KB ID0001167

Problem

If you try and change a ports status, to make it a trunk port, you may see this error;

Petes-Switch(config-if)#switchport mode trunk
Command rejected: An interface whose trunk encapsulation is "Auto" can not be configured to "trunk" mode.

Trunk Settings

I don’t know if this is a throwback to when we had ISL trunking and 802.1q, but you need to specify the encapsulation before you can specify a trunk.

Petes-Switch(config-if)#switchport mode trunk
Command rejected: An interface whose trunk encapsulation is "Auto" can not be configured to "trunk" mode.
Petes-Switch(config-if)#switchport trunk encapsulation dot1q
Petes-Switch(config-if)#switchport mode trunk
Petes-Switch(config-if)#

23 Comments

root2
20/06/2020

gracias
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dkash
01/09/2020

thanks
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mix
16/09/2020

muchas gracias
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Ozkar
02/11/2020

Thank you !!
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Tosin Ayorinde
17/11/2020

Thank you so much. You saved me a lot of stress.
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Julio Castillo
17/12/2020

Thanks A LOT
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onurcanmrngz
01/02/2021

Sagol kardes
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- PeteLong
  01/02/2021
  
  Rica ederim.
  Post a Reply
kuber
01/03/2021

thanks
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mahen
23/04/2021

thankz
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Bian
04/05/2021

Muito Obrigado!
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Sheyson Sanchez
21/05/2021

thanks a lot
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Abudi Al Allaf
27/05/2021

Tackar
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Roman
21/08/2021

Muchas gracias, fue de gran ayuda.
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chasuav
02/09/2021

Thank you!
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Rfven
28/12/2021

Muchas gracias!!
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irfan
18/01/2022

tq from Indonesia
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kilian
23/02/2022

merci
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patricio
14/07/2022

gracias
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Sampson
04/09/2022

Thanks
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marco
24/09/2022

muchas gracias bro
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Vincent
15/02/2023

Thanks I had forgotten.
Post a Reply
S Barry
04/04/2023

Thank you – I can’t believe I forgot this!
It is indeed an old ISL throughback!
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Cisco IOS – An interface whose trunk encapsulation is “Auto” can not be configured to “trunk” mode.

Problem

Trunk Settings

Related Articles, References, Credits, or External Links

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