Vlan Cascade without trunk port

[emi91]

Hi Guys,

Actually I'm working to a new configuration on our system. We have a lots of devices that has a redundant link (Primary and Secondary).

We have a fews rack mount system devices connected to a single switch using the vlan (Vlan #100 Primary and Vlan #200 Secondary).

Now I would like to connect these vlans to a two switches that has not vlan configuration: we use one switch for Primary and one switch for Secondary.

Now the problem is: If I connect one rack system (any rack) to these switches without vlan configuration we don't have any problems and the system works well, instead if I connect two rack in this way I lost the secondary link to one of the rack system.

Another problem is, If I connect just one rack to the switches all works properly, but If I disconnect and reconnect the secondary link, the primary link goes down for a few seconds and after turn up. This is strange because you should be able to connect and disconnect secondary link without interere with primary link.

All the ports on the rack switches are configured to access port and assigned to a respectively vlan.

I attached an image to show you better my set-up.

Thank you for your help and suggest.

Emi

[MHM Cisco World]

Vswitch and device' this part not clear.

How device have primary in one vlan and secondary in other vlan ?

[emi91]

Hi,

All the devices have two separate NIC one for Primary link and one for Secondary link. 

[MHM Cisco World]

Yes but how you config vNIC in device l2 or l3 ?

[emi91]

L2 Vlan

[MHM Cisco World]

Friend this will not work I think.

Sorry 

Both primary and secondary l2 must be in same vlan access port or trunk allow same vlan.

[emi91]

Are you suggest me to connect in the same vlan both primary and secondary or to have all the primary link in one vlan and secondary link in another vlan? in fact create vlans for all switches and not just for a few switches?

I'm sorry probably I don't explain well the system.

Primary and Secondary must be in a separate Lan. What I would like to do is to use one switch with a few devices that I need to connect and use it as necessary. I just want to have a redundancy for the cables and not for the switch, and this is why I created a Vlan. 

I have problems with these two Vlan switches just when I connect both in the same system, like I draw in attached image. 

I'm not an expert, I just suspect something going wrong with Vlan ID maybe? I'm not really sure this should be the right way to create this "hybryd" system.

Thank you for you help

[MHM Cisco World]

Dont use primary and secondary vNIC devices and share result.

Use only primary.

[emi91]

If I use only primary everything works well. And works well too if I connect the vlan#2 (secondary link) of one switch

[MHM Cisco World]

I know I ask a lot 
can you mention in your original draw what is connection work fine 
thanks 

[Flavio Miranda]

Hi @emi91 

 Probably the spanning-tree is bloking on link which would be an expected behavior.

 When you disconnect the primary and connect the secondary, the time out you see is spanning-tree recalculation

[emi91]

Hi,

I suspect them but I disabled the spanning tree protocol.

You think STP can create problems when I connect the two vlans of both switches together to the "master switch" primary and secondary?

thank you

[Flavio Miranda]

Do you have connection between primary and secondary switch?

 Spanning-tree does not creste problem but it will eliminate redundant path to avoid loop.

[emi91]

No, primary and secondary are two separately LAN. Any loop can be create. It’s all Dante interface.

[emi91]

Hi Flavio,

After a double check I show that the STP was activate. I disabled it and everything works well. But now, I'm not so expert to understand, could you please explain me why, without any loop, the STP create this problems? maybe the Vlan#2 has a tag and when I connect both vlans#2 to the secondary switch STP block one of the two switch? there's some configuration to do for keep STP active?

Thank again for your help