Author: Fiber-MART.COM

In traditional optical fiber networks, information is transmitted through optical fiber by a single lightbeam. In a wavelength division multiplexing (WDM) network, the vast optical bandwidth of a fiber is carved up into wavelength channels, each of which carries a data stream individually. The multiple channels of information (each having a different carrier wavelength) are transmitted simultaneously over a single fiber. The reason why this can be done is that optical beams with different wavelengths propagate without interfering with one another. When the number of wavelength channels is above 20 in a WDM system, it is generally referred to as Dense WDM or DWDM.

What Is DWDM

DWDM, short for dense wavelength division multiplexing, is an optical technology used to increase bandwidth over existing fiber optic backbones. DWDM works by combining and transmitting multiple signals simultaneously at different wavelengths on the same fiber. It increases the capacity of embedded fiber by assigning incoming optical signals to specific frequencies (wavelengths) with a designated frequency band and then multiplexing the resulting signals out onto one fiber. In effect, one fiber is transformed into multiple virtual fibers. So, if you were to multiplex eight OC-48 signals into one fiber, you would increase the carrying capacity of that fiber from 2.5 Gb/s to 20 Gb/s. DWDM has the ability to transport up to 80 wavelengths in what is known as the Conventional band or C band spectrum, with all 80 channels in the 1550nm region. A key advantage of DWDM is that it’s protocol- and bit-rate-independent. DWDM-based networks can transmit data in IP, ATM, SONET/SDH, and Ethernet.

Advantages of DWDM

DWDM is designed for long-haul transmission where wavelengths are packed tightly together, providing a high-capacity solution in telecom networks. In DWDM system, far more channels are possible within the same fiber and dispersion compensation can be applied. Besides, it stays completely within the C-band where attenuation and dispersion are far lower than other bands. Moreover, DWDM takes advantage of the operating window of the Erbium Doped Fiber Amplifier (EDFA) to amplify the optical channels and extend the operating range of the system to over 1500 kilometers. The use of DWDM technology has proven to be the optimal way of combining cost efficient transport with advanced functionality, which can cope with the bandwidth explosion from the access network.

DWDM Equipment

DWDM is a core technology in an optical transport network. The essential components of DWDM (DWDM Equipment) are shown in the following picture. The first one is transmitter (transmit transponder) which changes electrical bits to optical pulses. It is frequency specific and uses a narrow-band laser to generate the optical pulse. The second one is the multiplexer or demultiplexer which combines and separates discrete wavelengths respectively. The link is optical fiber that exhibits low loss and transmission performance in the relevant wavelength spectra, as well as the flat-gain optical amplifiers to boost the signal on longer spans. On the end is the receiver (receive transponder) which changes optical pulses back to electrical bits and uses wideband laser to provide the optical pulse.

fiber-mart.com provides a vast range of DWDM products to help build and expand fiber optic networks. For example, we offer DWDM MUX DEMUX modules with 50GHz/100GHz/200GHz channel spacing, DWDM OADM modules with various configurations and DWDM transceivers which can support 155Mbps to 10Gbps data transmissions.

Introduction to Optical Transponder

Optical transponder is also referred to as WDM transponder, wavelength-converting transponder or OEO (Optical-Electrical-Optical) 3R (re-timing, re-shaping, and re-amplifying) converter, and the word “transponder” is named according to the combination between transmitter and responder. It is an important unit in WDM system which main function is to convert the wavelength and the pattern of the optical signals and amplify the optical signals for long-haul transmission. At present, the optical transponder unit is commonly used in 10G connections including SFP+ to XFP, SFP+ to SFP+ and XFP to XFP fiber connections, and 40G QSFP+ to QSFP+ connections.

Working Principle of Optical Transponder

The optical transponder is designed to automatically receive a signal, amplify it and then retransmit the signal with another wavelength, without changing the content of the signal, which enables the different system to be connected. For instance, a 10G DWDM system can be deployed on the basis of a normal 10G system if using the optical transponder to convert a 850nm signal into a 1550nm one. What’s the working principle of the optical transponder? In general, when an optical input signal passes through the optical transponder, it will be firstly converted into an electrical one. Then a logical copy of the input signal is generated that features a new amplitude and shape and is used for driving the transmitter. Finally, an optical output signal with a new wavelength would be generated, as shown in the following figure.

