Duplex setting on Trunk Ports

Unanswered Question
Jan 15th, 2008

Hello all -

I have two 3550's and I have trunking enabled on the fast ethernet ports. I have tried to set both ends to 100/full, however they do not come up. If I go back and set them both to auto/auto they come up. Can I not set trunk ports to 100/full?



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Kevin Dorrell Tue, 01/15/2008 - 05:50

Interesting. I don't see why not. Maybe it has some strange interaction with DTP. How are you forming your trunks, desirable-desirable, desirable-auto, or what? Did the ports come up in access mode, or did they not come up at all?

You could try debug dtp all

Kevin Dorrell


mcechman Tue, 01/15/2008 - 05:56

They are desirable on both ends. If I do a debug dtp all, what would I be looking for? Trunk status?

glen.grant Tue, 01/15/2008 - 07:02

Edison did they have auto-mdix back on the 3550's ? Not sure they did .

glen.grant Wed, 01/16/2008 - 15:41

I have never seen something like this . I would make sure the trunking parameters are exactly alike on both ends . Usuaully though you should get at least a link light , are the patches ok ? When you set it as auto does it autonegotiate 100/full ?


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