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Chapter 12
SONET Topologies and Upgrades
Table 12-1
Ring Type
Path protection with LDCC and SDCC 26
1. Total SDCC usage must be equal to or less than 84 SDCCs.
2. See the
3. Total LDCC usage must be equal to or less than 28 LDCCs.
4. See the
5. Total LDCC and SDCC usage must be equal to or less than 84. When LDCC is provisioned, an
12.2 Bidirectional Line Switched Rings
The ONS 15454 can support five concurrent bidirectional line switch rings (BLSRs) in one of the
following configurations:
•
•
Each BLSR can have up to 32 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.
For best performance, BLSRs should have one LAN connection for every ten nodes in the BLSR.
Note
12.2.1 Two-Fiber BLSRs
In two-fiber BLSRs, each fiber is divided into working and protect bandwidths. For example, in an
OC-48 BLSR
protection. Working traffic (STSs 1 to 24) travels in one direction on one fiber and in the opposite
direction on the second fiber. The Cisco Transport Controller (CTC) circuit routing routines calculate
the shortest path for circuits based on many factors, including user requirements, traffic patterns, and
distance. For example, in
unless that fiber is full, in which case circuits are routed on Fiber 2 through Node 3 and Node 2. Traffic
from Node 0 to Node 2 (or Node 1 to Node 3) can be routed on either fiber, depending on circuit
provisioning requirements and traffic loads.
78-18106-01
ONS 15454 Rings with Redundant TCC2/TCC2P Cards (continued)
"12.3 Path Protection" section on page
"12.3 Path Protection" section on page
SDCC termination is allowed on the same port, but is not recommended. Using SDCC and LDCC on
the same port is only needed during a software upgrade if the other end of the link does not support
LDCC. You can provision SDCCs and LDCCs on different ports in the same node.
Five two-fiber BLSRs
Four two-fiber and one four-fiber BLSR
(Figure
12-1), STSs 1 to 24 carry the working traffic, and STSs 25 to 48 are reserved for
Figure
Maximum Rings per Node
5
12-14.
12-14.
12-1, circuits going from Node 0 to Node 1 typically travel on Fiber 1,
Cisco ONS 15454 Reference Manual, R8.5
12.2 Bidirectional Line Switched Rings
12-3
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