Not able to change auto to trunk mode on switch

[aksher]

SW-B-TOP(config-if)#switchport mode trunk

When trying to execute the above command am getting the following error.

Command rejected: An interface whose trunk encapsulation is "Auto" can not be configured to "trunk" mode.

[glen.grant]

You have to specifically set the encapsulation type first "switchport encapsulation dot1q" then try youir command...

[aksher]

it's not accepting.

SW-B-TOP(config-if)#switchport encapsulation dot1q

^

% Invalid input detected at '^' marker

the model is CGESM.

[jhotles]

You forgot the "TRUNK" portion to the command. It's SWITCHPORT TRUNK ENCAPSULATION DOT1Q

[Fraz Raa]

it was quick thanks for this handy command

[litto]

Thanks a lot.It worked for me

[MarkT102]

Thanks for that. Sometimes I'm a dummy lol.

[Peter Long]

Cisco IOS – An interface whose trunk encapsulation is “Auto” can not be configured to “trunk” mode.

Pete

[glen.grant]

You need to specifically set the encapsulation first , "switchport encapsulation dot1q" then issue your trunk command...

[Julez]

Thanks :)

[Dipaktayde]

specially in cisco 3500 series..

Switch (config-if) # switchport trunk encapsulation ( dot1q | isl )

If you are using cisco use command

#switchport trunk encapsulation isl

#switchport mode trunk

OR ( multi-vendors like hp, juniper & also for cisco)

#switchport trunk encapsulation dot1q

#switchport mode trunk

I hope It helps you

[Dipaktayde]

---

@glen.grant wrote:

You need to specifically set the encapsulation first , "switchport encapsulation dot1q" then issue your trunk command...

---

specially in cisco 3500 series..

Switch (config-if) # switchport trunk encapsulation ( dot1q | isl )

If you are using cisco use command

#switchport trunk encapsulation isl

#switchport mode trunk

OR ( multi-vendors like hp, juniper & also for cisco)

#switchport trunk encapsulation dot1q

#switchport mode trunk

[Julez]

Thank you kindly, you helped in finding a solution to my problem.  :)

[glen.grant]

can you post the config...

[ankurbhasin]

Hi All,

The command which he need to enter first is

"switchport trunk encapsulation dot1q " and then he can confgigure the interface in trunk mode.

So try this command

switch(config)#interface fa0/1

switch(config-if)#switchport trunk encapsulation dot1q

switch(config-if)#switchport mode trunk

and you will be good to go.

HTH, if yes please rate the post.

Ankur