trunk mode auto

Unanswered Question
Jul 29th, 2008

hi everybody!

i just want to know if two switches sw1 and sw2 are connected as:


f0/1 f0/2

will the trunk form if sw1 is configured as:

sw1(config-if)switchport mode dynamic auto

sw2 is configured as:

sw2(config-if)switchport trunk encapsulation dot1q

sw2(config-if)switchport mode trunk

i did not turn off the dtp on sw2.

According to cisco document, trunk will form if the combination is dynamic auto and "trunk" . Is it because dtp is not turned off and sw1 configured with dynamic auto receives the dtp packets and form the trunk? if yes that means if i turn off dtp on sw2 , the trunk should not form ,given that sw1 has dynamic auto configured while sw1 has mode " trunk" ?]

thanks a lot!

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Giuseppe Larosa Tue, 07/29/2008 - 12:50

Hello Sarah,

your understanding is correct.

only if the sw2 use the nonegotiate option the trunk will not form on sw1 side

Hope to help



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