Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
An EtherChannel between two switches is configured for LACP. One switch shows the member interfaces as bundled, while the other shows them as individual interfaces. Which explanation is most likely if both sides are using LACP?
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
Best answer
The member interface settings do not match closely enough for bundling, even though both sides use LACP.
This is correct because EtherChannel depends on compatible member settings as well as the protocol.
B
Distractor review
LACP always requires one side to use PAgP as a backup.
This is wrong because LACP and PAgP are different negotiation protocols.
C
Distractor review
EtherChannel cannot operate on switch trunks.
This is wrong because EtherChannel commonly operates on trunk links.
D
Distractor review
One switch must disable STP before EtherChannel can form.
This is wrong because disabling STP is not a requirement for EtherChannel formation.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is believing that simply configuring LACP on both switches guarantees EtherChannel formation. Candidates may overlook the requirement that all member interfaces must have matching settings such as speed, duplex, and VLAN configurations. This leads to one side bundling the interfaces while the other treats them as separate links, causing confusion. The trap exploits the misconception that the negotiation protocol alone controls bundling, ignoring the critical role of interface parameter consistency. Recognizing this distinction is essential to avoid selecting incorrect answers that focus solely on protocol usage without considering interface compatibility.
Technical deep dive
How to think about this question
EtherChannel is a technology that aggregates multiple physical Ethernet links into a single logical link to increase bandwidth and provide redundancy. Cisco supports two main negotiation protocols for EtherChannel: PAgP (Cisco proprietary) and LACP (IEEE standard). LACP dynamically negotiates the formation of the EtherChannel by exchanging LACP Data Units (LACPDUs) between switches to identify compatible interfaces. However, successful bundling depends not only on using the same protocol but also on matching interface characteristics such as speed, duplex mode, VLAN membership, and trunking configuration. When configuring EtherChannel with LACP, both sides must have member interfaces with identical settings. If any parameter differs, such as one side having a different speed or trunk allowed VLAN list, the EtherChannel will not bundle properly. This mismatch causes one switch to show the interfaces as bundled (aggregated), while the other switch treats them as individual interfaces. This behavior occurs because LACP negotiation succeeds in identifying the protocol but fails the consistency checks required for bundling. A common exam trap is assuming that using LACP on both sides guarantees EtherChannel formation regardless of interface settings. In reality, LACP only negotiates the protocol presence; it does not override mismatched interface parameters. Practically, this means network engineers must verify all relevant interface configurations to ensure compatibility. EtherChannel links continue to participate in STP normally, and disabling STP is neither required nor recommended. Understanding this nuance is critical for CCNA candidates troubleshooting EtherChannel issues in Cisco environments.
KKey Concepts to Remember
- EtherChannel bundles multiple physical interfaces into a single logical link to increase bandwidth and provide redundancy between switches.
- LACP (Link Aggregation Control Protocol) negotiates EtherChannel formation by exchanging protocol data units to identify compatible member interfaces.
- Member interfaces must match in speed, duplex, VLAN membership, trunking mode, and other settings for EtherChannel to bundle them successfully.
- If member interface settings differ, one side may bundle interfaces while the other treats them as individual links despite using LACP.
- EtherChannel protocols like LACP require both negotiation compatibility and consistent interface configurations to form a stable channel.
- Switches do not require disabling STP to form EtherChannel; STP runs normally over the logical aggregated link.
- EtherChannel supports both access and trunk ports, allowing aggregated links to carry VLAN traffic when configured as trunks.
- Troubleshooting EtherChannel issues often involves verifying matching interface parameters beyond just the negotiation protocol.
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 interfaces into a single logical link to increase bandwidth and provide redundancy between switches.
What is the correct answer to this question?
The correct answer is: The member interface settings do not match closely enough for bundling, even though both sides use LACP. — The most likely explanation is that some other interface settings do not match, even though both sides are using the same EtherChannel protocol. In practical terms, LACP alone is not enough. The candidate member interfaces also need to agree on characteristics such as speed, duplex, switchport mode, allowed VLANs where relevant, and other channel-related settings. If they do not, one side may treat the links as separate instead of bundling them. This is a common troubleshooting pattern because it tests whether you know that EtherChannel success depends on more than just the negotiation protocol name.
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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