switchport trunk encapsulation not available

Unanswered Question
Dec 5th, 2007

We have a 4510, we do not see or configure the "switchport trunk encapsulation" command on some ports. We have ports on the same blade configured with "switchport trunk encapsulation". But other ports we can't configure? Why is this?

Thanks,

Nick

I have this problem too.
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Hi, you made have to set you port to layer 2 switching mode before you can configuer trunking. Try using the switchport command to change from layer 3 switching.

HTH

switchport

Use the switchport interface configuration command with no keywords on the switch stack or on a standalone switch to put an interface that is in Layer 3 mode into Layer 2 mode for Layer 2 configuration. Use the no form of this command to put an interface in Layer 3 mode.

switchport

no switchport

Use the no switchport command (without parameters) to set the interface to the routed-interface status and to erase all Layer 2 configurations. You must use this command before assigning an IP address to a routed port.

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Note If an interface is configured as a Layer 3 interface, you must first enter this switchport command with no keywords to configure the interface as a Layer 2 port. Then you can enter additional switchport commands with keywords, as shown on the pages that follow.

http://www.cisco.com/en/US/docs/switches/lan/catalyst4500/12.1/12ew/configuration/guide/layer2.html

Edison Ortiz Wed, 12/05/2007 - 16:56

Yes, I've seen that before. Only x amount of ports allows you to configure dot1q or isl while the remaining ports only allow dot1q trunking, hence you don't need to command.

If you post the module number, I can look it up and point you to the problem description.

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