Vlan – Blocking all VLANs between Juniper switches

juniper-exspanning treevlan

I have some Juniper switches (Model: ex4550-32f) connected together with trunk ports.

I want to allow VLAN 6 on all below interfaces because it is the main switch and connected to other switches in other locations with one connection only. Why it is blocked on some interfaces? How can I solve it?

You can see the results below:

J**U-MAIN-CORE-SW# run show spanning-tree interface vlan-id 6
Spanning tree interface parameters for instance 0
Interface    Port ID    Designated      Designated         Port    State  Role
                         port ID        bridge ID          Cost
xe-0/0/0.0     128:513      128:513  32768.5c4527ddd701      2000  FWD    DESG
ge-0/0/1.0     128:514      128:514  32768.5c4527ddd701     20000  BLK    DESG
xe-0/0/2.0     128:515      128:515  32768.5c4527ddd701      2000  BLK    DESG
xe-0/0/27.0    128:540      128:540  32768.5c4527ddd701      2000  BLK    DESG
xe-0/0/31.0    128:544       128:53  32769.6899cd9eed00      2000  FWD    ROOT**

Best Answer

It's blocked on some ports because this switch is not the root switch for that VLAN. The root switch for VLAN 6 is connected (directly, or through another switch) to port xe-0/0/31.0.

If you want this switch to be the root switch, you need to lower the Bridge ID. You left the priority at the default of 32768. I assume you left all the switches at the default, and the root bridge will be determined by the lowest MAC address. You should lower the priority to determine the root, otherwise the determination is left to the lowest MAC address.