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Cisco Ons 15501 Applications; Point-To-Point Topologies; Ring Topologies - Cisco ONS 15501 User Manual

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Chapter 1
Product Overview

Cisco ONS 15501 Applications

The Cisco ONS 15501 supports the following applications:

Point-to-Point Topologies

In a metropolitan point-to-point DWDM network, the Cisco ONS 15501 can function as a pre-, post-,
and/or inline amplifier. Most metropolitan point-to-point DWDM networks require post-amplifiers, but
if a given span length exceeds the unit gain (>17 dB), a preamplifier may also be required to handle the
optical link loss budget. When the span length greatly exceeds 17 dB, an inline amplifier might also be
Because of the wide input power range (-29 to 0 dBm) of the Cisco ONS 15501, trunk attenuation is
typically also necessary, especially when the unit is used as a post-amplifier. For instance, when the per
channel output power from the node is -5 dBm in a 32-channel system, the total output power from the
node is +10 dBm. Thus, at least 10 dB of trunk attenuation is required directly preceding the amplifier.
The Cisco ONS 15501 can also be tuned to meet post- or inline amplification input power requirements.
Assuming that the typical per channel power levels in a point-to-point network are identical at the source
node, and that there are fewer than four amplifiers between source and destination nodes, it is not
necessary to maintain per channel power equalization to satisfy each amplifier's total input power
requirement and maintain acceptable OSNR for each channel.

Ring Topologies

An amplified ring topology requires more fine-tuning of power for each channel or band.
illustrates a hubbed ring network utilizing counter-clockwise signal transmission. All bands (A, B, C and
D) are transmitted from node 1. Node 2 terminates and transmits bands A and B; node 3 terminates and
transmits band C; and node 4 terminates and transmits band D.
78-14134-01, Release 1.0
Point-to-point topologies
Ring topologies
Adding or dropping wavelengths
Adjusting to span loss changes
Cisco ONS 15501 Applications
Figure 1-1
Cisco ONS 15501 User Guide



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