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Specifications

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368 ExtremeWare XOS 10.1 Command Reference Guide
STP Commands
• Within any given STPD, all VLANs belonging to it use the same spanning tree.
Member VLANs
When you add a VLAN to an STPD, that VLAN becomes a member of the STPD. The two types of
member VLANs in an STPD are:
• Carrier
• Protected
Carrier VLAN. A carrier VLAN defines the scope of the STPD which includes the physical and logical
ports that belong to the STPD and the 802.1Q tag used to transport EMISTP or PVST+ encapsulated
BPDUs. Only one carrier VLAN can exist in a given STP domain although some of its ports can be
outside the control of any STP domain at the same time.
NOTE
The carrier VLAN’s StpdID must be identical to the VLANid of one of the member VLANs in that STP
domain.
Protected VLAN. Protected VLANs are all other VLANs that are members of the STP domain but do
not define the scope of the STPD. These VLANs “piggyback” on the carrier VLAN. Protected VLANs do
not transmit or receive STP BPDUs, but they are affected by STP state changes and inherit the state of
the carrier VLAN. Protected VLANs can participate in multiple STP domains, but any particular port in
the VLAN can belong to only one STP domain. Also known as non-carrier VLANs.
STPD Modes
An STPD has two modes of operation:
• 802.1d mode
Use this mode for backward compatibility with previous STP versions and for compatibility with
third-party switches using IEEE standard 802.1d. When configured in this mode, all rapid
configuration mechanisms are disabled.
• 802.1w mode
Use this mode for compatibility with Rapid Spanning Tree (RSTP). When configured in this mode,
all rapid configuration mechanisms are enabled. The benefit of this mode is available on
point-to-point links only.
RSTP is enabled or disabled on a per STPD basis only. You do not enable RSTP on a per port basis.
By default, the:
• STPD operates in 802.1d mode
• Default device configuration contains a single STPD called s0
• Default VLAN is a member of STPD s0 with autobind enabled
All STP parameters default to the IEEE 802.1d values, as appropriate.