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Cisco ONS 15501 User Guide
78-14134-02, Release 2.0
Chapter1 Product Overview
Cisco ONS 15501 Front Panel
of the add bands. This significantly degrades the OSNR of the pass-through bands, and in cases where
there are more than two EDFAs in th e ring, some of the channels in the ring will not mee t OSNR
requirements.
To solve this problem, optical power attenuation should be applied on a per channel or per band basis.
More attenuation is typically required for the add bands than for the pass-through bands. At the EDFA
input, the individual channel or band power levels should be equaliz ed as close as possible to the
maximum per channel input power level, (for example, -15 dBm in a 32-channel system). This process
of optical power equalization is necessary to obtain better OS NR.
Inserting attenuation devices such as VOAs (variable optical attenuators) between the OADM (optical
add/drop multiplexer) and the transmitter allows optical power management of individual channels. Per
band power management at the tru nk line, between the OADM and the EDFA, is also an effective
method. The CiscoONS 15501 is capable of supporting either approach, and its wide input range (-29
to 0 dBm) makes it an ideal amplifier for a broad array of ring network designs.

Adding or Dropping Wavelengths

Automatic gain control reacts to the adding or dropping of wavelengths in a network, without requiring
power equalization tuning. The fast response of the CiscoONS 15501 reduces the impact of adding or
dropping channels, and prevents BER hits.

Adjusting to Span Loss Changes

It is typically necessary to adjust gain and attenuation values both for trunk attenuation and channel or
band power equalizat ion.
Cisco ONS 15501 Front Panel
Figure1-2 shows the Cisco ONS 15501 front panel. The front panel provides an all-front access
interface (fibers, power, alarm conta ct, and management) that complies with internationa l standards.
Table 1 -4 explains the front panel features.
Figure1-2 Cisco ONS 15501 Front Panel
POWER
ALARM OUT
Cisco ONS 15501
FAIL
LOS
-48V RET -48VRET
LAN
RS-232
DC connectors shown
with cover removed

53 7 10

1 8 9 11 112 6

68377

4

INVISIBLE LASER RADIATION.
DO NOT VIEW DIRECTLY WITH
OPTICAL INSTRUMENTS.
CLASS 1M LASER PRODUCT.