Exam 300-115 topic 1 question 82 discussion

Actual exam question from Cisco's 300-115

Question #: 82
Topic #: 1

[All 300-115 Questions]

Refer to the exhibit.

Which EtherChannel negotiation protocol is configured on the interface f0/13 f0/15?

A. Link Combination Control Protocol
B. Port Aggregation Protocol
C. Port Combination Protocol
D. Link Aggregation Control Protocol

Show Suggested Answer

Suggested Answer: B 🗳️
PAgP modes are off, auto, desirable, and on. Only the combinations auto-desirable, desirable-desirable, and on-on will allow a channel to be formed. .
1. on: PAgP will not run. The channel is forced to come up.
2. off: PAgP will not run. The channel is forced to remain down.
3. auto: PAgP is running passively. The formation of a channel is desired; however, it is not initiated.
4. desirable: PAgP is running actively. The formation of a channel is desired and initiated.
The Link Aggregate Control Protocol (LACP) trunking supports four modes of operation:
✑ On: The link aggregation is forced to be formed without any LACP negotiation .In other words, the switch neither sends the LACP packet nor processes any inbound LACP packet. This is similar to the on state for PAgP.
✑ Off: The link aggregation is not formed. We do not send or understand the LACP packet. This is similar to the off state for PAgP.
✑ Passive: The switch does not initiate the channel but does understand inbound LACP packets. The peer (in active state) initiates negotiation (when it sends out an LACP packet) which we receive and answer, eventually to form the aggregation channel with the peer. This is similar to the auto mode in PAgP.
✑ Active: We can form an aggregate link and initiate the negotiation. The link aggregate is formed if the other end runs in LACP active or passive mode. This is similar to the desirable mode of PAgP.
In this example, we see that fa 0/13, fa0/14, and fa0/15 are all in Port Channel 12, which is operating in desirable mode, which is only a PAgP mode.

by Bastex at Nov. 6, 2019, 11:58 a.m.

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GuramM

5 years, 7 months ago

There is NO Correct answer in the options. In protocol tab we see no LACP and no PAGP we see there is - and it means its static/manual link aggregation. Missing correct Option or Wrong Picutre

upvoted 3 times

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Bastex

5 years, 7 months ago

Desirable mode of trunking has no to do with PAgP desirable mode. So there is no correct answer. We have either wrong picture or wrong options list.

upvoted 2 times

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