1GE ONU adopts Realtek RTL9601D chip solution

C-Data latest products 1GE ONU adopts Realtek RTL9601D chip solution

Recently, Shenzhen C-Data launched the latest products 1GE ONU. The ONU is based on Realtek RTL9601D chip solution, support GPON and EPON dual-mode passive optical network, and provide users up to Gigabit data access service through the PON network, and can be used for fiber access for home or SOHO business users. Features of high cost performance, high reliability and easy maintenance. The product is fully compatible with ITU G.984.x and IEEE802.3ah technical standards, and meets the technical requirements of operators for passive optical network terminal equipment.

C31 场景图

The ONU has an integrated white body and uses environmentally friendly, flame-retardant ABS material. The overall design conforms to the prevailing simple and fashionable style. The rear panel of the ONU is equipped with optical ports and LAN ports. The optical ports are used to connect to the network-side optical fiber link, and the electrical ports are used to connect to terminal devices such as PCs on the user side. The electrical port uses a standard RJ45 interface, 8-pin, to ensure the stability and reliability of data transmission. The equipment can be remotely configured and managed by the OLT, which is very convenient for installation and management. A set of LED indicators are provided on the top of the front of the fuselage, a POWER, an optical port, a LAN port, and system and link indicators. The working status of the equipment can be displayed to facilitate users to understand the operation of the equipment. The indicator light is yellow-green, clear, soft and pleasant. The fine heat dissipation holes on the sides and bottom of the shell are conducive to the dissipation of heat, which helps the internal chip to dissipate heat and ensure the stability of the product for a long time.

C-Data and Realtek have maintained a good cooperative relationship in a number of product areas. C-Data will take advantage of the performance and supply capacity of the RTL9601D chip to further consolidate the market position of C-Data ONU products and achieve a win-win cooperation.

different between HGU and SFU

Differences between HGU ONU and SFU ONU


The development of information technology and network shortens the distance between people and makes people increasingly inseparable from the network. PON (Passive Optical Network) technology, mainly composed of OLT, ODN, and ONU, as we all know, tends to mature and has been widely used so far. ONU is usually placed in the user’s home and varies with the diversity of users’ needs. As for the types of ONU, HGU ONU and SFU ONU are always come into our eyes, but few people can tell the difference between them. What exactly are SFU ONU and HGU ONU? You will get the answer in the rest of the article.

1.PON System

From the beginning, there is necessary to learn about PON as the critical part of ONU. PON (Passive Optical Network) is a kind of single-fiber bidirectional optical access network with a point to multipoint (P2MP) structure with a typical tree-type topology. The system composed of OLT (Optical Line Terminal), ONU (Optical Network Unit), and ODN (Optical Distribution Network) which provides a transmission channel, is what we call the PON system.

In the downlink direction (OLT to ONU), the signal sent by OLT reaches each ONUs through ODN. While in the uplink direction (from ONU to OLT), the signal sent by ONU only reaches OLT, not other ONUs. To avoid data conflict and improve network efficiency, the uplink direction adopts TDMA mode and manages the data transmission of each ONU. ODN provides an optical channel between OLT and ONU. The structure of PON is shown in Figure 1.1.

PON Structure for Reference

Figure 1.1 PON Structure for Reference

2.What is ONU?

ONU belongs to the terminal equipment of PON technology, playing an essential role in the PON system. ONU, in between the ODN and user equipment, provides the optical interface and the electrical interface to realize the processing, maintenance, and management of various photoelectric signals. There are currently user-side ONU devices, also known as the optical modem, directly installed in home.

The core layer, service layer, and public layer consist of the inner part of ONU. The core layer provides multiplexing and optical interface; the service layer mainly refers to user port, and the public layer ensures power supply and maintenance management. ONU is divided into active optical network units and passive optical network units. Generally, the equipment with an optical receiver, uplink optical transmitter, and multiple bridge amplifiers is called an optical node. The PON connects to the OLT which connects to the ONU through a single fiber. ONU can access various user terminals, such as set-top box, wireless router, TV, etc., and occupies functions of photoelectric conversion, maintenance, and monitoring.

