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New Member

VLAN Info

Hi All

I have a small dobut.

There are two L2 switches which are connected to each other through a trunk port.No spanning tree is running in the switch.

I advertise Vlan 1 and Vlan2 on the first trunk link and Vlan 3 and Vlan 4 on the other trunk link.

My question here is what should i do to advertise Valn 3 and Vlan 4 on first trunk link when the second link goes down?

Vijay

9 REPLIES

Re: VLAN Info

Vijay,

Spanning-tree doesn't need to be enabked on the switch and hence will always block one link.

Do you mean to say that you have specifically disabled spanning tree on the switch

can you paste sh spanning tree from both the switches

Narayan

Silver

Re: VLAN Info

If it's only two trunks and two switches, you should probably advertise all four VLANs on both trunk links. This way you will have redundancy in case one of the port will go down.

Re: VLAN Info

Hi

By saying advertise u mean to say that u have allowed vlan 1,2 on the first link,is that so.then in that case STP will take care of forwarding the traffic if one of the links goes down.

Thanks

Mahmood

New Member

Re: VLAN Info

Hi

Thanks for the response.

I have disabled STP on the switch and no Spanning tree is working in this switch.

Both the trunk links are operational and are advertising the vlan info on their respective trunk links.

What if one trunk link goes down?

Is there any way that i can send the Vlan info through the other trunk port.

Vijay

Re: VLAN Info

Vijay,

Unless you prune vlans or remove them from the trunks, all vlans should be transported from all the trunks.

HTH

Narayan

New Member

Re: VLAN Info

Hi

I have pruned the Vlans.

On first trunk port i have allowed Vlans 1 and 2 and on second trunk port i have enabled Vlan 3 and 4.

Vijay

Re: VLAN Info

Hi

It will automatically send the vlan info all trunk links carry traffic for all the vlans.

Can u check what is the status of u r trunk links on both of u r switches and post it.

Thanks

Mahmood

Silver

Re: VLAN Info

If you want redundancy, you will have to enable spanning tree.

Why did you turn it off? What is the reason? If you want user ports to come up really quickly, use "spanning-tree portfast" command

Re: VLAN Info

yes i agree.

you should enable spanning-tree and tweak it to choose one trunk for vlans 1&2 and another for VLANS 3&4

This would take care of redundancy as each trunk will be a backup for 2 vlans

HTH

Narayan

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