Post on 06-Jan-2016
description
Tx Rx
W
P
Splitter Switch
(Working Fiber)
(Protection Fiber)
Traffic flow
Traffic flow
Linear Protection - 1+1 APS
•Fast protection;
•Switching is initiated and executed by the receiver without its knowing the actual status of the transmitter. Thus, no communication between receiver and transmitter takes place (no signaling required between end-points)
•High cost (duplication of WDM line system)
•Both 1+1 and 1:1 techniques protect against only a fiber cut. In case of node failure, the traffic is lost.
Point-to-Point Link Protection
Tx Rx
W
P
Switch
Traffic flow
Switch
Linear Protection - 1:1 APS
•Fast protection (but slower than 1+1)
•Switching is initiated by the receiver but has to be done by the transmitter. Thus, communication between receiver and transmitter is required (signaling required between end-points).
•The Signaling is effected through an automatic protection switching (APS) signaling channel and an APS protocol.
•High cost (duplication of line system) BUT: possibility for low priority preemptible traffic
• Physically, an APS signaling channel can be established by using an out of band wavelength (e. g., 1510 nm signal)
Tx Rx
W
P
Splitter SwitchTraffic flow
Linear Protection – 1:NAPS
Tx Rx
W
P
Traffic flow
Tx Rx
W
P
Traffic flow
P
APS ChannelLow-priority traffic Low-priority traffic
Bi-directional Line Switched RingSpan Switch
S
F
CB
S
S
S
S
P
P
P
P
P
D
E
S
P
X
A
Original Circuit
Protection Switch
Bi-directional Line Switched RingRing Switch
S
E
CB
A
F
S
S
S
S
P
P
P
P
P
D
S
P
Original Circuit
Ring Switch
X
Bi-directional Line Switched RingRing Switch - Node Failure
F
CB
A
S
S
S
S
S
P
P
P
P
P
D
S
P
E xOriginal Circuit
Ring Switch