3.Classification and Application of ONU

According to the application, ONU can be divided into six types, namely SFU (Single Family Unit) ONU, HGU (Home Gateway Unit) ONU, MDU (Multi-Dwelling Unit) ONU, SBU (Single Business Unit) ONU, MTU (Multi-Tenant Unit) ONU and CBU (Cellular Backhaul Unit) ONU. However, only SFU (Single Family Unit) ONU and HGU (Home Gateway Unit) ONU are used by the end-users in practical application.

These two types of ONUs will be introduced in the following.

(1)HGU(Home Gateway Unit)ONU

HGU ONU takes the Virtual Ethernet interface point (VEIP) as the partition point of the OMCI management domain and the non OMCI management domain (TR069, SNMP, etc.) in the data plane. The ME achieves management only through OMCI. The non OMCI management domain can only manage all services and functional modules under the VEIP. Only one VEIP is allowed in each HGU. ONU will report VEIP or PPTP (Physical Path Termination Point) when MIB is uploaded according to the type of the device, while HGU can only use and report VEIP rather than PPTP. OLT will judge the type of ONU devices according to the attribution of ONU type in ONU capability. Figure 3.1 shows the service process of HGU ONU.

Service Process of HGU ONU

Figure 3.1 Service Process of HGU ONU

HGU ONU, a home gateway with an uplink interface of the PON, is designed for the single family unit, which is similar to SFU ONU. Compared to SFU ONU, HGU ONU integrates the functions of ONU and RG to realize more complex control and management and provide Ethernet / IP service, VoIP service, and optional CATV service. HGU ONU has an Ethernet interface and pots interface, and WLAN interface, USB interface, and CATV RF interface are also available. Besides, TR-069 remote management and EMS local and remote management of physical layer and link layer related to PON interface are supported by HGU ONU that mainly used in FTTH scenarios.

Classified by the differences in service processes and interface numbers of ONUs, HGU ONUs has two specific forms shown in table 3-1.

Table 3-1 Specific Forms of HGU ONU

Number Interface Type Quantity of Ethernet Ports Quantity of POTS Port Quantity of WLAN Ports Quantity of USB Ports CATV RF Port
HGU-1A 1G 4 FE 2(or 1) 1(or 2) 1 optional
HGU-1B 10G/1G 4 GE or FE 2(or 1) 1(or 2) 1 optional
HGU-2A 1G 4(or 2)FE 2(or 1) 0 0 optional
HGU-2B 10G/1G 4(or 2)GE or FE 2(or 1) 0 0 optional


PPTP is that OLT directly sends VLAN data to each physical interface of ONU, fixing the whole processing process of data flow. VEIP virtualizes the total interface of an ONU. OLT and ONU conduct data docking through VEI. The services under VEIP are managed by ONU through their configuration. In short, PPTP is a LAN port, and VEIP is the virtual WAN port in HGU.

(2)SFU(Single Family Unit)ONU

SFU ONU only supports the OMCI management domain. PPTP is what SFU uses and reports, while VEIP is not available. The processing mode of OMCI configured data flow is different from that of RG flow. For OMCI data flow, there is a one-to-one mapping between the GEM port on the WAN side and the UNI port on the LAN side. All data packets can pass through without MAC address learning or forwarding. Wireless interfaces are not allowed in OMCI. Figure 3.2 shows the service process of SFU ONU.

Service Process of SFU ONU

Figure 3.2 Service Process of SFU ONU

SFU ONU is designed for a single family unit with broadband access terminal function without a more complex home gateway function from the perspective of application and ONU capacity. SFU ONU, mainly used in FTTH scenarios, has 1 or 4 Ethernet interfaces and is available for Ethernet / IP services, optional VoIP services (built-in IAD), or CATV services.

There are three specific forms of SFU ONU according to the difference of service process and interface quantity of ONU shown in Table 3-2.

