Encapsulation on sub-interface

Unanswered Question
Mar 27th, 2007

Is there any possibility to enable encapsulation on 3550 switch's fa subinterface mode? I have donw the same on 3660 Router, but it's not running on 3550 switch.

Any comments?

I have this problem too.
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Amit Singh Tue, 03/27/2007 - 10:23

No, you cannot use that. Encapsulation is not supported on layer 3 switch sub-interfaces. Its is only supported on the Layer 2 ports.

HTH,Please rate if it does.

-amit singh

Richard Burts Tue, 03/27/2007 - 10:26


I do not believe that you can do subinterfaces on the fastethernet of a 3550. The fastethernet interfaces are already layer 2 capable interfaces which can be access or can be trunk. On the 3660 router the fastethernet is a layer 3 interface and you do subinterfaces to be able to process trunk connections. On the 3550 you process the trunk connection directly on the fastethernet interface.



ankbhasi Tue, 03/27/2007 - 10:50

Hi Rick,

3550 being a layer 3 switch we can issue "no switchport" command on any of the fast ethernet interfaces and it will start working as a layer 3 port.

Then it will also support sub-interface commnd but will not support encapsulation command. The reason it supports subinterface command is beacause the IOS on 3550 is based on normal IOS base train which allows this command but encapsulation is not supported in hardware.




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