Cisco Cisco ONS 15454 SONET Multiservice Provisioning Platform (MSPP) Guía De Diseño

OL-4556-01

 

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Each 4-Fiber BLSR can have up to 32 ONS 15454 nodes. Because the working and protect 
bandwidths must be equal, you can create only OC-48, or OC-192 BLSRs.  Table 2-25 shows the 
bi-directional bandwidth capacities of 4-Fiber BLSRs. 
 

 

OC-N Rate 

Working Bandwidth 

Protection Bandwidth 

Ring Capacity 

OC-48 

STS 1-48 (Fiber 1) 

STS 1-48 (Fiber 2) 

48 x N

1

 – PT

2 

OC-192 

STS 1-192 (Fiber 1) 

STS 1-192 (Fiber 2) 

192 x N – PT  

1

 N equals the number of ONS 15454 nodes configured as BLSR nodes. 

2

 PT equals the number of STS-1 circuits passed through ONS 15454 nodes in the ring (capacity 

can vary depending on the traffic pattern). 

 

 

 

 
4-Fiber Span and Ring Switching 
 
Cisco ONS 15454 4-Fiber BLSRs provide span and ring switching as follows: 
 

    Span switching, shown in Figure 2-48, occurs when a working span fails.  Traffic switches 

to the protect fibers in less than 50 ms between Node 0 and Node 1 and then returns to 
the working fibers.  Multiple span switches can occur at the same time.  Multiple span 
switches can be present on a 4-Fiber BLSR and not cause traffic to drop. 

 

    Ring switching, shown in Figure 2-49, occurs when a span switch cannot recover traffic, 

such as when both the working and protect fibers fail on the same span.  In a ring switch, 
traffic is routed within 50 ms to the protect fibers throughout the full ring. 

 
The K1 byte of the Line Overhead carries the bridge request and associated priorities.  These 
priorities are used to determine if a bridge request can be fulfilled, when an existing ring or span 
switch is present on the 4-Fiber BLSR.  Within the K1 byte, bits 1 through 4 define the “request