Table 3-2 Specific Forms of SFU ONU


Interface type Quantity of Ethernet Ports Quantity of POTS Ports CATV RF Port
SFU-1A 1G 1 GE or FE 0 optional
SFU-1B 10G/1G 1 GE or FE 0 optional
SFU-2A 1G 4 FE 0 optional
SFU-2B 10G/1G 4 GE or FE 0 optional
SFU-3 1G 4 FE 2 optional

Note: SFU is suitable for commercial customers if TDM service is not included.

SFU ONU works under the bridging mode (layer 2 of ISO model), supports multiple VLAN functions, and its Ethernet port can be configured and managed by OLT through OMCI / OAM. Combined with a home gateway, SFU ONU is good at providing strong service capability. However, SFU ONU does not have a three-layer routing function and WAN connection configuration. The Single port 1GE ONU of C-Data is an exception as it has three-layer routing, static routing, PPPoE, DHCP function, etc.

(3)Functional Differences between HGU ONU and SFU ONU

EPON/GPON Standard IEEE 802.3/802.3ah


IEEE 802.3/802.3ah


Bridging /Routing Bridging/L2 Bridging/L2 and Routing/L3
WAN Configuration Not support Support
TR069 Function Not support Support
OLT to configure its  Ethernet Ports Support Not support
NAT Function Not support Support
Port Forwarding Function Not support Support
Loop Detection Function Support Not support
DHCP Server Not support Support
Wireless WIFI Not support Support


Number ONU Form ONU Model SFU/HGU
1 EPON & GPON & XPON 1GE / 1GE + CATV FD511G & FD701G series SFU ONU(with routing function)
2 EPON & GPON & XPON 1GE + Wi-Fi / 1GE + 1FE + Wi-Fi /

4GE + 2 pots + Wi-Fi (AC)

FD511GW & FD512XW & FD702XW & FD604GW & FD804GW series HGU ONU

1GE + 3FE / 1GE + 3FE + CATV / 4GE

FD50X & FD704X & FD504G series SFU ONU (without routing function)



Both SFU ONU and HGU ONU have their advantages and disadvantages. The truth is that the main role of ONU is to provide end-users with bandwidth access, playing a vital role in the “last mile” of the access network so that end users can better enjoy the network. Therefore, choosing the right ONU should depend on your network environment.

As a professional ONU supplier, C-Data Shenzhen will focus more on the accumulation and research of technical knowledge to improve our ONU products and meet the customers’ needs for unimpeded network experience. Moreover, C-Data Shenzhen will step further with our customers by improving the quality of products and services without delay.

epon to gpon keep xpon

What is xPON(EPON/GPON dual mode) ONU?

Brief video ☞  What is xPON(EPON/GPON dual mode) ONU?

In the access network, Passive Optical Network(PON) is the best transmission medium to realize triple-play and solve the “last mile” of the information highway. EPON and GPON are the most prevailing and mature access network standard in the PON network. EPON, a kind of mainstream broadband access technology based on IEEE 802.3ah standard, realizes the integrated service access of data, voice, and video through a single optical access system, being economical. As for GPON (Gigabit Passive Optical Network), it is the latest generation of broadband access technology based on ITU -TG.984.x standard. GPON is regarded by most operators as the ideal technology to realize broadband and integrated transformation of access network services because of its high bandwidth, high efficiency, extensive coverage, rich user interface, and so on. Therefore, communications equipment manufacturers have developed products that compatible with both EPON and GPON standards, commonly known as xPON.

1. Overview of xPON ONU

It is well-known that the passive optical network system is composed of an optical line terminal (OLT), optical distribution network (ODN), and optical network unit (ONU). xPON ONU is an optical network unit that supports both EPON IEEE 802.3ah standard and GPON ITU-TG.984.x standard, which means it can be used in both EPON and GPON networks. xPON ONU also can automatically switch in EPON or GPON mode.

2.xPON ONU Technology

2.1 Software

At first, two concepts of PLOAM and MPCP are brought to you.

