Connectivity Solutions for Duplex and Parallel Optics

In optical communication, duplex and parallel optical links are two of the most commonly deployed cabling structures. This post will discuss some specific connectivity solutions using 2-fiber duplex and 8-fiber/20-fiber parallel fiber optic modules.

Duplex and Parallel Optical Links

A duplex link is accomplished by using two fibers. The most commonly used connector is the duplex LC. The TIA standard defines two types of duplex fiber patch cables terminated with duplex LC connector to complete an end-to-end fiber duplex connection: A-to-A patch cable (a cross version) and A-to-B patch cable (a straight version). In this article the LC to LC duplex cables we use are all A-to-B patch cables. It means the optical signal will be transmitted on B connector and received on A connector.

two types of duplex-patch-cable

Figure 1: two types of fiber patch cables

A parallel link is accomplished by combining two or more channels. Parallel optical links can be achieved by using eight fibers (4 fibers for Tx and 4 fibers for Rx), twenty fibers (10 fibers for Tx and 10 fibers for Rx) or twenty-four fibers (12 fibers for Tx and 12 fibers for Rx). To accomplish an 8-fiber optical link, the standard cabling is a 12-fiber trunk with an MTP connector (12-fiber connector). It follows the Type B polarity scheme. The connector type and the alignment of the fibers is shown in figure 2.

8-fiber parllel system

Figure 2: parallel fiber (8-fiber) optic transmission

To accomplish a 20-fiber parallel optical link, a parallel 24-fiber MTP connector is used. Its fiber alignment and connector type is shown in figure 3.

20-fiber parallel system

Figure 3: parallel fiber (20-fiber) optic transmission
Duplex Fiber Optic Transmission Links (2-fiber to 2-fiber)

We will discuss the items required to connect two duplex transceivers in this part. These 2-fiber duplex protocols include but not limited to: 10GBASE-SR, 10GBASE-LR, 10GBASE-ER, 40GBASE-BiDi, 40GBASE-LR4, 40GBASE-LRL4, 40GBASE-UNIV, 40GBASE-FR, 100GBASE-LR4, 100GBASE-ER4, 100GBASE-CWDM4, 100GBASE-BiDi, 1GFC, 2GFC, 4GFC, 8GFC, 16GFC, 32GFC.

Duplex Direct Connectivity

When directly connecting two duplex SFP+ transceivers, an A-to-B type patch cable is required. This type of direct connectivity is suggested only to be used within a given row of racks/cabinets. Figure 4 shows two SFP+s connected by one LC to LC duplex patch cable.

2-fiber to 2-fiber direct connectivity Figure 4: 2-fiber to 2-fiber direct connectivity

Duplex Interconnect

The following figure is an interconnect for two duplex transceivers. An 8-fiber MTP trunk cable is deployed with 8-fiber MTP-LC breakout modules connected to the end of the trunk. It should be noted that the polarity has to be maintained during the transmission. And pinned connectors should be deployed with unpinned devices. Structured cabling allows for easier moves, adds, and changes (MACs). Figure 5 illustrates this solution.

2-fiber to 2-fiber interconnect (1)

Figure 5: 2-fiber to 2-fiber interconnect (1)

Item Description
1 LC to LC duplex cable (SMF/MMF)
2 MTP-8 to duplex LC breakout module (pinned)
3 8 fibers MTP trunk cable (not pinned)

Figure 6 is also an interconnect solution for SFP+ transceivers, but on the right side an 8-fiber MTP to 4 x LC harness cable and an MTP adapter panel are used instead. This solution works best when connectivity is required for high port count switch.

2-fiber to 2-fiber interconnect (2)

Figure 6: 2-fiber to 2-fiber interconnect (2)

Item Description
1 LC to LC duplex cable (SMF/MMF)
2 MTP-8 to duplex LC breakout module (pinned)
3 8 fibers MTP trunk cable (not pinned)
4 96 fibers MTP adapter panel (8 port)
5 8 fibers MTP (not pinned) to duplex 4 x LC harness cable
Duplex Cross-Connect

This solution is a duplex cross-connect. It will allow all patching to be made at the main distribution area (MDA) with maximum flexibility for port-to-port connection. Figure 7 illustrates the cross-connect solution for duplex connectivity.

