Cisco Systems manual Cisco ONS 15501 Front Panel, Adding or Dropping Wavelengths

Chapter 1 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 the ring, some of the channels in the ring will not meet 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 equalized 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 OSNR.

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 trunk line, between the OADM and the EDFA, is also an effective method. The Cisco ONS 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 Cisco ONS 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 equalization.

Cisco ONS 15501 Front Panel

Figure 1-2shows the Cisco ONS 15501 front panel. The front panel provides an all-front access interface (fibers, power, alarm contact, and management) that complies with international standards. Table 1-4explains the front panel features.

Figure 1-2 Cisco ONS 15501 Front Panel
	3		5		7			10
					RS-232
			POWER
			FAIL				-48V RET	-48V RET
			LOS
INVISIBLE LASER RADIATION.
DO NOT VIEW DIRECTLY WITH
OPTICAL INSTRUMENTS.
CLASS 1M LASER PRODUCT.				Cisco ONS 15501	ALARM OUT	LAN
1	2	4	6		8	9	11	11

DC connectors shown with cover removed

68377

	Cisco ONS 15501 User Guide
78-14134-02, Release 2.0		1-7