In GPON, the physical layer OAM (PLOAM) channel has to be built by ONU and OLT before ONU wants to register with OLT (it calls the registration phase). PLOAM channel is a formatted information system carried by GTC lock in the designated location. It is used to transmit other PMD (Physical Media Dependent) and GTC (GPON Transmission Convergence) management information that is not sent by the embedded OAM channel. OMCI channel is used to manage the business definition of the GTC upper layer. GTC must provide a transport interface for OMCI. An optional channel, including defining the transport protocol ID (Port-ID), is offered by GTC according to the configuration of the device.

In EPON, ONU and OLT have to establish an MPCP control mechanism if ONU wants to register with OLT (it calls the registration stage). MPCP (Multi-Point Control Protocol) is the protocol of the EPON MAC control sublayer. MPCP defines the control mechanism between OLT and ONU to coordinate the effective sending and receiving of data.

Building PLOAM channel in GPON and MPCP control mechanism in EPON are both called the registration stage.

xPON ONU will be embedded in a special process to detect the optical signal of the OLT downlink to identify whether it is GPON or EPON mode because EPON and GPON have different interaction protocol messages and fields, which give aid to ONU’s identification in the registration phase. If the result of identification is inconsistent with the PON mode of ONU, ONU will restart automatically to switch to the PON mode consistent with the current network.

2.2 Hardware

Usually, ONU optical module is used in ONU equipment composed of burst mode laser driver, receiving limiting amplifier, BOSA, MCU, APD boost circuit, etc.

There are two kinds of lasers in the ONU module: FP and DFB.

As the receiver receives the signal continuously, it needs a special limiting amplifier to amplify the electrical signal converted from PD. APD-TIA and PIN-TIA are two kinds of receivers.

According to the performance requirements, 1310nm DFB LD and InGaAs Super-TIA receiver with 1490nm WDM filter is required for GPON ONU optical module. As for EPON ONU optical module, 1310nm FP LD and InGaAs PIN-TIA receiver with 1490nm WDM filter is required.

Burst transmitters and receivers are usually used in optical devices, but it is a key technical difficulty for all TDM-PON. There are great differences in timing requirements when optical devices deal with burst transmitters and receivers because of the different transmission protocols of EPON and GPON. In fact, the uplink burst timing requirements of GPON are much more stringent than EPON’s. As shown in Figure 1, the setting time required by the burst reception threshold of GPON is within 96 bytes, i.e., 77ns, while that of EPON is 400ns. Moreover, GPON also treats the on-off time of the laser in the burst emission control of ONU more strictly.

Figure 1

To sum up, GPON optical devices are generally used in xPON ONU. As the saying goes, “technology is downward compatible”, GPON optical devices are used to be compatible with the network environment of EPON.

3.Applications and Advantages of xPON ONU

3.1 Compatible with the existing network

xPON ONU can work on EPON or GPON mode. It can automatically identify whether the OLT is EPON type or GPON type and switch the operation mode . Therefore, whether the current network of Operators or ISPs is EPON or GPON, xPON ONU can run in it.

3.2 Upgrade deployment faster

Because the implementation of the EPON network is earlier than the GPON network, the EPON network accounts for a large proportion of the current network. However, the EPON network will be gradually replaced by the GPON network due to the advantage of bandwidth.

xPON ONU plays an important role in the transition from the EPON network to the GPON network. When operators decide to upgrade to GPON, a more smooth network transition, and huge upgrade cost saving can be achieved by only replacing the  EPON OLT to GPON in head-end without any operations for the user end.


3.3 Investment protection

The original EPON ONU and EPON OLT equipment must be eliminated in the process of system upgrading from EPON to GPON. But xPON ONU can avoid the elimination as it is compatible with both EPON and GPON standard, which greatly protects the investment of users.

3.4 conducive to network operation and maintenance management

xPON ONU makes EPON and GPON transparent and provides a unified interface for the upper management after the differences between EPON and GPON are blocked. Thus, no matter the terminal is EPON or GPON, the terminal configuration is the same. In this case, the network administrator only needs to focus on business management, which greatly improves the operation and maintenance management efficiency.

