Adding vlans to Cisco 3750

I have two Gig ports configured (trunks) with allowed vlans 100,101 and 200. Each of these belong to port-channel 1.

And I have the same on the other switch.

Question !!! I want to add another vlan. Where do I put it ??

On the physical ports (Gig0/1 and Gig0/2) for both switches ?? On the port-channel for both switches ?? Or on both of the above ?? And if on both of the above, is there any particular order for adding the vlan.

eg the physical first then the port-channel ??

Any feedback appreciated.

Thanks, Joe.

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Could be wrong, but I thought the port channel was simply a logical config where you place the underlying ports that you want to channel. I would guess that you need to add them to the physical ports. I know on the cat side you would add them to the trunk statements for each physical port, and the etherchannel config is left untouched, but never had to do it on a 3750.

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Add them to the Port-Channel, and you'll see in the running configuration that the physical members are modified accordingly.



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Matthew Melbourne

You'd probably have to show configs for what you are trying doing.

Most likely, you only have to edit the allowed vlan list in your trunk definition on your port channel group.

Typicially, your access ports would pick up the VLAN members, anything you do on the physical ports on the port channel group would be ignored.

Reply to
Doug McIntyre

Provided you have a new enough IOS you can just add the VLANs to the Port-channel interface using the 'switchport trunk allowed vlan add ' commannd. Then the VLAN changes will be applied to all physical ports that are members of that particular Port-channel group.

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Schroeder, AJ

Great feedback everyone...thank you. Look's like the majority vote is to make the change on the port- channel. I have hunted high and low for documentation regarding this on the Cisco site. No joy...which doesn't mean to say it does not exist...just I haven't found it.

It does make sense to do the change on the port-channel side (plus the other end) In essence , one change and it filters down to all ports within the group.

What would be interesting if at some stage, the port-channel (for some reason) was removed. I assume then that the ports that were members would loose their dependency on the port-channel and would need to be redefined.

If anyone knows of any docuo regarding this I would be more than delighted.

Thanks agian for everyone's input.

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I usually reference this document if I have questions

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It has proven to be the best starting point for any questions I have.

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Schroeder, AJ Forums website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.