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EtherChannel Questions

January 22nd, 2021 Go to comments

If you are not sure about EtherChannel, please read our EtherChannel tutorial.

Question 1

Explanation

In fact answer B is also correct as STP considers Etherchannel links as one physical link so this question should have three correct answers. But answer B is not as obvious as the other two answers so we should choose them.

Answer C is not correct as “Commonly up to 16 links can be assigned to an EtherChannel, but only 8 can be active at a time”.

Reference: https://www.ciscopress.com/articles/article.asp?p=2348266&seqNum=3

So it should be 8 physical ports, not 16.

Question 2

Explanation

The Static Persistence (or “on” mode) bundles the links unconditionally and no negotiation protocol is used. In this mode, neither PAgP nor LACP packets are sent or received.

Question 3

Explanation

From the neighbor status, we notice the “Flags” are SP. “P” here means the neighbor is in Passive mode. In order to create an Etherchannel interface, the (local) SW1 ports should be in Active mode. Moreover, the “Port State” in the exhibit is “0x3c” (which equals to “00111100″ in binary format). Bit 3 is “1” which means the ports are synchronizing -> the ports are working so the local ports should be in Active mode.

Reference: https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3650/software/release/3se/consolidated_guide/command_reference/b_consolidated_3650_3se_cr/b_consolidated_3650_3se_cr_chapter_0100.pdf

Question 4

Question 5

Explanation

In order to configure a Layer 3 EtherChannel, we must use the “no switchport” command and set the IP address on the (logical) port-channel interface. For open-standard EtherChannel protocol we must use LACP with “passive” & “active” mode.

Comments (13) Comments
  1. Anonymous
    April 16th, 2020

    hi people!

    i can’t see questions on this page? Please help me… where they&

  2. Anonymous
    April 20th, 2020

    You have to paid the subscriptions in order to be able to see the questions

  3. Anonymous
    June 9th, 2020

    Does anyone know if these EtherChannel questions come with the exam (2020)?

  4. Anony
    July 17th, 2020

    how can I see the questions?

  5. JD
    September 16th, 2020

    just a quick comment to Q1 explanation:

    In fact STP can block etherchannel, because STP normally operates on this interface, so it is possible that the etherchannel port will be assigned Non-Designated role and will be blocked if some better route to Root Bridge will be available from such switch. So answer B is not correct in any way.

  6. JD
    September 16th, 2020

    I think you misunderstood the “STP does not block physical interfaces bundled into EtherChannel” statement which is true, but STP can block the portchannel interface.

  7. Yasse R YG
    November 29th, 2020

    I appreciate this 9tut, Thanks!

  8. enCrypt
    January 23rd, 2021

    Can someone explain Q4 please? Why would you create the channel group as Active AND Passive?

  9. MoG
    January 27th, 2021

    @enCrypt: You are 100% right at this. It would not make any sense to configure both options. However from this part of the exhibit it is impossible to tell, wether the participating Ports in PortChannel 10 are Active OR Passive. But since they clearly operate in LACP either of these has to be configured.
    TLDR: The formulation of the question is lackluster, but the answeres are right.

  10. Souziana Zagi
    January 7th, 2022

    Question #1
    the correct answers are C and E.
    A is not an option, because to make etherchannel work, we need the same setting on all links including speed, duplex, native VLAN, and correct allowed VLANs list.

  11. donndaryl
    January 10th, 2022

    Hello, I want to no wy the question 3 (Q3) answer is D but not A.

    P: Passive
    A:active

  12. RazakPaul
    January 24th, 2023

    exactly donndaryl still don’t get the explanation

  13. 9tut
    January 25th, 2023

    @donndaryl, @RazakPaul: mode “on” (static “on”) does not belong to LACP while this question clearly stated that it was configured with LACP.

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