Alcatel-Lucent 7750 SR OS Service Manual page 409

Spoke SDP STP Operational States
The operational state of STP within a spoke SDP controls how BPDUs are transmitted and
handled when received. Defined states are:
•
•
•
•
Operationally Disabled
Operationally disabled is the normal operational state for STP on a spoke SDP in a VPLS that has
any of the following conditions:
•
•
•
If the spoke SDP enters the operationally up state with the STP administratively up and the spoke
SDP STP state is up, the spoke SDP will transition to the STP spoke SDP discarding state.
When, during normal operation, the router detects a downstream loop behind a spoke SDP,
BPDUs can be received at a very high rate. To recover from this situation, STP will transition the
spoke SDP to a disabled state for the configured forward-delay duration.
Operationally Discarding
A spoke SDP in the discarding state only receives and sends BPDUs, building the local proper
STP state for each spoke SDP while not forwarding actual user traffic. The duration of the
discarding state is explained in section
Note: in previous versions of the STP standard, the discarding state was called a blocked state.
Operationally Learning
The learning state allows population of the MAC forwarding table before entering the forwarding
state. In this state no user traffic is forwarded.
7750 SR OS Services Guide
Operationally Disabled on page 409
Operationally Discarding on page 409
Operationally Learning on page 409
Operationally Forwarding on page 410
VPLS state administratively down
Spoke SDP state administratively down
Spoke SDP state operationally down
Forward Delay on page
Virtual Private LAN Services
382.
Page 409