Defining Eigen Variables

Eigen Value is used to group devices into Eigen Group, forming a Member NI. Eigen Value is generated by eigen variables which can be defined by Visual Parser, system data, CSV input data, L3/L2/IPv6 topology data, Subnet and VLAN group.

1. Click Group by Eigen Values, then click on + Add Variable.
   
2. In the All Variables window, click Add Variable. You can add variables from:

• Existing parsers in Parser Library
• System data:
  • Device property
  • Interface property
  • Topology data
  • VLAN group
  • Subnet
    

• New parser
• CSV input variables.
• ADT
  

3. You can create compound variables from the currently selected variables.
   Example: To check the MTU mismatch between devices, you can create a compound variable this_device_info with the formula $thisDevice + $localInteface. This compound variable will uniquely identify a local interface across the network if the device hostname is unique.
   
   1. Click Group by Eigen Values, then click  + Add Variables.
   2. In the All Variables Window, click  + Add Variables and select Add Variable from System Data.
   3. Select L3 Topology from the drop-down list and select all of the four variables.
      
   4. Click and select Add Compound Variable.
      
   5. Define the string variable This_device_info with the definition $thisDevice + $localInteface.
      
   6. Also, you can create the compound variable $neigbor_device_info with the definition $neighborDevice + $neighborInterface.
      
   7. NetBrain will create two eigen groups for a pair of this_device_info and neigbor_device_info as (R1e0, R2e0) and (R2e0, R1e0).
      If the order is not important and only one Eigen Group needs to be created, you can ignore variable orders by checking the Ignore Variable Order option.
      

Eigen Group

Eigen Group is used to divide devices with the same Eigen Value into a group in three steps:

1. NetBrain computes each device’s Eigen Value based on selected variables. For single device diagnosis, one variable such as the hostname can be the Eigen Value; For the neighbor level logic, multiple variables such as two neighbor device hostnames or neighbor interface names can be the Eigen Value.
2. The devices with the same Eigen Values will form an Eigen Group.  
3. The devices in each group will form a unique member NI.

Merge group via variables

By default, NetBrain will group the devices with the same Eigen Value. In some cases, you may want to group devices even if some Eigen Values are different.

Example: To check the neighbor relationship between P and PE devices, the P device and its PE devices need to be added to the same Eigen Group.

1. Add four Eigen Variables: $name, $BGP_as_number, $nbr_device, $local_IP.
2. Ignore the order of $name and $nbr_device by checking Ignore Variable Order option.
   
   
3. Click Populate Data to generate four Eigen Groups for each pair of P and PE neighbors.
   
   
4.  Enable the merge variables option and select the variable as , so that the devices with the same as number will be merged into one group.
   
   
5. Click Populate Data again, the four Eigen Groups will become one group.