Original subtitles

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So what happens when we set 1 side to manual trunking

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so int g0/0 switchport mode trunk

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notice we have to specify an encapsulation

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so switchport trunk encapsulation sot1q switchport mode trunk

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So I’ve manually configured switch 1 to use trunking

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so sh int g0/0 switchport

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so this side is configured as a trunk

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and is operating as a trunk using 802.1Q

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on this switch sh interface trunk

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notice it's negotiated to use trunking with 802.1Q

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so its currently trunking even though this side was configured for auto.

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So sh int g0/0 switchport

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This was configured to use DTP or dynamic auto mode

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but it became a trunk because the switch on the left was configured as a trunk.

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So if you configure 1 side manually

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the other side will automatically be configured as a trunk when DTP is used

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when this side is configured as an access port

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so sh int g0/0 switchport

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Notice it was statically configured as an access port

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and is operating as an access port.

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Negotiation of trunking is off on this side

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it’s dynamically configured to use auto

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but the operational mode has become static access.

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So if 1 side is configured as a trunk statically and the other side is configured

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to use either dynamic auto or dynamic desirable a trunk will be formed

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but if 1 side is statically configured as an access port.

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The DTP side will become an access port.

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So the switch can dynamically be configured with the right mode.

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you can have a problem where 1 side is configured as access

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and 1 side is configured as a trunk port

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so you need to either manually configure both sides as a trunk

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or manually configure both sides as access or use DTP.

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The recommendation is that you manually configure both sides and turn off DTP

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So what we will do is do something like this on gigabit 0/0

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we’ve configured the encapsulation as dot1q, it’s an access port

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but to configure trunking, we type switchport mode trunk

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and we would type switchport nonegotiate to disable DTP.

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So this is the recommended configuration.

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Set your encapsulation to dot1q

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set the mode to trunking manually or statically and disable DTP

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Now we have to do that on both sides.

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So on this side, we will do something similar

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sh int g0/0 trunk

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notice gigabit 0/0 is configured as a trunk

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it’s configured manually or statically, so the mode is on.

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It’s currently trunking with the native VLAN set to 1.