Unable to configure dtp on etherchannel in packet tracer

[john11022]

Hello experts!

I am experimenting with etherchannel and dtp but ran into a problem while trying to configure them for 2 switches. I first connected both switches on interface f0/23 and f0/24 using crossover cable, then bundled interfaces f0/23 and f0/24 into an etherchannel with channel-group 1 mode on, then configured switchport mode dynamic desirable on the port channel interface with int po1. When I ran sh eth sum, everything seemed to work well with the status of po1 being SU and both interfaces being P (bundled).

However, when I ran the sh spanning-tree command it showed (for both switches)

Interface Role Sts Cost Prio.Nbr Type

---------------- ---- --- --------- -------- --------------------------------

Fa0/23 Desg FWD 19 128.23 P2p

Po1 Desg FWD 9 128.27 Shr

Fa0/24 Desg FWD 19 128.24 P2p

and when I ran sh int switchport, po1 seems to be operating in static access, while its administrative mode is dynamic desirable 

Switch#sh int switchport

Name: Po1

Switchport: Enabled

Administrative Mode: dynamic desirable

Operational Mode: static access

Is this a PT bug?

[M02@rt37]

Hello @john11022,

Do you try mode dyn. desirable on one side and dyn. auto on the other side?

[john11022]

I have tried that as well and it yielded the same results

[MHM Cisco World]

dtp is run in physical port not in port channel, 
the port channel must config same as physical ports and both must hardcoded the mode 
access or trunk.

[john11022]

Doesn't configuring the port channel trickle down to the individual ports as well? I configured dynamic desirable on the port channel and when I ran sh int switchport, the administrative mode of the individual ports became dynamic desirable as well, just that the operational mode still remains as static access. And can't I use dynamic desirable on the port channel to let DTP decide whether to use trunking or not?

[MHM Cisco World]

allow vlan1 in trunk and check again, but even with that I dont think DTP work fine in port channel  

[Martin L]

Packet Tracer, aka PT from Cisco Net Academy, is just a software Simulator; it does not run on real IOS or virtual IOS; It is close to IOS but It does not really behave like real IOS would (some simply features do).
PT is excellent tool to learn and practice networking fundamentals and commands for CCNA exam.

Regards, ML
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[paul driver]

Hello

Seems you are only showing one side of the PC
Even though the physical/logical ports are up, which means stp will be active is the trunk actually created, once the trunk is actually active the operational mode should then state TRUNK