Alcatel-Lucent 7210 SAS M Service Manual page 406

Virtual Private LAN Services
The path cost is used by STP to calculate the path cost to the root bridge. The path cost in BPDUs
received on the root port is incremented with the configured path cost for that SAP. When BPDUs are
sent out other egress SAPs or spoke SDPs, the newly calculated root path cost is used.
STP suggests that the path cost is defined as a function of the link bandwidth. Since SAPs are
controlled by complex queuing dynamics, in the 7210 SAS the STP path cost is a purely static
configuration.
The no form of this command returns the path cost to the default value.
path-cost — The path cost for the SAP or spoke SDP.
port-num
Syntax [no] port-num virtual-port-number
Context config>service>vpls>sap>stp
config>service>vpls>spoke-sdp>stp
This command configures the virtual port number which uniquely identifies a SAP within
Description
configuration bridge protocol data units (BPDUs). The internal representation of a SAP is unique to a
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
config>template>vpls-template>stp
The bridge-priority command is used to populate the priority portion of the bridge ID field within
Description
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.
By default, the bridge priority is configured to 4096 which is the highest priority.
Default
bridge-priority — The bridge priority for the STP instance.
Parameters
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1 — 200000000 (1 is the lowest cost)
Values
10
Default
7210 SAS M Services Guide