After an EtherChannel is configured between two Cisco switches, interface port channel 1 is in the down/down state. Switch A is configured with channel-group 1 mode active, while Switch B is configured with channel-group 1 mode desirable. Why is the EtherChannel bundle not working?

A. The switches are using mismatched EtherChannel negotiation modes.

B. The switch ports are not configured in trunking mode.

C. LACP priority must be configured on both switches.

D. The channel group identifier must be different for Switch A and Switch B.








 

Suggested Answer: A

Here we have a situation where one switch is using active mode, which is an LACP mode, and the other is using desirable, which is a PAGP mode. You can not mix the LACP and PAGP protocols to form an etherchannel. Here is a summary of the various etherchannel modes:
 
Reference: http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst2960/software/release/12-2_55_se/configuration/guide/scg_2960/swethchl.html

This question is in 300-115 Implementing Cisco IP Switched Networks (SWITCH) Exam
For getting Cisco Certified Network Professional (CCNP) Routing and Switching Certificate





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