Alcatel-Lucent 7210 Sas-x Service Manual page 384

Virtual Private LAN Services
Description The bridge-priority command is used to populate the priority portion of the bridge ID field within
outbound BPDUs (the most significant 4 bits of the bridge ID). It is also used as part of the decision
process when determining the best BPDU between messages received and sent. All values will be
truncated to multiples of 4096, conforming with IEEE 802.1t and 802.1D-2004.
The no form of this command returns the bridge priority to the default value.
Default
By default, the bridge priority is configured to 4096 which is the highest priority.
Parameters bridge-priority — The bridge priority for the STP instance.
priority
Syntax priority stp-priority
no priority
Context config>service>vpls>spoke-sdp
config>service>vpls>sap>stp
Description
This command configures the Alcatel-Lucent Spanning Tree Protocol (STP) priority for the SAP.
STP priority is a configurable parameter associated with a SAP. When configuration BPDUs are
received, the priority is used in some circumstances as a tie breaking mechanism to determine
whether the SAPwill be designated or blocked.
In traditional STP implementations (802.1D-1998), this field is called the port priority and has a value
of 0 to 255. This field is coupled with the port number (0 to 255 also) to create a 16 bit value. In the
latest STP standard (802.1D-2004) only the upper 4 bits of the port priority field are used to encode
the SAPpriority. The remaining 4 bits are used to extend the port ID field into a 12 bit virtual port
number field. The virtual port number uniquely references a SAP within the STP instance.
STP computes the actual priority by taking the input value and masking out the lower four bits.The
result is the value that is stored in the priority parameter.
masking out the lower 4 bits results in a parameter value of 0. If a value of 255 is entered, the result is
240.
The no form of this command returns the STP priority to the default value.
Default
128
Parameters stp-priority — The STP priority value for the SAP . Allowed values are integer in the range of 0 to
Page 384
Values
Allowed values are integers in the range of 4096 — 65535 with 4096 being the
highest priority. The actual bridge priority value stored/used is the number entered
with the lowest 12 bits masked off which means the actual range of values is 4096
to 61440 in increments of 4096.
255, 0 being the highest priority. The actual value used for STP priority (and stored in the
configuration) will be the result of masking out the lower 4 bits, thus the actual value range is 0 to
240 in increments of 16.
Default 128
7210 SAS-X, R6 OS Services Guide
For instance, if
a value of 0 is entered,