Trunking over Etherchannel

[Kevin Dorrell]

If I want to trunk over Etherchannel, where should the trunk parameters be set up, on the link interfaces (G2/1, G2/2) or on the virtual port interface (Po)?

I notice that I can configure trunk parameters (CDP, allowed VLANs, native VLAN, tag native, etc.) on both the physical links and on the Po interface. Which one takes priority? I notice that if the VLANs allowed on each physical link are not the same, then they will not form an EtherChannel.

Is it necessary at all to configure the trunk parameters on the physical link interfaces? Or is it that if a channel is formed then it uses the Po parameters, and if a channel is not formed then each physical link uses its own parameters?

At the moment I have set up both link interfaces and Po interface in the same way. I am just curious to know the behaviour if they were different.

Kevin Dorrell

Luxembourg

[ankbhasi · Accepted solution]

Hi Kevin,

Long time no see.How are things going.

To put my comments on your query after you configure an EtherChannel, configuration changes applied to the port-channel interface apply to all the physical ports assigned to the port-channel interface.

Configuration changes applied to the physical port affect only the port where you apply the configuration.

To change the parameters of all ports in an EtherChannel, apply configuration commands to the port-channel interface.

Also if the etherchannel is not up then any cofiguration applied to port channel will be having no affect on physical interfaces but if the etherchannel is up then configuration applied to port channel will take care of physical ports.

It is not at all necessary to have all the trunk config on physical link. You can have it on port channel interface and it will take care of physical interface with only necessary condition that etherchannel is up.

HTH

Ankur

[Kevin Dorrell]

Hi Ankur,

Thanks for the reply. That gives me a really good basis to work on. I shall try out some of that in the lab.

I've been a bit busy elsewhere doing CCIE lab exercises from one of the better vendors. So I have been spending time asking questions on NetPro rather than answering them for a change. But I hope to return to NetPro soon, once the lab is all over.

Thanks again.

Kevin.