Setting Up Tunable Dispersion Compensating Units

This chapter explains the Tunable Dispersion Compensating Units (T-DCU) used in Cisco ONS 15454 dense wavelength division multiplexing (DWDM) networks.

For card safety and compliance information, refer to the Regulatory Compliance and Safety Information for Cisco ONS Platforms document.


Note

Unless otherwise specified, “ONS 15454” refers to both ANSI and ETSI shelf assemblies.

The T-DCU unit compensates for chromatic dispersion (CD) of the transmission fiber. The T-DCU provides two line cards with varied set of tunable wavelengths to compensate for CD.

The T-DCU card provides a selectable set of discrete negative chromatic dispersion values to compensate for chromatic dispersion of the transmission line. The card operates over the entire C-band (in the range of 1529.0 nm to 1562.5 nm) and monitors the optical power at the input and the output ports. The two types of T-DCU line cards are:

  • TDC-CC (Coarse T-DCU)

  • TDC-FC (Fine T-DCU)


Note

Each T-DCU card is marked with a symbol that corresponds to a slot (or slots) on the ONS 15454 shelf assembly. Cards should be installed in slots that have the same symbols. See the “Card Slot Requirements” section in the Cisco ONS 15454 Hardware Installation Guide.

Safety Labels

For information about safety labels, see the “G.1.2  Class 1M Laser Product Cards” section on page G-4.

TDC-CC and TDC-FC Cards

The TDC-CC card provides 16 values of CD ranging from 0 to -1650 ps/nm with a granularity of 110 ps/nm in the C-band spectrum.

The TDC-FC card provides 16 values of CD ranging from 0 to -675 ps/nm with a granularity of 45 ps/nm in the C-band spectrum.

You can configure the TDC-CC and TDC-FC cards for the CD value listed in the following table.

Table 1. TDC-CC and TDC-FC Tunable CD Value

Unit Configuration

TDC-CC [ps/nm]

TDC-FC [ps/nm]

0

0

0

1

-110

-45

2

-220

-90

3

-330

-135

4

-440

-180

5

-550

-225

6

-660

-270

7

-770

-315

8

-880

-360

9

-990

-405

10

-1100

-450

11

-1210

-495

12

-1320

-540

13

-1430

-585

14

-1540

-630

15

-1650

-675

Note

The default TDC-CC CD value for Coarse Unit is 0. The default TDC-FC value for Fine Unit is 0.

Key Features

The TDC-CC and TDC-FC cards provide these features:

  • Single slot card with three LEDs on the front panel.

  • Two LC-PC-II optical connectors on the front panel.

  • Operates in slots from slot 1 to 6 and 12 to 17.

  • Operates over the C-band (wavelengths from 1529 nm to 1562.5 nm) of the optical spectrum.

  • Allows upto 16 provisionable CD values for chromatic dispersion compensation.

  • Connects to OPT-PRE, OPT-AMP-C, OPT-RAMP-C, and OPT-RAMP-CE amplifiers and 40-SMR-1 and 40-SMR-2 cards.

  • Supports performance monitoring and alarm handling for selectable thresholds.

  • Allows monitoring and provisioning using CTC, SNMP, or TL1.

For more information about the TDC-CC and TDC-FC cards, see http://www.cisco.com/en/US/prod/collateral/optical/ps5724/ps2006/data_sheet_c78-581114.html

Optical Ports

The T-DCU unit contains the DC-RX (input) and DC-TX (output) ports. The optical signal enters the DC-RX port, compensates the chromatic dispersion and then exits from the DC-TX port.

TDC-CC and TDC-FC Card Functions

The functions of the TDC-CC and TDC-FC cards are:

  • G.15  Lamp Test, page G-22

  • Card level indicators— Table G-1 on page G-8

Optical Performance

The TDC-CC and TDC-FC cards monitor the optical input power and optical output power of the fiber. It monitors the insertion loss from the input (DC-RX) to the output (DC-TX) port, with the help of the two photodiodes PD1 and PD2. The TDC-CC and TDC-FC cards report the minimum, average, and maximum power statistics of each of the monitored ports or channels in the specific card. To view the optical power statistics of the TDC-CC and TDC-FC cards, refer to the Monitor Performance document. The performance data is recorded at 15 minutes and 24 hours intervals.


Note

You can view the performance monitoring (PM) data of the card using CTC, SNMP, and TL1 interfaces.

Note

The PM data is stored on a wrap-around basis at 32 x 15 min. and 2 x 24 hour intervals.