Wavelength Conversion Case Analysis

As mentioned above, the optical transponder unit plays an important role in WDM system, which is very welcomed when deploying a CWDM or DWDM system on the basis of a normal system. It is well known that 850nm, 1310nm or 1550nm are used in a normal system for optical signal transmission, while CWDM or DWDM wavelengths are applied in a CWDM or DWDM system. Hence, if we want to transmit the normal signals to a CWDM or DWDM system, the optical transponder should be required that enables the normal wavelengths to be converted into CWDM or DWDM ones without changing the signal data. Here shows a wavelength conversion case by using the optical transponder.

We can learn from the case that a 10G-LR 1310nm SFP+ module is connected to a 10G switch on site A, while a 10G CWDM SFP+ module working on 1610nm is used with the CWDM Mux Demux on site B. As the 10G 1310nm signal from site A is required to be transmitted to the existing CWDM system on site B, a two SFP+ ports optical transponder should be used for converting the 10G 1310nm signal into a 10G 1610nm CWDM signal. To achieve this, another 10G-LR 1310nm SFP+ module and 10G CWDM 1610nm SFP+ module should be inserted into the 10G SFP+ to SFP+ optical transponder, separately. Furthermore, fiber patch cables are required to link the two 10G-LR 1310nm SFP+ modules and two 10G CWDM 1610nm SFP+ modules together, so that a complete link for wavelength conversion can be done.

Conclusion

The optical transponder is an important component in WDM system that makes the wavelength conversion easy, so that the signal data can be transmitted from a normal system to a WDM system. For instance, with the use of the optical transponder unit, a 1310 signal from a 10G fiber optical network can be converted into a 1610 CWDM signal and transmitted to the 10G CWDM network. If you are facing the problem about wavelength conversion for connection between a normal network with a WDM network as noted above, the optical transponder is quite recommendable for you.

1. WHAT IS FIBER OPTIC TRANSPONDER?

In optical fiber communications, a transponder is the element that sends and receives the optical signal from a fiber. A transponder is typically characterized by its data rate and the maximum distance the signal can travel.

>> The difference between a fiber optic transponder and transceiver

A transponder and transceiver are both functionally similar devices that convert a full-duplex electrical signal in a full-duplex optical signal. The difference between the two being that transceivers interface electrically with the host system using a serial interface, whereas transponders use a parallel interface to do so.

So transponders provide easier to handle lower-rate parallel signals, but are bulkier and consume more power than transceivers.

>> Major functions of a fiber optic transponder includes:

Electrical and optical signals conversions

Serialization and deserialization

Control and monitoring

2. APPLICATIONS OF FIBER OPTIC TRANSPONDER

Multi-rate, bidirectional fiber transponders convert short-reach 10 Gb/s and 40 Gb/s optical signals to long-reach, single-mode dense wavelength division multiplexing (DWDM) optical interfaces.

The modules can be used to enable DWDM applications such as fiber relief, wavelength services, and Metro optical DWDM access overlay on existing optical infrastructure.

Supporting dense wavelength multiplexing schemes, fiber optic transponders can expand the useable bandwidth of a single optical fiber to over 300 Gb/s.

Transponders also provide a standard line interface for multiple protocols through replaceable 10G small form-factor pluggable (XFP) client-side optics.

The data rates and typical protocols transported include synchronous optical network/synchronous digital hierarchy (SONET/SDH) (OC-192 SR1), Gigabit Ethernet (10GBaseS and 10GBaseL), 10 G Fibre Channel (10 GFC) and SONET G.709 forward error correction (FEC)(10.709 Gb/s).

Fiber optic transponder modules can also support 3R operation (reshape, retime, regenerate) at supported rates.

Often, fiber optic transponders are used to for testing interoperability and compatibility. Typical tests and measurements include jitter performance, receiver sensitivity as a function of bit error rate (BER), and transmission performance based on path penalty.Some fiber optic transponders are also used to perform transmitter eye measurements.

>> Major Applications of fiber optic transponder

300-pin MSA fiber optic transponders can transparently carry a native 10G LAN PHY, SONET/SDH and Fibre Channel payload with a carrier grade DWDM Optical Transport Network (OTN) interface without the need for bandwidth limitation.