4.Types of C-Data xPON ONU

Number ONU Configuration ONU Model PON Mode Supporting
1 EPON&GPON&XPON 1GE/1GE+CATV FD511G&FD701G series 1. Support automatic recognition of EPON / GPON mode

2. Support manual switching of EPON/GPON mode

2 EPON&GPON&XPON 1GE+wifi/1GE+1FE+wifi/


FD511GW&FD512XW&FD702XW&FD604GW&FD804GW series 1. Support automatic recognition of EPON / GPON mode

2. Support manual switching of EPON/GPON mode



FD50X&FD704X&FD504G series 1. Support automatic recognition of EPON / GPON mode

2. Support manual switching of EPON/GPON mode

5. Prospect and Summary

xPON ONU has overwhelming advantages in compatibility, anti-interference, bandwidth characteristics, access distance, maintenance management, and so on. It is prevailing in the market and got highly concerned by ISP regarding its application. xPON ONU may become the mainstream in the next few years from the current situation given that the EPON network has been basically solidified, and only with the support of xPON ONU can the transition from EPON to GPON network be successful.

As a professional FTTH broadband access product supplier, Shenzhen C-Data Technology Co., Ltd. will keep abreast of the market trends and demand to produce better products for the Internet industry.




PON Protection Switching Technology


With the increase of PON networks’ services, it is necessary to implement PON protection switching technology to ensure the stability of engineering applications stability and deal with service interruptions caused by various communication failures. This article mainly introduces several different PON protection technologies on OLT and describes some implementation points based on a dual PON port protection solution. The ONU remains online, and services are not interrupted before and after the solution is switched. And the delay is less than 100 ms, which greatly guarantees network stability.


PON (Passive Optical Network) is an optical fiber broadband access technology covering the last mile. It only needs to install a simple optical splitter at the optical branch point, which has the advantages of saving optical cable resources, bandwidth resource sharing, no electromagnetic interference, equipment safety, high performance, and low-cost comprehensive network construction. Among them, saving the backbone fiber is a huge advantage of the PON system, but it also brings greater risk. Once the backbone fiber in the PON system fails, it will cause all-optical network units (ONUs) connected to the backbone fiber interrupted simultaneously.

Besides, the system also has the probability of the optical module’s failure and the failure of the port, which is connected to the main fiber. To ensure the service’s stability in engineering applications and deal with the service interruption caused by various communication failures, an efficient and reliable protection switching solution is required. When the backbone fiber fails, the protection switching can be realized in the shortest possible time and recover the services without affecting users’ use.

1、Introduction to PON Protection Switching Technology

   1.1 PON ProtectionOverview

At present, the commonly used PON protection technologies are the four protection types A, B, C, and D defined in the ITU-TG.984 standards. The protection range of types A and B is the protection from the PON port of the OLT to the optical splitter. The difference between the two is whether the OLT’s PON port is included in the protection range. The protection scope of types C and D is comprehensive protection from the PON port of the OLT to the PON port of the ONU. The difference between the two is whether the ONU’s PON port is included in the protection scope.

  1.2 PON Protection Type A

PON protection type A mainly uses a single PON port for the OLT, which has a built-in 1×2 optical switch for the optical module’s gating and then switches the working line. In the optical distribution network (ODN), a 2: N optical splitter is used, and two relatively independent and mutually backup optical fiber links are established between the optical splitter and the OLT. The OLT will detect the line status periodically. When the optical link fails, it switches to the backup optical link.

PON protection switching technology (1)

  1.3 PON Protection Type B

The OLT’s two PON ports in the PON protection type B adopt independent PON MAC chips and optical modules and are identified as the main PON port and the backup PON port. The main PON port is in a working state, and the standby PON port is in a cold backup state.

