HP 5400ZL - Manual (Page 172)

Multiple Instance Spanning-Tree Operation
Configuring MSTP
Operating Notes for the VLAN Configuration Enhancement
■ Configuring MSTP on the switch automatically configures the
Internal Spanning Tree (IST) instance and places all statically and
dynamically configured VLANs on the switch into the IST instance.
The spanning-tree instance vlan command creates a new MST
instance and moves the VLANs you specify from the IST to the MSTI.
You must map a least one VLAN ID to an MSTI when you create it. You
cannot map a VLAN ID to more than one instance. You can create up to
16 MSTIs in a region.
■ The no form of the spanning-tree instance vlan command removes one
or more VLANs from the specified MSTI. If no VLANs are specified,
the
no form of the command deletes the specified MSTI.
When you remove a VLAN from and MSTI, the VLAN returns to the IST
instance, where it can remain or be re-assigned to another MSTI config­
ured in the region.
■ If you enter the spanning-tree instance vlan command before a static
or dynamic VLAN is configured on the switch to preconfigure VLAN
ID-to-MSTI mappings, no error message is displayed. Later, each
newly configured VLAN that has already been associated with an
MSTI is automatically assigned to the MSTI.
This new default behavior differs from automatically including configured
(static and dynamic) VLANs in the IST instance and requiring you to
manually assign individual static VLANs to an MSTI.
■ The valid VLAN IDs that you can map to a specified MSTI are from 1
to 4094. The VLAN ID-to-MSTI mapping does not require a VLAN to
be already configured on the switch. The MSTP VLAN enhancement
allows you to preconfigure MSTP topologies before the VLAN IDs
associated with each instance exist on a switch.
■ When you use preconfigured VLAN ID-to-MSTI topologies, ensure
that MSTP switches remain in the same region by mapping all VLAN
IDs used in the region to the same MSTIs on each regional switch.
■ When you upgrade switch software to release K.13.XX and later, the
existing MSTP topology configuration is automatically saved. All
existing VLAN ID-to-MSTI assignments are maintained on a switch
for uninterrupted MSTP network operation.
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