Alcatel-Lucent 7750 SR Manual page 670

Virtual Private LAN Services
system and has a reference space much bigger than the 12 bits definable in a configuration BPDU.
STP takes the internal representation value of a SAP and identifies it with it's own virtual port number
that is unique to every other SAP defined on the TLS. The virtual port number is assigned at the time
that the SAP is added to the TLS. Since the order that the SAP was added to the TLS is not preserved
between reboots of the system, the virtual port number may change between restarts of the STP
instance.
The virtual port number cannot be administratively modifed.
priority
Syntax priority bridge-priority
no priority
Context config>service>vpls>stp
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 or
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
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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.
7750 SR OS Services Guide