In ODN’s optical splitter use, two relatively independent and mutually backup optical fiber links are simultaneously connected between the optical splitter and the OLT. The OLT ensures that the main PON port’s business information can be backed up synchronously and periodically inspect line status and PON port operating status. When the main fiber link or PON port fails, the OLT immediately switches to the backup PON port and fiber link. The backup PON port can maintain the ONU’s service attributes unchanged, and the service is transferred to the backup link.

pon protection switching technology(2)

   1.4 PON Protection Type C

PON protection type C uses two PON ports on the OLT, and the main standby PON ports are mutually hot backup. ONU uses a PON MAC and different optical modules; a 1×2 optical switch is built in front of the PON port. Two 1: N optical splitters are used to establish two independent and mutually backup optical fiber links between ONU and OLT. The OLT guarantees that the main PON port’s service information can be backed up to the backup PON port simultaneously. Both the ONU and the OLT detect the link status and decide whether to switch according to the link status.

pon protection switching technology(3)

  1.5 PON Protection Type D

In PON protection type D, OLT dual PON ports, ONU dual PON ports, backbone fiber, optical splitter, and distribution fiber are all dual redundant. Both the main and standby OLT PON ports are in working condition. OLT guarantees that the active PON port’s service information can be backed up to the backup PON port synchronously. As a result, the backup PON port can maintain the ONU’s service attributes unchanged during the protection switching process.

ONU uses different PON MAC chips and different optical modules. The ONU should ensure that the primary PON port’s service information can be backed up to the backup PON port simultaneously so that the ONU can maintain the local service attributes during the PON port protection switching process. The ONU’s main and backup PON ports are in a working state. The backup PON port does not need to perform the ONU’s initialization configuration and service attribute configuration during the PON port protection switching process. Both ONU and OLT detect the link status and decide whether to switch according to the link status.

pon protection switching technology(4)

  1.6 Choice of 4 Types of PON Protection

The four PON protection types A, B, C, and D protection solutions are introduced above. The OLT’s two PON ports in Type A use 1 PON MAC chip, which is connected to 2 optical modules through a 1×2 switch to realize 2 PON ports’ protection. This type is only applicable to the protection in the same PON board. Although the C and D protection types protect the entire network, making the system the best reliable, the protection cost is too high. Simultaneously, ONU equipment also needs to support the corresponding PON protection function, which only high-end users can afford. So, it is hardly used in actual projects.

Considering the access cost and practicability, Type B protection is more economical and practical. In Type B protection, the OLT’s two PON ports adopt independent PON MAC chips and optical modules to realize the protection of two PON ports, which is suitable for protection between any 2 PON ports of the same OLT.

2、Realization of PON Protection Switching Function

   2.1 PON Protection Group

The PON protection group consists of two access PON ports. The members of the protection group have two roles: work and protect. One is a working port, and the other is a protecting port. Under normal working conditions, the working port carries services. When the optical fiber link in the working port fails, the system automatically switches the working port’s service to the protected port to ensure service transmission.

  2.2 Status of Protection Group Member

There are two states of protection group members: active and standby. The port in the active state forwards data and the port in the standby state does not forward data.

  2.3 Type of Switching

There are two types of protection group switching: automatic switching triggered by failure and protection switching performed manually. The manual protection switching performed is also called forced switching:

(1) Automatic switching means that the OLT and ONU do not need human intervention to automatically switch the optical fiber link when the switching conditions are met.

(2) Forced switching refers to operating force-switch on the OLT so that optical link switching occurs regardless of whether the designated target member is normal.

3、 Key Points of PON Protection Switching Technology

To ensure smooth service transition after PON protection switching, the PON protection group’s initial configuration needs to be issued synchronously. The dynamic data during the operation of the protection group also needs to be synchronized. Initial configuration refers to the primary PON port’s static service configuration information in the protection group, such as VLAN, bandwidth, voice configuration, and multicast video service configuration. Dynamic data includes the MAC address learning table, multicast member group information, DHCP binding table, key information.

  3.1 Configuration Synchronization

The configuration of the same ONU on the two PON ports in the protection group must be synchronized. The key to configuration synchronization is as follows:

1)  All ONUs authenticated on the primary PON port should be synchronized to the standby PON port, allowing the ONU to update its online state structure. The active PON port module should also synchronize the configuration status information with the standby PON port module to avoid repeated configurations and affecting services.