2-fiber to 2-fiber cross-connect

Figure 7: 2-fiber to 2-fiber cross-connect

Item Description
1 LC to LC duplex cable (SMF/MMF)
2 MTP-8 to duplex LC breakout module (pinned)
3 8 fibers MTP trunk cable (not pinned)
Parallel Fiber Optic Transmission Links

We will discuss items required to connect two parallel (8-fiber or 20-fiber) transceivers in this part. These protocols include but not limited to: 40GBASE-SR4, 40GBASE-xSR4/cSR4/eSR4, 40GBASE-PLR4, 40GBASE-PSM4, 100GBASE-SR4, 100GBASE-eSR4, 100GBASE-PSM4, 100GBASE-SR10.

Parallel Direct Connectivity (8-fiber or 20-fiber)

When directly connecting two QSFP+ or QSFP 28 transceivers, an 8-fiber MTP trunk cable is needed. For directly connecting two CFP transceivers, a 24-fiber MTP trunk cable is needed.

8-fiber to 8-fiber direct connectivity

Figure 8: 8-fiber to 8-fiber direct connectivity
Parallel Interconnect (8/20-fiber)

Figure 9 shows an interconnect solution for two CFP modules (20-fiber). To break-out the CFPs to transmit the signal across an 8-fiber infrastructure, a 1 x 3 breakout harness (24-fiber MTP to three 8-fiber MTP) is required. To achieve an interconnect for two 8-fiber optics, we can replace the breakout harness by an 8-fiber MTP (pinned) trunk and the 24-fiber MTP trunk by an MTP (not pinned) trunk.

20-fiber to 20-fiber interconnect

Figure 9: 20-fiber to 20-fiber interconnect

Item Description
1 1×3 MTP breakout harness cable (24-fiber MTP to three 8-fiber MTP) (pinned)
2 96 fibers MTP adapter panel (8 ports)
3 24 fibers MTP trunk cable, three 8-fiber legs (not pinned)
Conclusion

This post gives brief introduction to the meaning of duplex and parallel optical link and presents some connectivity solutions for two duplex optics or two parallel optics. The corresponding items used in each solution are listed too. The transmission distance and working environment should be taken into account when applying each cabling solution. The parallel to duplex connectivity solutions will be discussed in the next post.

Functions of ONT and OLT in GPON Network

Gigabit passive optical network (GPON) is a point-to-multipoint access mechanism providing end users with the ability to consolidate multiple services onto a single fiber transport network. To realize this technology, many devices are used to support the network, such as optical splitter, ONT, OLT, etc. In this article, we will mainly discuss the functions of ONT and OLT in GPON network.

GPON

Functions of ONT

Optical network terminal (ONT) is an optical modem that connects to the termination point with an optical cable. It is used at end user’s premise to connect to the PON network on one side and interface with the user on the other side. Data received from the customer end is sent, aggregated and optimized by the ONT to the upstream OLT. ONT is also known as optical network unit (ONU). ONT is an ITU-T term, while ONU is an IEEE term. They both refer to the user side equipment in GPON network. A small difference between them might be the application locations. ONU can work in different temperature and weather conditions.

ONT

Functions of OLT

Optical line terminal (OLT) is the endpoint hardware equipment located in a central office of the PON network. Its basic function is to control the float information in optical distribution network (ODN) to go in both directions. OLT converts the standard signals used by fiber optic service (FiOS) to the frequency and framing used by PON system. In addition, it coordinates the multiplexing between the ONT conversion devices. There are two float directions for OLT system. One is the upstream direction to distribute different types of data and voice traffic from users. The other is the downstream direction which gets data, voice and video traffic from metro network or from a long-haul network and sends it to all ONT modules on the ODN.

OLT

How to Add or Delete ONT on OLT?
Way to Add ONT on OLT

If the password of an ONT is obtained, you can run the ONT add command to add the ONT offline. However, if the password is unknown, you can run the port portid ont-auto-find command in the GPON mode to enable the ONT auto-find function of the GPON port, and then run the ONT confirm command to confirm the ONT. When the ONT is added, you need to run the display ONT info command to see the current status of ONT. If the control flag is active, run state is online, config state is normal, and match state is match, then the ONT adding process is successful.

Way to Delete ONT on OLT

When you need to delete the ONT on OLT, please use the delete command. Then ONT configuration data is deleted with the deletion of the ONT and the online ONT is forced offline. ONT can’t be deleted when it has been configured with other services. You need to unbind the service first before delete the ONT.

How to Troubleshoot ONT?

To troubleshoot the ONT, you should remember that the most important step is to connect your computer directly to the ONT to see if the problem goes away. You can use the Ethernet cable for connection. If the problem still exists, you can reconnect the ONT power supply to clear its internal cache. If the network can not be restored after the above methods, maybe you need to consult professionals for help.

