We have 3 core switches connected by 10GBE 5406_1->5412->5406_2
On all 3 there are 2 VLANS 1 and 2.
On 5406_1 there are several ports which are untagged for VLAN2 and now I need to have some ports on 5406_2 that are untagged for VLAN2 which also need to communicate with the ports on 5406_1.
My idea was to have a seccond backbone between the 3 switches that would be untagged for VLAN2. But when we set this up and connect the cables our network grinds to a halt.
Am I going about this in the wrong way? Do I need to disable Tree Spanning?
the 10GB interfaces on all 3 core switches should be configured with VLAN 1 untagged (if used for management) and VLAN 2 tagged. now you can assign untagged ports on your 1GB UTP interfaces (on 5604_1 and 5604_2)
From my experience I would have tagged VLAN 2 on both/all your uplinks between the switches. Untagging should be solely for an end of line device. I would never untag VLANs between switches...
5406_1 (Port A1 (if that's your uplink) tag VLAN 2)->5412 (Port A1-A2 (both your uplink ports) tag VLAN 2)->5406_2 (Port A1 (again if this is your uplink) tag VLAN 2) then untag VLAN 2 on as many ports as you need devices on 5406_2
You do need to have both VLAN's tagged on yur link between switches.
If Vlan 1 is your Primary Vlan then by default all ports will be untagged on Vlan 1.
You then untag ports on Vlan 2 that are going to be used for that vlan only.
Then on Vlan 2 you tag the port(s) that are going to be uplinks to other switches.
Do the same on each of your switches.
You've now got your uplink ports able to carry traffic from both vlan 1 and vlan 2 whilst still keeping the vlans virtually seperate.
Kinda like this:
As you can see all curriculum ports are untagged on Vlan 1. All admin ports are untagged on vlan 2. All uplink ports are Untagged on Vlan 1 and Tagged on vlan 2.