Virtual Private LAN Service
294
FD 100/320Gbps NT and FX NT IHub Services Guide
3HH-11985-AAAA-TQZZA Issue: 13
5.16.3.22 priority
Table 204 priority command
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.
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.
Item Description
(2 of 2)
Item Description
Syntax priority stp-priority
no priority
Context configure>service>vpls>sap>stp
Description This command configures the Nokia Spanning Tree Protocol (STP) priority for the SAP.
STP priority is a configurable parameter associated with an SAP. When configuration BPDUs
are received, the priority is used in some circumstances as a tie breaking mechanism to
determine whether the SAP 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 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 an 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 SAP priority parameter. For instance, if a value
of 0 is entered, 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 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.
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