Adding And Removing Ports From Stgs - Lenovo ThinkSystem NE2552E Application Manual

Adding and Removing Ports from STGs

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 When you add a port to a VLAN that belongs to an STG, the port is also added
to that STG. However, if the port you are adding is an untagged port and is
already a member of another STG, that port will be removed from its current
STG and added to the new STG. An untagged port cannot belong to more that
one STG.
For example: Assume that VLAN 1 belongs to STG 1, and that port 1 is untagged
and does not belong to any STG. When you add port 1 to VLAN 1, port 1 will
automatically become part of STG 1.
However, if port 5 is untagged and is a member of VLAN 3 in STG 2, then
adding port 5 to VLAN 1 in STG 1 will not automatically add the port to STG 1.
Instead, the switch will prompt you to decide whether to change the PVID from
3 to 1:
"Port 5 is an UNTAGGED/Access Mode port and its current PVID/Native
VLAN is 3.
Confirm changing PVID/Native VLAn from 3 to 1 [y/n]:" y
 When you remove a port from VLAN that belongs to an STG, that port will also
be removed from the STG. However, if that port belongs to another VLAN in the
same STG, the port remains in the STG.
As an example, assume that port 2 belongs to only VLAN 2, and that VLAN 2
belongs to STG 2. When you remove port 2 from VLAN 2, the port is moved to
default VLAN 1 and is removed from STG 2.
However, if port 2 belongs to both VLAN 1 and VLAN 2, and both VLANs
belong to STG 1, removing port 2 from VLAN 2 does not remove port 2 from
STG 1, because the port is still a member of VLAN 1, which is still a member of
STG 1.
 An STG cannot be deleted, only disabled. If you disable the STG while it still
contains VLAN members, Spanning Tree will be off on all ports belonging to
that VLAN.
The relationship between port, LAGs, VLANs and Spanning Trees is shown in
Table 18 on page 175.
Chapter 10: Spanning Tree Protocols
183