Cisco Systems Cisco ONS 15310-MA, ONS 15310-CL, ONS 15310-MA RPR Framing Process

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Cisco ONS 15310-CL, ONS 15310-MA, and ONS 15310-MA SDH Ethernet Card Software Feature and Configuration Guide, R9.1 and R9.2
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Chapter 15 Configuring Resilient Packet Ring on the ML-Series Card
Understanding RPR
Figure 15-2 RPR Ring Wrapping
In case of a ring failure, the ML-Series cards connected to the failed section of the RPR detect the failure
through the SONET path alarms. When any ML-Series card receives this path-AIS signal, it wraps the
POS interface that received the signal.
Note If the POS interfaces on the ML100T-8 cards on either 15310MA or 15310CL receives the
SF-P condition, then the SPR ring does not wrap.
Note If the carrier delay time is changed from the default, the new carrier delay time must b e configured on
all the ML-Series card interfaces.
Note ML-Series card POS interfaces normally send an alarm for signal label mismatch failure in the STS path
overhead (PDI-P) to the far end when the POS link goes down or when RPR wraps. ML-Series card POS
interfaces do not send PDI-P to the far-end when PDI-P is detected, when a remote defection indication
alarm (RDI-P) is being sent to the far end, or when the only defects detected are generic framing
procedure (GFP)-loss of frame delineation (LFD), GFP client signal fail (CSF), virtual concatenation
(VCAT)-loss of multiframe (LOM), or VCAT-loss of sequence (SQM).
RPR Framing Process
The ML-Series card uses a proprietary RPR frame and HDLC or GFP-F framing. It attaches the RPR
frame header to each Ethernet frame and encapsulates the RPR frame into the SONET payload for
transport over the SONET topology. The RPR header is removed at the egress ML-Series card.
Figure 15-3 illustrates the RPR frame.
Fiber Cut
ML-Series RPR
Ring Wrap
Ring Wrap
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