Allied Telesis SwitchBlade x3100 Series Manual page 489

STP Configuration with UFO VLAN
When a ring topology is implemented in the user's network, the user may not be aware of which ring ports are
designated primaryupstream and which are designated downstream. Therefore, if the user wants to configure clas-
sifiers on these ring ports, they should apply them to both ring ports. This ensures that the traffic classification
required by the user is actually applied.
This restriction strictly applies only to the switches which actually make up the ring. The aggregating layer 2
switch or any switch above it could be the root bridge for a ring network. These are configured as follows:
If the aggregating layer 2 switch is an SBx3112 and does become the root bridge then the
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parameter for the ports as shown above cannot be set to STP. The upstream port from the aggregating
layer 2 switch, which is the real network uplink for such a configuration, should be set to PRIMARYUP-
STREAM and the other two links which make up the ring must be set to DOWNSTREAM.
If the aggregating layer 2 switch is an SBx3112 and not the root bridge but one of the switches above it is,
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then the FORWARDING parameter can be set to STP and the status of the ports will be determined with
STP's assistance similar to the other switches in the ring.
To implement a ring topology, interfaces must be configured as ring interfaces. This allows the STP protocol to
determine the exact upstream and downstream ports. This provisioning is accomplished using the SET VLAN
command. Refer to the
Software Reference for SwitchBlade x3100 Series Switches (Layer Two Switching)
SET VLAN INTERFACE command.
Introduction
FORWARDING
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