FD 100/320Gbps NT and FX NT IHub Services Guide Virtual Private LAN Service
Issue: 13 3HH-11985-AAAA-TQZZA 207
The default value for SAP priority is 128. This parameter can be modified within a
range of 0 to 255, 0 being the highest priority. Masking causes the values actually
stored and displayed to be 0 to 240, in increments of 16.
configure>service>vpls>sap>stp# priority stp-priority
• Range: 0 to 255 (240 largest value, in increments of 16)
• Default: 128
• Restore Default: no priority
SAP Path Cost
The SAP 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, the newly
calculated root path cost is used. These are the values used for CIST when running
MSTP.
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 ISAM the STP path cost
is a purely static configuration.
The default value for sap-path-cost is 10. This parameter can be modified within a
range of 1 to 65535, 1 being the lowest cost.
configure>service>vpls>sap>stp# path-cost sap-path-cost
• Range: 1 to 200000000
• Default: 10
• Restore Default: no path-cost
SAP Link Type
The SAP link-type parameter instructs STP on the maximum number of bridges
behind this SAP. If there is only a single bridge, transitioning to forwarding state will
be based on handshaking (fast transitions). If more than two bridges are connected
via a shared media, their SAPs should all be configured as shared, and timer-based
transitions are used.
Valid values for SAP link-type are shared and pt-pt with pt-pt being the default.
configure>service>vpls>sap>stp# link-type {pt-pt|shared}
Default: link-type pt-pt
Restore Default: no link-type
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