The Cisco ONS 15216 EDFA1 provides bandwidth-on-demand to extend DWDM links by hundreds of kilometers. This manual describes how to install and operate the ONS 15216 EDFA1, which is a DWDM-enabling technology for multiservice ring DWDM networks. The ONS 15216 EDFA1 is part of the Cisco ONS 15216 metro regional DWDM product line that includes red and blue terminal filters, a one-channel and two-channel optical add/drop multiplexer (OADM), and an optical performance manager (OPM).The ONS 15216 EDFA1 is a C-band EDFA that has constant gain control, gain-flatness, transient suppression, and low-noise figure optimized for metro DWDM applications. These features enable the ONS 15216 EDFA1 to add/drop optical signals from a span in a DWDM network without degrading of the other optical signals in the same span.The ONS 15216 EDFA1 uses gain-control technology, which is the ability to keep the amplification per wavelength constant at all times as wavelengths are added/dropped from an optical fiber. Every wavelength in an ONS 15216 EDFA1, regardless of number, is guaranteed to be amplified by 23 dB. Any number of wavelengths can be amplified, as long as the total input power of all wavelengths is between -29 dBm and -6 dBm. Unlike previous generations of EDFAs, the ONS 15216 reconfigures itself rapidly to ensure constant gain and gain flatness.