Task 1.1 vtp pruning

Hi All,

Above task 'Manually configure your network to behave as though vtp pruning has been enabled'. I came across a task like this in an earlier lab and was slightly confused by the answer and relvevant blog posts. Can anyone shed any light on the correct methodology they use to solve this or a similar type task ? I know it works fine by what is in the solutions , I just want to know what is the best way to solve it.

Thanks in Advance !


  • Just looking at your question the first thing that pops to mind is manaully removing vlans off of trunks via the switchport trunk allowed vlan [list] command(s).  You really have to have a grasp on your traffic flow in the network though, as you can easily prune needed vlans off of a trunk.  I may be way off, I will have to look at this lab now.

  • pls can some one give tips on how to approach this question

    can we enable pruning first and identify the vlans that are pruned and then remove them from the switport trunk

  • Here's how I went about it:

    Pruning works by blocking a vlan on a trunk unless the neighbor requests it, so you got to ask yourself what vlans the switch at the other end would ask of me.

    1. disallow all vlans on all trunks

    2. draw a l2 two diagram and identify which vlans are local to each switch, you'll come up with the following list:

    SW1:      16       38     45      47

    SW2:      16               45      47      63

    SW3:                         45                63          3003

    SW4:                         45

    (alternatively you could just check which spantrees still have an instance after blocking all trunks, but in this scenario you'll miss the vlans that were missing in the initial configs).

    3. From here you can quickly (the task still took me an hour) grasp which switch needs to talk with which over what vlans, implement as needed.

    Vlan 45 should be omitted if you read the next task, plus in that one you'll have to enable 100 and 200 between SW1 and SW2.

    4. Check your topology diagram and make sure every ethernet node can ping its direct neighbors (except vlan 45) and correct any mistakes if you can't ping.



  • Lukas,


    I really like your method on this one.  Nice and simple.


    You could also add the same VLANs as the allowed list.  If it's not there it will add it, if it is, it will skip it.


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