Alteon Application Switch Operating System Application Guide
Spanning Tree Protocol
Document ID: RDWR-ALOS-V2900_AG1302
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Adding a VLAN to a Spanning Tree Group
•
If no VLANs exist beyond the default VLAN 1, see
for information on
adding ports to VLANs.
•
Add the VLAN to the STG using the
/cfg/l2/stg
<stg-#>
/add
<vlan-number>
command.
Creating a VLAN
•
When you create a VLAN, that VLAN 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.
Move a newly created VLAN to an existing STG by following this order:
a. Create the VLAN
b. Add the VLAN to an existing STG
•
If ports are tagged, all trunked ports can belong to multiple STGs.
•
A port that is not a member of any VLAN cannot be added to any STG. The port must be added
to a VLAN, and that VLAN added to the desired STG.
Rules for VLAN-Tagged Ports
•
Tagged ports can belong to more than one STG, but untagged ports can belong to only one STG.
•
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 to and from STGs
This section includes the following sub-sections:
•
•
•
Adding a Port
When you add a port to a VLAN that belongs to an STG, the port is also added to the STG. However,
if the port you are adding is an untagged port and is already a member of an STG, that port is not
added to an additional STG because an untagged port cannot belong to more that one STG.
Example
VLAN1 belongs to STG1. You add an untagged port, port 1, that does not belong to any STG to
VLAN1, and port 1 becomes part of STG1.
If you add untagged port 5 (which is a member to STG2) to STG1, Alteon prompts you to change the
PVID from 2 to 1:
"Port 5 is an UNTAGGED port and its current PVID is 2. Confirm changing PVID
from 2 to 1 [y/n]:" y
