Master-Slave Operation
Page 140 7210 SAS-X, R6 OS Services Guide
transitioning a spoke SDP from standby to active receiving and/or processing a pseudowire
preferential forwarding status message before those transitioning a spoke SDP to standby. This
transient condition is most likely when a forced switch-over is performed, or the relative
preferences of the spoke SDPs is changed, or the active spoke SDP is shutdown at the master
endpoint. During this period, loops of unknown traffic may be observed. Fail-overs due to
common network faults that can occur during normal operation, a failure of connectivity on the
path of the spoke SDP or the SAP, would not result in such loops in the data path.
Local Rules at Slave VLL PE
It must not be possible to configure standby-signaling-slave on endpoints or spoke SDPs bound to
an IES, VPRN, ICB, MC-EP or that form part of an MC-LAG or MC-APS.
If ‘standby-signaling-slave’ is configured on a given spoke SDP or explicit endpoint, then the
following rules apply. Note that the rules describe the case of several spoke SDPs in an explicit
endpoint. The same rules apply to the case of a single spoke SDP outside of an endpoint where no
endpoint exists:
Rules for processing endpoint SAP active/standby status bits:
→ Since the SAP in endpoint X is never a part of a MC-LAG/MC-APS instance, a
forwarding status of ACTIVE is always advertised.
Rules for processing and merging local and received endpoint object status Up/Down operational
status:
1. Endpoint ‘X’ is operationally UP if at least one of its objects is operationally UP. It is Down
if all its objects are operationally down.
2. If all objects in endpoint ‘X’ transition locally to Down state, and/or received a “SAP Down”
notification via remote T-LDP status bits or via SAP specific OAM signal, and/or received
status bits of “SDP-binding down”, and/or received status bits of “PW not forwarding”, the
node must send status bits of “SAP Down” over all ‘Y’ endpoint spoke SDPs.
3. Endpoint ‘Y’ is operationally UP if at least one of its objects is operationally UP. It is Down
if all its objects are operationally down.
4. If a spoke SDP in endpoint ‘Y’, including the ICB spoke SDP, transitions locally to Down
state, the node must send T-LDP “SDP-binding down” status bits on this spoke SDP.
5. If a spoke SDP in endpoint ‘Y’, received T-LDP “SAP down” status bits, and/or received T-
LDP “SDP-binding down” status bits, and/or received status bits of “PW not forwarding”,
the node saves this status and takes no further action. The saved status is used for selecting
the active transmit endpoint object as per the pseudo-code in Section 5.1.2.
6. If, all objects in endpoint ‘Y’, or a single spoke SDP that exists outside of an endpoint (and
no endpoint exists), transition locally to down state, and/or received T-LDP “SAP Down”
status bits, and/or received T-LDP “SDP-binding down” status bits, and/or received status
bits of “PW not forwarding”, and/or the received status bits of ‘PW FWD standby’, the node
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