Spanning Tree Protocol
Adding a VLAN to a Spanning Tree Group
If no VLANs exist beyond the default VLAN 1, see the “Creating a VLAN” section in this chapter for information on adding ports to VLANs.
Add the VLAN to the STG using the command /cfg/l2/stp <stg number>/add <vlan number>.
Creating a VLAN
When you create a VLAN, then that VLAN automatically belongs to STG 1, the default STG. If you want the VLAN in another STG, you must move the VLAN by assigning it to another STG.
To move a newly created VLAN to an existing STG:
1.Create the VLAN.
2.Add the VLAN to an existing STG.
When creating a VLAN also consider the following:
•A VLAN cannot belong to more than one STG.
•VLANs that span multiple switches must be mapped within the same Spanning Tree Group (have the same STG ID) across all the switches.
Rules for VLAN tagged ports
Rules for VLAN tagged ports are listed below:
•If a port is tagged, it can belong to multiple STGs.
•When a tagged port belongs to more than one STG, the egress BPDUs are tagged to distinguish the BPDUs of one STG from those of another STG.
•An untagged port cannot span multiple STGs.
Adding and removing ports from STGs
Information on adding and removing ports from STGs is as follows:
•By default, all ports belong to VLAN 1 and STG 1.
•Each port is always a member of at least one VLAN. Each VLAN is always a member of at least one STG. Port membership within VLANs can be changed, and VLAN membership within STGs can be changed. To move a port from one STG to another, move the VLAN to which the port belongs, or move the port to a VLAN that belongs to the STG.
•When you remove a port from a VLAN, that port is also removed from the STG to which the VLAN belongs. However, if that port belongs to another VLAN in the same STG, the port remains in the STG.
•If you remove an untagged port from a
70