Virtual Private LAN Services
7750 SR OS Services Guide Page 407
Spoke SDP Path Cost
The spoke SDP 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 spoke
SDP. When BPDUs are sent out other egress 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 spoke SDPs
are controlled by complex queuing dynamics, the STP path cost is a purely static configuration.
The default value for spoke SDP path cost is 10. This parameter can be modified within a range of
1 to 200000000 (1 is the lowest cost).
CLI Syntax: config>service>vpls>spoke-sdp>stp#
path-cost stp-path-cost
Range:
1 to 200000000
Default: 10
Restore Default: no path-cost
Spoke SDP Edge Port
The spoke SDP
edge-port command is used to reduce the time it takes a spoke SDP to reach the
forwarding state when the spoke SDP is on the edge of the network, and thus has no further STP
bridge to handshake with.
The
edge-port command is used to initialize the internal OPER_EDGE variable. At any time,
when OPER_EDGE is false on a spoke SDP, the normal mechanisms are used to transition to the
forwarding state (see Forward Delay on page 382). When OPER_EDGE is true, STP assumes that
the remote end agrees to transition to the forwarding state without actually receiving a BPDU with
an agreement flag set.
The OPER_EDGE variable will dynamically be set to false if the spoke SDP receives BPDUs (the
configured edge-port value does not change). The OPER_EDGE variable will dynamically be set
to true if auto-edge is enabled and STP concludes there is no bridge behind the spoke SDP.
When STP on the spoke SDP is administratively disabled and re-enabled, the OPER_EDGE is re-
initialized to the spoke SDP configured for edge-port.
Valid values for spoke SDP edge-port are enabled and disabled with disabled being the default.
CLI Syntax: config>service>vpls>spoke-sdp>stp#
[no] edge-port
Default: no edge-port
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