R3102-R3103-HP 6600/HSR6600 Routers High Availability Configuration Guide

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Figure 14 Schematic diagram before and after protection switchover
As shown in Figure 14, traffic travels from station D to station B along Ringlet 0. The transmission path
is station D—station E—station A—station B. After the span between station A and station E fails, a
protection switchover occurs.
 In wrapping mode, traffic that should originally travel from station E to A along Ringlet 0 is
directed to Ringlet 1 to reach station A. The new transmission path is station D—station
E—station D—station C—station B—station A—station B.
 In steering mode, traffic that should have traveled from station D to station B along Ringlet 0 is
steered to Ringlet 1 for transmission. The new transmission path is Station D—Station C—Station
B.
RPR protection switching uses the following protection hierarchy listed in the order of decreasing
severity:
 Forced switch (FS)
 Signal fail (SF), related to current physical status.
 Signal degrade (SD), related to current physical status.
 Manual switch (MS)
 Wait to restore (WTR)
 Idle
Ringlet 1
Ringlet 0
Station D
Station B
Data transmission path
Station C
Station E
Station A
Station A
Station E
Station B
Station C
Station D Station D
Station B
Station C
Station E
Station A
Data transmission after protection switchover
(wrapping mode)
Data transmission before
protection switchover
Data transmission after protection switchover
(steering mode)
Link failure