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CCNP BCMSN(642-812) Lab – STP(New)

Posted on May 20, 2009

Acme is small export company that has an existing enterprise network comprised of 5 switches;
CORE,DSW1,DSW2,ASW1 and ASW2. The topology diagram indicates their desired pre-VLAN spanning tree mapping.
Previous configuration attempts have resulted in the following issues:
– CORE should be the root bridge for VLAN 20; however, DSW1 is currently the root bridge for VLAN 20.
– Traffic for VLAN 30 should be forwarding over the gig 1/0/6 trunk port between DSW1 and DSW2. However VLAN 30 is currently using gig 1/0/5.
– Traffic for VLAN 40 should be forwarding over the gig 1/0/5 trunk port between DSW1 and DSW2. However VLAN 40 is currently using gig 1/0/6.

You have been tasked with isolating the cause the these issuer and implementing the appropriate solutions. You task is complicated by the fact that you only have full access to DSW1, with isolating the cause of these issues and implementing the appropriate solutions, Your task is complicated by the fact that you only have full access to DSW1, with the enable secret password cisco. Only limited show command access is provided on CORE, and DSW2 using the enable 2 level with a password of acme. No configuration changes will be possible on these routers. No access is provided to ASW1 or ASW2.

812-LAB

Solutions:

DSW1#conf t

DSW1(config)#spanning-tree vlan 20 priority 61440

DSW1(config)#int g1/0/5

DSW1(config-if)#spanning-tree vlan 40 cost 1

DSW1(config-if)#no shut

DSW1(config-if)#exit

DSW1(config)#int g1/0/6

DSW1(config-if)#spanning-tree vlan 30 port-priority 64

DSW1(config-if)#no shut

DSW1(config-if)#end

DSW1#copy run start

 

Verification：

DSW1# show spanning-tree vlan 20

DSW1# show spanning-tree vlan 40

DSW2# show spanning-tree vlan 30

That is all, hope to helpful for you. Best Luck for ur BCMSN 642-812 Exam.

If you need the complete pass4sure test questions for 642-812 Exam, you can visit Latest Pass4sure 642-812,maye it helpful for ur exam!

         

33 thoughts on “CCNP BCMSN(642-812) Lab – STP(New)”

  4. I saw this simulation on the 892 composite test today.

    Also Pass4Sure has this as the solution for Vlans 30 and 40

    Int g1/0/6
    sw trunk allow vlan 30
    no shut
    int g1/0/5
    sw trunk allow vlan 40
    no shut
    end

    Now to me tis seems to defeat the purpose of spaning tree alogether. I could not however recall the correct syntax for this solution. The score for the spanning tree section of my test was pretty abysimal so I would think the above post is not correct.

    1. Mr dugger i would like to know whether the solution is correct or not in pass4sure dumps it has been given has
      Int g1/0/6
      sw trunk allow vlan 30
      no shut
      int g1/0/5
      sw trunk allow vlan 40
      no shut
      end
      is the above correct or else in the post it has been given has separe vlans and the cost

      1. in my test, i resolve the lab with the commands port-priority and spanning-tree vlan 20 priority N.

        Although i think kachy’s answer is best for the lab.

        Sorry for my english.

        1. Tips from this page. Switching section

          *Influencing local Root Port election – change the Port Cost.

          *Influencing the Root Port of directly connected downstream switch – change the Port Priority.

  7. I had just finish taking up exam for 642-892,
    their is a problem in this hotspot it doesnt accept the copy run start, pls if any one encounter the same problem let me know, i have already open a case for this bug.

      1. Yes, i had the same problem about the command *copy run start*.

        My teacher say me, *the correct command is copy system:running-config nvram:start-up config*

        i fail in my first test, i got 800/803!!!!!

    2. I havent taken this test yet so not sure if it will help but this is the latest supported command to replace copy run start:

      copy system:running-config nvram:start-up config

  10. (Why Vlan 20 priority 61440)
    The actual question states you have only a lvl 2 access to both the core and DSW2 switches. A show run may not show you details such as spanning tree priorities. So set the priority to the highest ensuring that DSW1 will not be the root for vlan 20.

