Etherchannel between 2950G and 3524XL

Unanswered Question

Hi there,

We are running 2 switches at different locations:
2950G  ISO  12.1(22)EA4
3524XL IOS  12.0(5)

Between them are 2 100Mbps  LanX lines with 2 different providers.

The etherchannel seems to  come up OK, but only one of the lines is used.  I cannot see the other  ends of the etherchannel setup via CDP.

My questions are:
1.  Is  CDP required for this to work?
2.  If not, is it difficult to make  it work without CDP?
3.  If it does work without CDP, does that  compromise the complete functionality of the setup?

Thanks for  any help you can offer.


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Giuseppe Larosa Sun, 03/21/2010 - 05:47

Hello Frank,

>> but only one of the lines is used.

unfortunately C2950 supports etherchannels only in this limited way with second link that is only an hot standby.

They provide redundancy but not load sharing over the bundle.

We had even opened a Cisco service request when we have seen this on a C2950LRE but  we had this feedback.

It is not a question of CDP but of switch real capabilities

>> I cannot see the other  ends of the etherchannel setup via CDP.

this depends from service provider configuration if they use 802.1 Q inQ tunneling they need to enable L2 tunneling protocol in order to carry CDP frames over the point to point service.


as you can see transport of CDP, VTP and STP can be enabled by service provider or not

Hope to help


Giuseppe Larosa Tue, 03/23/2010 - 08:07

Hello Frank,

who is on the other side of the bundle is not a problem

I couldn't find an exact reference but as I wrote we got this answer in a Cisco TAC Service Request for 2950 LRE

Hope to help



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