Protection Switching Modes; Path Switching Modes; Protocols And Standards - HP MSR2000 Configuration Manual

Protection switching modes

MPLS PS supports the following protection switching modes:
1:1 protection switching—Typically, traffic travels along the working tunnel. When either of the
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following occurs, the ingress node selects the traffic forwarding tunnel (working or protection tunnel)
according to the protection state:
The ingress or egress node detects a failure on the working tunnel.
An external switching command is executed on the node.
1+1 protection switching—Typically, traffic travels along both the working and protection tunnels,
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and the egress node receives traffic from the working tunnel. When either of the following occurs,
the egress node determines from which tunnel it receives traffic according to the protection state:
The ingress or egress node detects a failure on the working tunnel.
An external switching command is executed on the node.
NOTE:
The tunnel ingress or egress node can detect tunnel failures through MPLS BFD or other detection
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mechanisms. For more information about MPLS BFD, see "Configuring MPLS OAM."
The protection state indicates the comprehensive status of a PS protection group, For more information,
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see the display mpls forwarding protection command in

Path switching modes

A bidirectional MPLS TE tunnel switches the traffic forwarding path in one of the following modes:
Unidirectional path switching—When an external switching command or a signal fail triggers
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protection switching for traffic in one direction:
PS switches the traffic forwarding tunnel only in this direction.
The traffic forwarding tunnel in the other direction does not change.
Bidirectional path switching—When an external switching command or a signal fail triggers
•
protection switching for traffic in one direction, PS switches the traffic forwarding tunnels in both
directions.
The ingress node and the egress node periodically send Protection State Coordination (PSC)
packets to each other to coordinate the protection state. When one tunnel end performs a PS, the
other end also performs a PS.
1:1 protection switching supports both unidirectional and bidirectional path switching. 1+1 protection
switching supports only bidirectional path switching.

Protocols and standards

• RFC 6372, MPLS Transport Profile (MPLS-TP) Survivability Framework
RFC 6378, MPLS Transport Profile (MPLS-TP) Linear Protection
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MPLS Command Reference
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.