  11. please why did you use cost 1 for vlan 40 and port priority 64 for vlan 30. And is there any lab on PAgP on the 812 exam. please reply am having my exam this week

  12. DSW1#conf t

    DSW1(config)#spanning-tree vlan 20 priority 61440 <— highest pri wil not be used as ROOT

    DSW1(config)#int g1/0/6
    DSW1(config-if)#spanning-tree vlan 30 port-priority 64 <—- lowered the port-pri from 128 so this will be used to FW traffic
    DSW1(config-if)#no shut
    DSW1(config-if)#end
    DSW1#copy run start

    DSW1(config)#int g1/0/5
    DSW1(config-if)#spanning-tree vlan 40 cost 1 > seems like Cisco just wanted to make sure you know how to manipulate STP (using global priority, port-priority, and cost) .. You may configured it with just cost or priority with same effect, but you may not satisfy the exam objective. =)

  13. oh.. this one.. for the vlan 40..

    DSW1(config-if)#spanning-tree vlan 40 cost 1 You can see in the show stp.. output that most cost defaulted to 19 (this means that the line is a ethernet = 100Meg .. but with cost = 1 you mean you got a 1Gig interface.. the best in this case)

    (I wonder why that was skipped in my earlier post.. =)

    1. Why does Pass4sure use ‘switchport trunk allowed vlan 30’ and ‘switchport trunk allowed vlan 40’ on the gig interfaces instead of using ‘COST’ and ‘PRIORITY’. Is that a legit configuration?

      1. hi Pulsw… about your question..
        the given solution by p4s I blv is also legit..
        coz on the given config .. the gig 1/0/5- 6 are both in trunk mode.. but allowed vlan isnt configured so its passing all vlan in effect..

        WITH the given solution you satisfy the question coz you specify the only VLAN you want to pass in Gig 1/0/5 and gig 1/0/6 ..

        > Well I think as long as you satisfy the question and get the right output in the show spanning-tree .. your answer will be fine.. =)

  14. here is another solution.. a shorter one that is.. I know a friend who passed this exam last month using this solution…

    DSW1#conf t
    DSW1#spanning-tree vlan 20 priority 61440
    DSW1#int gig 1/0/5
    DSW1#spanning-tree vlan 30 port-priority 240
    DSW1#spanning-tree vlan 40 cost 1

    (just ignore the prompt .. just focus on the cmds.. =)

    2. what exactly are we looking for with:

      DSW1# show spanning-tree vlan 20
      DSW1# show spanning-tree vlan 40
      DSW2# show spanning-tree vlan 30

      thanks..

    4. CiscoSky’s example should also works as it is the same principle in terms of adusting port-priority. The original example LOWERS the port-priority of g1/0/6 so that the device at the other end favours that interface for forwarding traffic. CiscoSky’s example does the inverse and INCREASES the priority on g1/0/5 so that the device at the end does NOT favour that interface and instead will use g1/0/6 to forward traffic.

  15. could you tell me which solution is correct
    DSW1(config-if)#spanning-tree vlan 40 cost 1

    DSW1(config-if)#no shut

    DSW1(config-if)#exit

    DSW1(config)#int g1/0/6

    DSW1(config-if)#spanning-tree vlan 30 port-priority 64

    DSW1(config-if)#no shut

    DSW1(config-if)#end

    or

    Int g1/0/6
    sw trunk allow vlan 30
    no shut
    int g1/0/5
    sw trunk allow vlan 40
    no shut

  16. Santosh:

    Use the following config which is the original one in the above lab. ‘SWITCHPORT ALLOWED VLAN’ is another way of doing the same thing. I took the exam today and got 100% in the Spanning Tree category…

    DSW1#conf t

    DSW1(config)#spanning-tree vlan 20 priority 61440

    DSW1(config)#int g1/0/5

    DSW1(config-if)#spanning-tree vlan 40 cost 1

    DSW1(config-if)#no shut

    DSW1(config-if)#exit

    DSW1(config)#int g1/0/6

    DSW1(config-if)#spanning-tree vlan 30 port-priority 64

    DSW1(config-if)#no shut

    DSW1(config-if)#end

    DSW1#copy run start

  17. This lab seems to be prominent in the composite. I tried these commands and it did not work. The only thing I missed was the “no shut”
    The interfaces are already active, why do you require the “no shut”

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