Adding And Removing Ports From Stgs; Switch-Centric Configuration - Lenovo Flex System Fabric CN4093 Application Manual

Adding and Removing Ports from STGs

Switch-Centric Configuration

154
CN4093 Application Guide for N/OS 8.2
 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, trunk groups, VLANs, and Spanning Trees is
shown in Table 18 on page
PVRST is switch‐centric: STGs are enforced only on the switch where they are
configured. The STG ID is not transmitted in the Spanning Tree BPDU. Each
Spanning Tree decision is based entirely on the configuration of the particular
switch.
For example, in Figure
each switch is responsible for the proper configuration of its own ports, VLANs,
and STGs. Switch A identifies its own port 17 as part of VLAN 2 on STG 2, and the
Switch B identifies its own port 8 as part of VLAN 2 on STG 2.
Figure 14. Implementing Multiple Spanning Tree Groups
146.
14, though VLAN 2 is shared by the Switch A and Switch B,