Alcatel-Lucent 7210 SAS M Service Manual page 407

priority
Syntax priority stp-priority
no priority
Context config>service>vpls>spoke-sdp
config>service>vpls>sap>stp
This command configures the Alcatel-Lucent Spanning Tree Protocol (STP) priority for the SAP or
Description
spoke SDP.
STP priority is a configurable parameter associated with a SAP or spoke SDP. When configuration
BPDUs are received, the priority is used in some circumstances as a tie breaking mechanism to
determine whether the SAP or spoke SDP will 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 SAP or spoke SDP priority. 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.
128
Default
stp-priority — The STP priority value for the SAP . Allowed values are integer in the range of 0 to
Parameters
7210 SAS M Services Guide
Allowed values are integers in the range of 4096 — 65535 with 4096 being the
Values
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.
128
Default
Virtual Private LAN Services
For instance, if
a value of 0 is entered,
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