Nokia 7302 Manual page 206

Virtual Private LAN Service
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configure>service>vpls>sap>stp# [no] shutdown
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SAP Virtual Port Number
The virtual port number uniquely identifies an SAP within configuration BPDUs. The
internal representation of an 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 an SAP and identifies it with it's own virtual port
number that is unique to every other SAP defined on the VPLS. The virtual port
number is assigned at the time that the SAP is added to the VPLS.
Since the order in which SAPs are added to the VPLS is not preserved between
reboots of the system, the virtual port number may change between restarts of the
STP instance. To achieve consistency after a reboot, the virtual port number can be
specified explicitly.
configure>service>vpls>sap>stp# port-num number
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SAP Priority
SAP priority allows a configurable "tie breaking" parameter to be associated with an
SAP. When configuration BPDUs are being received, the configured SAP priority will
be used in some circumstances to determine whether an SAP will be designated or
blocked. These are the values used for CIST when running MSTP.
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 SAP priority by taking the configured priority value and
masking out the lower four bits. The result is the value that is stored in the SAP
priority parameter. For example, if a value of 0 was entered, masking out the lower
4 bits would result in a parameter value of 0. If a value of 255 was entered, the result
would be 240.
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SAP Admin Down
An administratively down state allows a service provider to prevent an SAP from
becoming operationally blocked. BPDUs will not originate out the SAP towards
the customer.
The administratively down state allows a loop to form
Note —
within the VPLS.
Range: shutdown or no shutdown
Default: no shutdown (SAP admin up)
Range: 1 — 2047
Default: (automatically generated)
Restore Default: no port-num
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FD 100/320Gbps NT and FX NT IHub Services Guide
Issue: 13