Conclusion

ONT and OLT are indispensable components in the GPON network system. If you are considering to purchase the ONT or OLT devices, FS.COM is a good place to go. Different types of ONT and OLT equipment are provided with high integration, flexible adaption and great reliability to meet all your requirements.

Overview of PON Network

PON has now became a popular network technology all over the globe. It first came in to being in 1995. The International Telecommunication Union (ITU) standardized two initial generations of PON – APON and BPON. And the advancement of PON network has never stopped. Until now, the recent PON standard of NG-PON2 has been put forward in 2015. With the maturity of PON, people are more easily accessible to networks today. But what does PON exactly mean? What’s the composition of PON network? The following part will give you the answer.

PON, also known as passive optical network, is a technology in telecommunication that implements a point-to-multipoint (P2MP) architecture. Unpowered fiber optic splitters are used to enable a single optical fiber to serve multiple end-points such as customers instead of providing individual fibers between the central office (hub) and customer. According to different terminations of PON, the network system can be divided into fiber-to-the-home (FTTH), fiber-to-the-curb (FTTC), fiber-to-the-curb (FTTB), etc. To be specific, a PON is made up of an optical line terminal (OLT) at the service provider’s hub and a number of optical network units (ONUs) or optical network terminals (ONTs) near end users. And “passive” is just used to describe that no power requirement or active electronic component is included for transmitting signals in the system.

PON

Here are some types of PON that have been used throughout the years:

1) APON

Its full name is asynchronous transfer mode (ATM) passive optical network. As the original PON system, APON uses ATM technology to transfer data in packets or cells of a fixed size. In APON, downstream transmission is a continuous ATM stream at a bit rate of 155 Mbps or 622 Mbps. Upstream transmission is in the form of bursts of ATM cells at 155 Mbps.

2) BPON

BPON, also known as broadband PON, is the improved version of APON. It adopts wavelength division multiplexing (WDM) for downstream transmission with the transmission rate up to 622 Mbps. It also provides multiple broadband services such as ATM, Ethernet access and video distribution. Today, BPON is more popular than APON.

3) EPON

EPON or Ethernet PON uses the Ethernet packets instead of ATM cells. Upstream and downstream rates of EPON are able to achieve up to 10 Gbps. It is now widely applied to FTTP or FTTH architecture to serve multiple users. With the advantages of scalability, simplicity, multicast convenience and capability of providing full service access, many Asian areas adopt EPON for their networks.

4) GPON

Gigabit PON is the development of BPON. It supports various transmission rates with the same protocol. The maximum data rate of downstream is 2.5 Gbps and upstream is 1.25 Gbps. It is also widely used for FTTH networks. But compared with EPON, its burst sizes and physical layer overhead are smaller.

Advantages of PON
  • Low cost, simple maintenance, flexible extensibility and easy to upgrade. And no need for power during transmission saves a lot for long-term management.
  • Using pure media network avoids the interference of lightning and electromagnetism. Thus PON network is suitable for areas under harsh conditions.
  • Low occupancy of central office resources, low initial investment and high rate of return.
  • As the P2MP network, PON is able to provide a large range of service to plenty of users.
Conclusion

PON network is for sure an effective solution for multiple network users. EPON and GPON are the most commonly deployed PON systems at present. Since people have been seeking for higher bandwidth provisioning, the capability of transmission will be greatly improved in the near future.

Comparison Between EPON and GPON

PON is the abbreviation of passive optical network, which only uses fiber and passive components like splitters and combiners. EPON (Ethernet PON) and GPON (Gigabit PON) are the most important versions of passive optical networks, widely used for Internet access, voice over Internet protocol (VoIP), and digital TV delivery in metropolitan areas. Today we are going to talk about the differences between them.

PON network

Technology Comparison

EPON is based on the Ethernet standard 802.3 that can support the speed of 1.25 Gbit/s in both the downstream and upstream directions. It is well-known as the solution for the “first mile” optical access network. While GPON, based on Gigabit technology, is designated as ITU-T G.983 which can provide for 622 Mbit/s downstream and 155 Mbit/s upstream. GPON is an important approach to enable full service access network. Its requirements were set force by the Full Service Access Network (FASN) group, which was later adopted by ITU-T as the G.984.x standards–an addition to ITU-T recommendation, G.983, which details broadband PON (BPON).

As the parts of PON, they have something in common. For example, they both can be accepted as international standards, cover the same network topology methods and FTTx applications, and use WDM (wavelength-division multiplexing) with the same optical frequencies as each other with a third party wavelength; and provide triple-play, Internet Protocol TV (IPTV) and cable TV (CATV) video services.

