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.
Explanation:
Port Aggregation Protocol (PAgP) Modes
Desirable Auto
Desirable Yes Yes
Auto Yes No
Link Aggregation Control Protocol (LACP)
Active Passive
Active Yes Yes
Passive Yes No
EtherChannel “on” mode
EtherChannel “on” mode makes the interface into an EtherChannel without any negotiation protocols like Port Aggregation Protocol (PAgP) or Link Aggregation Control Protocol (LACP). When using a EtherChannel “on” mode, EtherChannel will be created only when another interface group in EtherChannel “on” mode.
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Port Aggregation Protocol (PAgP) Modes
Desirable + Auto = yes
Desirable + Desirable = Yes
Auto + Auto = No
Link Aggregation Control Protocol (LACP)
Active + Passive = yes
Active + Active = yes
Passive + Passive = No
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