Interface MTU Mismatch Check – Check All Interfaces

Define a Network Intent Template (NIT) to check the interface MTU mismatch. This requires defining a macro variable on the spoke device. This topic primarily focuses on defining the neighbor pair replication and provides a brief overview of the seed intent creation process. For detailed steps on creating an intent, refer to Create Network Intent. The procedure is as follows:

Step1: Define a Seed Intent

1. Add the device “BJ_core_3550” and run the commands show interface and show cdp neighbor detail on it as follows:
   1. show interface:
      1. Run the command and retrieve the MTU information for all interfaces.
      2. Parse the variables as shown in the output table in the image below.

      

   2. show cdp neighbor detail:
      1. Run the command and retrieve the interfaces of the current device as well as the interfaces and details of its neighboring devices.
      2. Parse the variables as shown in the output table in the image below.

      

   3. Merge the above two parsed tables.

      

2. Add the device “BJ*POP” and run the command show interface f0/0 to retrieve the interface details and its MTU value.

   

3. Set a macro variable for this device interface, with the command defined as show interface $intf. Use it to get all neighbor interfaces and MTU values. Then, use this macro variable to create a diagnosis to compare the MTU of this device and device “BJ_core3550”.

   

   Note:  When executing an intent to check the match between a device and its neighbor devices, you can define a diagnosis message that specifies any mismatched neighbor device. Use the variable $this_device.Hostname for other device and $this_device for the host device in the diagnosis message. This ensures that device names are accurately reflected in the messages during intent execution.

Step 2: Define the Neighbor Pair Replication

Enable and define the neighbor pair replication.

1. Assign roles for the seed devices: Designate “BJ_core_3550” as the hub device and “BJ*POP” as the spoke device of “BJ_core_3550”.
2. Define the neighbor variable logic for the hub device. In this case, use the cdp_nbr column from the table parsed by the show cdp neighbor detail command to identify neighbors.



3. Define the macro variable for the spoke device by assigning values directly from the nbr_intf column in the merged table.



4. Run this seed intent to view the result.