I deployed a new cisco 9500 to be trunk to cisco WS-C3560-24PS. However, on the WS-C3560-24PS when I tried to remove the switchport trunk encapsulation dot1q. I get Command rejected: A port which is configured to "trunk" mode can not be configured to negotiate the encapsulation. Please if any one can share some light.
I don't think you can use encapsulation ISL anymore; so only one left is encapsulation dot1q along with switchport mode trunk - which i think you must have it on trunk port. You can try command switchport nonegotiate.
you must remove switchport mode trunk first - worked for me but not the same switch
why you want to remove that command ?
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Well I don't want to encapsulate. I know we can only use sot1q, but that's the thing I want to remove that statement. I have other switches connect to the same cisco 9500 just as trunk and vlan allowed. However, if I remove switchport mode trunk first I may lose the trunk I'm not local to the switch, but I also tried to console to the switch without success. I think I will try what you are recommending.
not sure what kind of IOS Code running here :
check this example :
it would be nice to see the configuration and explain - how the other side configured, what is not working exactly.
on the beginning. I wasn't able to console, but I rebooted the switch I default int gig 0/1, However, the switch keep forcing me to use dot1q. All I need is switchport trunk allowed vlan xxx, xxx,xxx and switchport mode trunk. because the cisco 9500 which is connect doesn't have choice for dot1q at the interface level. but I replace the switch with 3650 and that fixed the issue.