Transponders offer G.709 compliant Digital Wrapper, Enhanced Forward Error Correction (FEC) and Electrical Dispersion Compensation (EDC) for advanced optical performance and management functions superior to those found in DWDM Transponder systems.

They support full C or L band tunability and is designed to interoperate with any Open DWDM line system that support 50GHz spaced wavelengths per the ITU-T grid.

Enables reach extension on SONET, Storage Area Network (SAN), Gigabit Ethernet, and dispersion limited links

Wavelength services and Metro optical access overlay

Agile Optical Networks

RJ45 patch panels provide a useful solution for cable management in data centers and other high-density environments. In the market, two types are offered like punch down and feedthrough patch panel. But consumers often find it’s difficult to make a decision on which one is better. This article is going to help your dilemma.

Punch Down Patch Panel

Punch down types are available in Cat5e or Cat6 patch panel. On the front plate, RJ45 ports (usually 24 ports) are used to directly connect Ethernet copper cable. All ports are numbered for easy identification. In the rear, it’s patch panel module with color markings for punching down Ethernet cable. Color coded labels are designed for T568A and T568B wiring configurations.

How to Punch Down a Patch Panel?

If you select punch down patch panel, firstly you need to terminate all cables into the patch panel.

First, strip the outside protective jacket about 3-6 inches from the cable with cable stripping tools.

Second, after removing the cable jacket, you should separate the wire pairs. Try to straighten the ends so that you can do the termination easily.

Third, place the cable wires into the slot on the patch panel. Choose a port on the patch panel to begin terminating. Usually we start with the 1st port. Then insert each wire into its own slot. Consider whether you will use T568A or T568B configuration. Don’t leave wires exposed to much or twisted to avoid weakening signal.

Fourth, terminate the wires. Lay all wires onto the slots and double check whether the wire matches the right configuration. Use a punch down tool with 110 blade to terminate each wire individually. The 110 blade should fully cover the wire on the patch panel. Push down the tool and cut the end of wire off.

Fifth, secure the cable to the patch panel with a zip tie if there are slots on the patch panel.

Sixth, inspect the wire. Once you’ve finished terminating the wires, use a cable tester to check if all the wires are correctly terminated.

When the punching down process is completed, you can install the patch panel into the racks with screws.

Feedthrough Patch Panel

Feedthrough patch panel provides patching without punching down the wires to the ports. There are generally Cat5e and Cat6 feedthrough patch panel configured in 1U (24 ports) or in 2U size (48 ports). Each feedthrough patch panel has both RJ45 ports on the front and rear side. And ports on front side are numbered for easy identification and installation. With feedthrough patch panel, the Ethernet patch cables can be inserted into the ports directly in an easy and fast way. The patch panel is quite suitable for high-density network system, which can protect cable and improve cable management efficiency.

Feedthrough Patch Panel Installation Steps

Install the feedthrough patch panels in lay racks or communication cabinets.

First, find an empty rack space.

Second, install the panel with supplied cuphead screws.

Third, insert the Ethernet patch cables into the front and rear ports.

Fourth, after patching all cables, use cable ties to secure the cables to lacing bar.

Punch Down Patch Panel and Feedthrough Patch Panel, Which One Is Better?

To use punch down patch panel or feedthrough patch panel, people are feel confused. Some recommends traditional one because they can find , while some prefer to feedthrough. Each one has its advantages and disadvantages. To decide which one to buy, you may consider the following factors:

Cost–feedthrough patch panel is more expensive than traditional patch panel. If your budget allows, you can purchase feedthrough patch panel.

Time–From the above content, the installation steps of punching down patch panel is obviously more complicated. Especially when you have lots of Ethernet cables to be punched down, it really takes a great deal of time. Using feedthrough patch panel can save you time without punching down procedures. However, it’s another case to small network.

Network Error Possibility–During terminating wires into the punch down patch panel slots, you may match the wrong configurations. That can lead to link fault. But you don’t need worry about this issue if you use feedthrough patch panel.

Suggestions for Buying Punch Down or Feedthrough Patch Panel

Punch down patch panel requires high techniques and carefulness. For small network, you are suggested to buy traditional patch panel on condition that you’re skilled at punching down wires. For big project, feedthrough patch panel is the first choice. Both patch panels are accessible in fiber-mart.COM. Come and find your appropriate RJ45 patch panel.