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EtherChannel Questions 4

November 22nd, 2019 Go to comments

Question 1

Explanation

For this question please remember this:

The table below lists if an EtherChannel will be formed or not for LACP:

LACP Active Passive
Active Yes Yes
Passive Yes No

The table below lists if an EtherChannel will be formed or not for PAgP:

PAgP Desirable Auto
Desirable Yes Yes
Auto Yes No

To form an Etherchannel both sides must use the same Etherchannel protocol (LACP or PAgP). According the two tables above we can see only “desirable” and “auto” (of PAgP) can form an Etherchannel bundle.

Note: If we want to use “on” mode, both ends must be configured in this “on” mode to create an Etherchannel bundle.

Question 2

Question 3

Explanation

The table below lists if an EtherChannel will be formed or not for PAgP:

PAgP Desirable Auto
Desirable Yes Yes
Auto Yes No

Therefore we can see if one end is in “auto”, the other end must be in “desirable” mode to form an Etherchannel.

Question 4

Question 5

Question 6

Question 7

Question 8

Question 9

Question 10

Explanation

This question would be clear if we have the topology so we drew it here for your reference:

EtherChannel_Load_Balance_2.jpg

Destination MAC address is not correct as this is the MAC address of the server which is always fixed too.

Same for “source and destination MAC address”, it is not suitable either. In general we cannot use any MAC address for load balancing in this topology -> only source IP address is the best choice (as each “customer” has a different source IP address).

The “source MAC address” may be a correct answer as the traffic from R1 can go via one link while R2 can go via the other link if the hashes (using XOR algorithm) on these source MAC addresses are different.

But the option “source IP address” is the best choice here as there are many source IP addresses so the chance of load-balancing is better.

Comments
  1. mimi
    January 8th, 2020

    guys, this question is refering to etherchannels – this means that it needs a L2 method –> src-mac
    SRC-IP is L3 – applies to portchannels!

  2. Maximus
    January 13th, 2020

    Q7.
    Answer should be D & E.

  3. Maximus
    January 13th, 2020

    Q7.
    Correction on my previous comment. B & D are correct. I misunderstood the question earlier. The two command sequences need to entered on different switches. Earlier I thought that you are supposed to enter the same command sequence on the two switches.

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