Home > EtherChannel Questions

EtherChannel Questions

February 6th, 2017 Go to comments

Question 1

Explanation

The way EtherChannel load balancing works is that the switch assigns a hash result from 0-7 based on the configured hash method ( load balancing algorithm ) for the type of traffic. This hash result is commonly called as Result Bundle Hash (RBH).

Now we need to convert Load value from Hexadecimal to Binary numbers. Therefore:
+ Gi1/1: 36 (Hex) = ‭00110110‬ (Bin) -> Bits 3, 4, 6, 7 are chosen
+ Gi1/2: 84 (Hex) = ‭10000100‬ (Bin) -> Bits 1, 6 are chosen
+ Gi1/3: 16 (Hex) = ‭00010110‬ (Bin) -> Bits 4, 6, 7 are chosen

Therefore if the RBH is 3, it will choose Gi1/1. If RBH is 4, it will choose Gi1/1 and Gi1/3 interfaces. If RBH is 6 it will choose all three above interfaces. And the bit sharing ratio is 3:3:2 (from “No of bits” column) hence two links has higher probability of getting utilized as compared to the third link.

Question 2

Question 3

Explanation

All interfaces in an EtherChannel must be configured identically to form an EtherChannel. Specific settings that must be identical include:
+ Speed settings
+ Duplex settings
+ STP settings
+ VLAN membership (for access ports)
+ Native VLAN (for trunk ports)
+ Allowed VLANs (for trunk ports)
+ Trunking Encapsulation (ISL or 802.1Q, for trunk ports)

Question 4

Explanation

LACP is the IEEE Standard (IEEE 802.3ad) and is the most common dynamic Etherchannel protocol, whereas PAgP is a Cisco proprietary protocol and works only between supported vendors and Cisco devices.

Comments (5) Comments
  1. Tomorrow Exam
    April 10th, 2017

    What is the status of port-channel if LACP is misconfigured?

    A. Forwarding
    B. Enabled
    C. Disabled
    D. Errdisabled

    Hi can you please explain why C is the answer and not D

  2. Abdullah
    April 10th, 2017

    @Tomorrow Exam the answer is C which is Disabled

  3. Dude
    April 13th, 2017

    @9Tut what is the correct answer for 4th question is it Disabled state or Errordisabled state.

  4. jabs
    May 8th, 2017

    Torrow exams, the Errdisabled is a port-security violation state, which you will get when you configure port security with security violation on a switchport.. The etherchannel port will be disabled if the parameters of LACP configuration are not met at both ends.. Exam when bot end of the link are configure with passive, the LACP link is disabled.. so we have port status in LACP as diasbled, Passive, Active en on. where on-on will active the link, Active-passive will activate the link .

  5. San
    May 24th, 2017

    Can someone explain this

    Refer to the exhibit. While troubleshooting a switch, you executed the “show interface port-channel 1 etherchannel” command and it returned this output. Which information is provided by the Load value?
    Etherchannel_show_interface_port-channel.jpg

    A. the percentage of use of the link
    B. the preference of the link
    C. the session count of the link
    D. the number source-destination pairs on the link