Extreme Networks ExtremeWare 7.2e, Installation And User Manual

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STP Rules and Restrictions
ExtremeWare 7.2e Installation and User Guide 213
STP Rules and Restrictions
This section summarizes the rules and restrictions for configuring STP.
•
EMISTP and PVST+ only operate in compatibility mode on the Summit 400. As stated before, a
VLAN can span multiple STPDs. However, on the Summit 400, there is a hardware limitation that
restricts each physical port to a single STPD. If the Summit 400 port is already a member of an STPD,
then that port cannot be in another VLAN that is in a different STPD, or not in a STPD at all.
• The StpdID must be the VLANid of one of its member VLANs, and that VLAN can not be
partitioned.
• A default VLAN can not be partitioned. If a VLAN traverses multiple STP domains, the VLAN must
be tagged.
• An STPD can carry, at most, one VLAN running in PVST+ mode, and its StpdID must be identical
with that VLANid. In addition, the PVST+ VLAN can not be partitioned.
•
The default VLAN of a PVST+ port must be identical with the native VLAN on the PVST+ device
connected to that port.
• If a port supports 802.1w-STPD, then the port must be configured with a default VLAN. If not, the
BPDUs for that STPD are not flooded when the STPD is disabled.
• If an STPD contains both PVST+ and non-PVST+ ports, it must be enabled. If it is disable, the
BPDUs are flooded in the format of the incoming STP port, which may be incompatible with those of
the connected devices.
Configuring STP on the Switch
To configure basic STP, follow these steps:
1 Create one or more STP domains using the following command:
create stpd <name>
NOTE
STPD, VLAN, and QoS profile names must all be unique. For example, a name used to identify a
VLAN cannot be used when you create an STPD or a QoS profile.
2 Add one or more VLANs to the STPD using the following command:
configure stpd <spanning tree name> add vlan <vlan name> {ports <portlist> [dot1d
| emistp | pvst-plus]}
3 Enable STP for one or more STP domains using the following command:
enable stpd {<spanning tree name>}
After you have created the STPD, you can optionally configure STP parameters for the STPD.
NOTE
You should not configure any STP parameters unless you have considerable knowledge and experience
with STP. The default STP parameters are adequate for most networks.