2)  Dynamic data synchronization: Dynamic data synchronization refers to synchronizing data from the PON port in the working state to the PON port in the standby state when the data changes. It requires a host CPU for real-time data synchronization.

  3.2 Service Recovery

After performing the PON port’s active/standby switchover, the original standby PON port becomes the active port. All PON related configurations and ONU configurations under the PON port should be the same as the original working PON port. After the PON protection switch is completed, all services can be automatically restored when the new working PON port is normally available.

  3.3 PON Protection Switching of C-Data OLT Products

With more and more types of services carried by PON networks, to ensure the stability of the services in engineering applications, C-Data combines PON protection in actual engineering, considering the access cost and practicality, and has fully supported PON for protection type B. The user does not need to pay attention to which PON port of the protection group is currently working. All operations are based on the main PON port. When the protection switching is triggered, the standby port state changes to the working state and replace the main PON port to continue to carry services.

As far as we know, the PON protection function implemented by OLT of some manufacturer does not actually implement protection switching but backs up the configuration of the active port to the backup port. The result is that all ONU will be disconnected after the switching, and the service will be lost, which will cause great distress to operation and maintenance personnel. However, our OLT solutions has achieved true protection switching. When the PON port is fully loaded with ONU, ONU can be kept online before and after the switching without service interruption, ensuring network stability safely and quickly.


With the popularization of information technologies such as big data, artificial intelligence, cloud computing, and the internet of things, PON technology efficiently supports various industries’ digital development by its technical reliability and practicality and relatively reasonable price advantages. As a professional supplier of network access products, C-Data will provide reliable and stable network deployment to the industries worldwide and apply more PON protection technologies to products. At the same time, it is great for consumers to choose OLT solutions that supports the PON protection of C-Data and jointly promoting the steady development of global digital networks.

2021 happy new year(1)

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Best wishes for the holidays and happiness throughout the New Year.2021 happy new year

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I have received many Christmas gifts, but the best one is meet you,merry Christmas!Happy new year!




IPv6 Technology for C-Data ONU Products

The rapid development of the Internet had brought a large number of intelligent terminals to our home and increasingly exhausted the IPv4 address resources we are using. Although NAT technology helps to delay the speed of the IPv4 address consumption, the world Internet technology is still developing towards IPv6 technology which has become one of the key basic technologies required by 5G, cloud computing and Internet of things technologies.

In the past two years, the world has advocated and accelerated the deployment of IPv6 technology to meet the urgent needs of the connection of massive intelligent terminals, the innovation of technology industries, and the enhancement of network security capability. Almost all ISP/Operators are building the next generation of the Internet based on IPv6 technology.

C-Data, as a professional manufacturer in access network technology, will discuss the following related topics to help you understand IPv6 technology more comprehensively.

  • Overview of IPv6 Technology
  • Transition Technology from IPv4 to IPv6
  • Relevanceof C-Data ONU to IPv6 Technology
  • C-Data ONU products supporting IPv6 technology
  • Expectation of IPv6 Technology in The Future
  1. Overview of IPv6 Technology

1.1 What is IPv6?

IPv6 (Internet Protocol Version 6) is the next generation of the current Internet Protocol (IPv4). Composed of 128-bit binary numbers, IPv6 provides a huge resource of IP address enough for every living creature and even every grain of sand on the earth to be assigned one or more IP addresses. IPv6 is to divide the 128-bit address into segments per 16 bits, and each segment is separated by colons when converted into hexadecimal digits.

An example of IPv4 address:

An example of IPv6 address: 2002:0db8:85a3:08d3:1319:8a2e: 0370:7344

1.2 Why use IPv6 technology?

IPv4 technology is a 32-bit binary address, which can address 16 million networks and 4 billion hosts. However, with the adoption of A, B, and C addressing methods, the number of available network addresses and host machines is greatly reduced. Moreover, as the core technology and about 3 / 4 IP resources are mastered by European and American countries due to their developed Internet, many developing countries fall into the predicament of insufficient IP address resources. In fact, with the increasing number of global Internet users and the vigorous development of intelligent terminals and network technology, the lack of IP address resources will seriously restrict the application and development of the Internet in many countries around the world.

