery (Crawl the network)”.

      Figure 2: VLAN Discovery Options

      VLAN Discovery Options
    2. The method of autodiscovery can be selected to include both ARP Table and Cisco CDP Cache Table or only one of these methods. In case polling the ARP cache will put a burden on the network, it may be desirable to uncheck this option, and to use the alternative Cisco CDP Cache Table instead (Cisco devices only). Alternatively, the pingsweep option on the Advanced tab may be preferred.
    3. The “Maximum hop count (default=3)” is used to specify how many recursive levels to discover based on arp/mac address table. Valid values are between 2 and 5. Note that the hop count mentioned here is a not the same as the physical hop count, but refers to the number of recursive levels. For example, if A’s ARP table contains B, and B’s ARP table contains C, then C could be discovered from the seed device A via a hop count of 2.
    4. Enter in the “Maximum number of discovery threads (default=5) “ to divide the task into multiple threads instead of running everything sequentially. To speed up the collection, a higher number can be used, for example, 10. However, a smaller number can be used to minimize the load on the network.

    Advanced Options

    On the Advanced tab are options to perform a ping sweep to collect data, specify an alternative community string list, specify a directory in which to log the progress, warnings, and errors encountered during the polling, and specify a location in which to save the resulting router profile for the valid IP addresses that are polled.

    Figure 3: VLAN Discovery, Advanced Tab

    VLAN Discovery, Advanced Tab

    Task Parameter


    Generated device profile

    Specify the location of the profile that will be created from the polled devices. The default directory is /u/wandl/data/.TaskManager/profile Using the resulting router profile, devices that are polled via SNMP for VLAN Discovery can then be polled via CLI for additional details such as configuration, interface, and equipment inventory.

    Allow duplicated hostnames in profile

    IP addresses polled during the autodiscovery or pingsweep process may represent the same device, usually indicated through an identical hostname. The default option is to disallow duplicated hostnames, only selecting one IP address per hostname, to prevent polling the same device more than once.

    In some situations, however, the IP address selected by IP/MPLSView may not be accessible to telnet/SSH, although another IP address that was discovered is. This option can determine what the other IP addresses are. A Test Connectivity check can be used to determine the correct profile to choose for a hostname.

    Black/White List File containing IP addresses or ranges to discover (white list) or to skip (black list)

    This is a file containing a list of IP addresses, one per line, that should be ignored by the discovery task. Any bad IP addresses that the task encounters during the discovery will be appended to this file. This is a required file, even if initially empty.

    This file will also allow the specification of a range of IP addresses to permit or deny/block on a line. For example:

    permit 10.0.1.[10-255]
    block 20.0.0.[1-255]

    Either browse for this file or select the Edit icon to create this file. Click the Save button to specify where to save this file, and click the Close button to return to the VLAN Discovery window.

    Alternate Community String File with optional SNMP get community string(s)

    This is a file containing one SNMP community string per line. The VLANDiscovery process will try alternate SNMP community strings from this set if the default/configured SNMP community strings specified in the router profile does not work.

    Either browse for this file or select the Edit icon to create this file. Click the Save button to specify where to save this file, and click the Close button to return to the VLAN Discovery window.

    Domain Names

    To specify the Domain Names, click on the editor button. If the domain is found in the device’s hostname, it will be removed from the hostname for proper link stitching of the devices.

    Log Directory

    This points to the path of the directory that will contain logging information, including the overall progress of the task, the list of devices with reachability status and basic SNMP information, autodiscovery progress via CDP or ARP, and blacklisted IP addresses.

    Select “Create a timestamp subdirectory” if this task will be run more than one time and you would like a separate log directory for each time. A subdirectory will then be created in the log directory according to the timestamp.

    Maximum number of discovery and collection threads (default=5)

    Set the maximum number of simultaneous connections to devices for SNMP polling of bridge files. For example, if set to 5, then the program can connect to 5 devices simultaneously to collect SNMP information.

    Do ping sweep before collecting data

    If this option is selected, devices in the specified IP address range(s) that are reachable via ping sweep will then be polled via SNMP for VLAN details. Select either regular ping or fping (recommended). Note that to use fping, you should specify the file path of the fping program (/u/wandl/thirdparty/fping/fping). For fping, you can specify the number of threads to use and the number of IP addresses per fping, so that different threads can run in parallel. It is recommended to use the default settings

    Collect dot1dTpFdbTable

    This option should not be used in general, since the forwarding table can be large, and it is unreliable to create links based on forwarding table relationships. Devices in the forwarding table may be multiple hops away.

    Remove JUNOS RE extension in hostname

    For JUNOS dual routing engines, the RE extension can be removed from the device’s hostname if this option is selected.

    1. Click Next. The scheduling parameters, as shown in the Schedule Task step of the New Task Wizard shown below, are the same for all task types.
    2. If you have the remote polling module, the Polling Server (Remote Collection Server) selection will be available to select which remote collection server to use, based on User Admin privileges. If your remote collection server does not show up, make sure that it is configured in the /u/wandl/bin/ script, and that the server had been stopped and restarted subsequent to this change.

      Figure 4: VLAN Discovery Scheduling

      VLAN Discovery Scheduling
    3. If you wish to chain a task to run immediately after the VLAN Discovery task, such as the Network Config Data Collection task, then avoid using the scheduled time “Immediately”. Choose instead “Once” and enter a date in the future in “Set Start Time” or select a regularly recurring interval.
    4. Click Finish to continue.

    Check the Task Manager for information on the polling status. When the polling is finished, the topology will be updated on the Standard map.

    Modified: 2016-11-08