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CHAPTER
5-1
Cisco ONS 15454 Installation and Operations Guide
November 2001
5
SONET Topologies
This chapter explains how to set up the Cisco ONS 15454 in different SONET topologies, including:
• Two-fiber and four-fiber bidirectional line switched rings (BLSRs)
• Unidirectional path switched rings (UPSRs)
• Subtending rings
• Linear add/drop multiplexers (ADMs)
• Path-protected mesh networks (PPMNs)
5.1 Before You Begin
To avoid errors during network configuration, Cisco recommends that you draw the complete ONS
15454 SONET topology on paper (or electronically) before you begin the physical implementation. A
sketch ensures that you have adequate slots, cards, and fibers to complete the topology.
Table 5-1 shows the SONET rings that can be created on each ONS 15454 node.
5.2 Bidirectional Line Switched Rings
The ONS 15454 can support two concurrent BLSRs in one of the following configurations:
• Two, two-fiber BLSRs, or
• One two-fiber and one four-fiber BLSR.
Each BLSR can have up to 16 ONS 15454s. Because the working and protect bandwidths must be equal,
you can create only OC-12 (two-fiber only), OC-48, or OC-192 BLSRs.
Table 5-1 ONS 15454 Rings
Ring Type Maximum per node
All rings 5
BLSRs 2
2-Fiber BLSR 2
4-Fiber BLSR 1
UPSR 4