Costs Comparison

No matter in a GPON or in an EPON, the optical line terminal (OLT), optical network unit (ONU) and optical distribution network (ODN) are the indispensable parts, which are the decisive factor of the costs of GPON and EPON deployments.

The cost of OLT and ONT is influenced by the ASIC (application specific integrated circuit) and optic module. Recently, the chipsets of GPON are mostly based on FPGA (field-programmable gate array), which is more expensive than the EPON MAC layer ASIC. On the other hand, the optic module’s price of GPON is also higher than EPON’s. When GPON reaches deployment stage, the estimated cost of a GPON OLT is 1.5 to 2 times higher than an EPON OLT, and the estimated cost of a GPON ONT will be 1.2 to 1.5 times higher than an EPON ONT.

We all know that the ODN is made up of fiber cable, cabinet, optical splitter, connector, and etc. In the case of transmitting signals to the same number of users, the cost of EPON and GPON would be the same.

Summary

Nowadays, since many experts have different opinions on GPON and EPON. Thus, there is no absolute answer to determine which is better. But one thing is clear: PON, which possesses the low cost of passive components, has made great strides driven by the growing demand for faster Internet service and more video. Also, fiber deployments will continue expanding at the expense of copper, as consumer demands for “triple-play” (video, voice and data) grow.

Originally published at http://www.chinacablesbuy.com/comparison-between-epon-and-gpon.html

Optical Fiber Access Modes

Optical fiber broadband is a technology that converts electrical signals carrying data to optical signals and sends the optical signals through transparent glass fibers. The signal conversion process is completed through the optical modems installed on both ends of the optical fiber. Among various transmission media for the broadband network, optical fiber is an ideal one, which features in large transmission capacity, high transmission quality, long repeater spacing and low loss.

Optical fiber access technology provides users with high-speed bandwidth of 10 Mbps, 100 Mbps and 1000 Mbps that can be directly connected with the main crunodes of the internet. With high speed access to local area network (LAN) and high speed interconnection with internet, optical fiber access technology is applied mainly to LANs for business groups and intelligent residences. This article will introduce five common access modes of optical fiber.

Optical Fiber + Ethernet Access

Ethernet is a kind of technology for LANs and metropolitan area networks (MANs). When the optical fiber is connected with Ethernet, it is necessary to use switch, photoelectric converter and Cat5e.

Applications: residential areas and commercial buildings where generic cabling and system integration for optical fiber access are completed or easy to be implemented.

Optical Fiber + HomePNA Access

HomePNA is an industry standard for home networking over the existing coaxial cables and telephone wiring within homes. To connected optical fiber with the HomePNA, HomePNA switch (Hub) and HomePNA termination equipment (Modem) are important to connect optical fiber to the HomePNA.

Applications: residential areas and hotel buildings where generic cabling and system integration are undone or inconvenient to be done.

Optical Fiber + VDSL Access

Very-high-bit-rate digital subscriber loop (VDSL) is a technology providing data transmission over a single flat untwisted or twisted pair of copper wires and on coaxial cable. VDSL switch and VDSL termination equipment are essential to connect optical fiber with VDSL.

Applications: residential areas and hotel buildings where generic cabling and system integration are undone or inconvenient to be done.

FTTx + LAN Access

FTTx stands for fiber to the x, where x stands for home, curb, neighborhood, business, etc (as shown in the following figure). LAN refers to local area network. FTTx+LAN access aims at Gigabit Ethernet for the community, fast Ethernet for the building and 10 Mpbs Ethernet for the user.

fiber cable mix in access network

Applications: it is mainly applied to concentrated residential areas, enterprises and public institutions and universities and colleges. In FTTx+LAN, generic cabling is done in residential areas, high-class offices and student dormitories and teacher dormitories in universities and colleges.

Optical Fiber Access

Optical fiber access with transmission bandwidth from 2 Mbps to 155 Mbps is designed for enterprises and public institutions or groups who need the independent optical fiber-optic high-speed Internet. Since the bandwidth for upload and download is high, optical fiber access is suitable for such activities as remote instruction, tele-medicine and video conference.

Applications: it is applied to concentrated residential areas, communities and offices where generic cabling is done or easy to be implemented. Furthermore, it also applied to enterprises and public institutions or groups who need the independent optical fiber-optic high-speed Internet.

Optical fiber access is expanding due to the demand for broadband in consumer environment. Thus, products such as switches, photoelectric converters and transceivers used in optical fiber access are various in the market. As a professional supplier of optical communication products, Fiberstore supplies many kinds of products used in optical fiber access. Customers may choose the proper optical fiber optic access mode and optical fiber products according to their needs.