Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
Exhibit
SW1# show etherchannel summary Group Port-channel Protocol Ports ------+-------------+-----------+----------------------------------------------- 1 Po1(SD) LACP Gi0/1(I) Gi0/2(I) SW2# show etherchannel summary Group Port-channel Protocol Ports ------+-------------+-----------+----------------------------------------------- 1 Po1(SU) LACP Gi0/1(P) Gi0/2(P)
A port-channel between two switches is not forming correctly. Based on the output, what is the most likely cause?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Distractor review
SW2 must switch from LACP to PAgP.
This is wrong because there is no evidence that PAgP is required here.
B
Distractor review
Po1 is down on SW2 because the S flag means suspended.
This is wrong because SW2 shows `Po1(SU)`, not a failed state.
C
Distractor review
The EtherChannel protocol types are mismatched between the switches.
This is wrong because both outputs explicitly show LACP.
D
Best answer
The links on SW1 are not bundling into the channel, while SW2 believes the bundle is up.
This is correct because the exhibit shows SW1 member interfaces marked `(I)`, meaning they are operating individually instead of as part of the bundle.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A common exam trap is assuming that a port-channel failure is caused by a protocol mismatch or that the port-channel is down on both switches. In this scenario, both switches use LACP, so the protocol matches. The trap is misreading the interface flags: interfaces marked (I) on one switch indicate they are not bundled, while the other switch shows (P), meaning it believes the bundle is up. This mismatch causes the EtherChannel not to form properly, but the trap is to overlook the significance of these flags and jump to incorrect conclusions about protocol or link failures.
Technical deep dive
How to think about this question
EtherChannel is a technology that bundles multiple physical Ethernet links into a single logical link to increase bandwidth and provide redundancy. Cisco switches support EtherChannel using protocols like LACP (Link Aggregation Control Protocol) and PAgP (Port Aggregation Protocol) to negotiate and maintain the bundle. Each member interface must be correctly configured and synchronized to participate in the port-channel group, ensuring consistent link aggregation across devices. When troubleshooting EtherChannel issues, it is crucial to verify that both ends use the same aggregation protocol and that member interfaces are properly bundled. The port-channel interface status and member interface flags provide insight into the bundle state. For example, interfaces marked with (P) indicate active participation in the bundle, while (I) means the interface is operating individually and not bundled. A mismatch in these states between switches causes the EtherChannel to malfunction. A common exam trap is misinterpreting the port-channel and member interface flags, leading to incorrect assumptions about protocol mismatches or interface failures. In practice, one switch may believe the bundle is up while the other has not bundled the links, causing traffic disruption. Understanding the meaning of status flags like (I) for individual and (P) for bundled interfaces helps avoid this confusion and correctly diagnose EtherChannel problems.
KKey Concepts to Remember
- EtherChannel bundles multiple physical links into a single logical interface to increase bandwidth and provide redundancy between switches.
- LACP and PAgP are negotiation protocols that must match on both ends for EtherChannel to form correctly.
- Member interfaces marked with (P) indicate they are actively bundled in the port-channel, while (I) means the interface is operating individually.
- A port-channel interface status of (SD) means the port-channel is down and the member interfaces are suspended or not bundled.
- Both switches must agree on the EtherChannel protocol and bundle membership for the port-channel to become operational.
- Misinterpretation of interface flags can lead to incorrect troubleshooting conclusions about protocol mismatches or interface failures.
- EtherChannel inconsistencies often arise when one switch bundles links correctly but the other switch’s interfaces remain individual.
- Correctly reading port-channel and member interface states is essential for diagnosing EtherChannel formation issues in Cisco networks.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
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More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A router learns the same prefix from both OSPF and EIGRP. Which route is installed by default?
Question 2
A router shows this output: R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.1.1.2 1 FULL/DR 00:00:34 192.168.12.2 GigabitEthernet0/0 10.1.1.3 1 2WAY/DROTHER 00:00:39 192.168.12.3 GigabitEthernet0/0 Which statement is correct?
Question 3
What is the OSPF metric called?
Question 4
A non-root switch has two uplinks toward the root bridge. One path has a lower total STP cost than the other. What role will the lower-cost uplink have?
Question 5
A router interface applies this ACL inbound: 10 deny tcp any any eq 80 20 permit ip any any A user reports that web browsing to a server by IP address fails, but ping works. Which statement best explains the behavior?
Question 6
A router learns route 198.51.100.0/24 from OSPF with AD 110 and also has a static route to the same prefix configured with AD 150. Which route is installed?
FAQ
Questions learners often ask
What does this 200-301 question test?
EtherChannel bundles multiple physical links into a single logical interface to increase bandwidth and provide redundancy between switches.
What is the correct answer to this question?
The correct answer is: The links on SW1 are not bundling into the channel, while SW2 believes the bundle is up. — The output shows an inconsistency between the two switches. On SW2, the port-channel appears up and the member interfaces are marked with `(P)`, which means they are participating in the bundle. On SW1, the port-channel is shown as `Po1(SD)` and the member links are marked `(I)`, indicating they are stand-alone and not bundled. In simple terms, SW2 thinks the team is formed, but SW1 has not actually joined the links into the team. That tells you the problem is not a protocol mismatch, because both sides are using LACP. The interpretation question is really about reading the state flags correctly.
What should I do if I get this 200-301 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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