1.3 Current situation of IPv6 Technology

If to realize the complete transition from IPv4 to IPv6, it requires the network software, hardware, and terminal equipment in the global Internet infrastructure to support IPv6 protocol, which will involve a lot of transformation work. Although IPv6 technology has been proposed as early as the 2010 year, it has only been promoted by governments and major ISP/Operators in recent two years. Moreover, the long-term coexistence of IPv4 and IPv6 is still a compatibility issue that we need to consider.

1.4 What are the advantages of IPv6 over IPv4?

Compared with IPv4, IPv6 has the following advantages:

  • Larger address space. The IP address length of IPv4 is 32; that is, there are 2^32-1 addresses. While the IP address length of IPv6 is 128, that is, there are 2^128-1 addresses.
  • Smaller routing table. Compared with IPv4, IPv6 packet header contains half of the fields, and all fields are aligned with 64-bit boundaries, which greatly improves the processing speed.
  • Enhanced multicast support and streaming support. There is no terrible broadcast storm caused by the IPv4 as the multicast support, and streaming support provide a good opportunity for the development of multimedia services.
  • Higher security. Users can encrypt the data in the network layer and verify the IP message while using IPv6, which greatly enhances network security.

In view of the advantages of IPv6, IPv6 will eventually completely replace IPv4 and occupy a dominant position on the Internet after a long period of coexistence of IPv4 and IPv6.

  1. Transition technology from IPv4 to IPv6

Since IPv6 will eventually replace IPv4, how to achieve a network environment fully IPv6 compatible? The initial network transformation from IPv4 to IPv6 reveals that there is a thorough adjustment from protocol to hardware, including the client and server. Therefore, the issue of backward compatibility has been taken into account by IETF when designing IPv6 from the very beginning. The ISP/Operator will provide an intermediate node and uses DNS64 / NAT64 technologies, which are responsible for protocol conversion to connect the link between IPv6 and IPv4.

2.1. Tunnel technology for the initial transition

At the tunnel entrance between the IPv6 and the IPv4, the router encapsulates the entire IPv6 datagram into the data field of the IPv4 datagram. The source address and destination address of the IPv4 packet are respectively the tunnel entrance and exit of IPv4 addresses. At the exit of the tunnel, the IPv6 packet is taken out and forwarded to the destination node.


2.2. Dual-stack technology for IPv4 / IPv6 coexistence

Dual-stack technology is an effective technology for the transition from IPv4 to IPv6. The nodes in the network support both IPv4 and IPv6 protocol stacks. The source node selects different protocol stacks according to the different destination nodes while networking equipment according to the protocol type of the message. A dual-stack can be implemented on a single device or a dual-stack backbone. For a dual-stack backbone network, all devices must support IPv4 / IPv6 protocol stack at the same time, and the interface connecting the dual-stack network must be configured with both IPv4 and IPv6 addresses.


  1. Relevance of C-Data ONU to IPv6 Technology

The IPv6 network is divided into a backbone network and an access network. As the backbone network carries a lot of IPv6 services, most ISP/Operators have completed the deployment of the IPv6 backbone network but the access network is used for the access of terminal users. Nowadays, given that almost every family is connected with optical fiber, how to integrate IPv6 function on PON products to solve the problem of IPv6 compatibility is a difficult problem faced by many a ONU manufacturer.

In order to realize fast and easy access to IPv6 network in FTTH and adapt to the needs of global IPv6 network development, C-Data has spared no effort to make ONU support IPv6 service, and a graphical interface is released for end-users to use IPv6 on C-Data ONU easily. Furthermore, C-Data ONU supports IPv4 / IPv6 dual-stack transition technology and has revived the Anatel certification to meet the IPv6 networks in most of the countries. Some countries’ networks have used C-Data ONU as IPv6 network access.

There are two IPv6 network scenarios of C-Data ONU discussing as follows:

Scenario 1: transparent transmission of IPv4 / IPv6 services by ONU bridge mode

This scenario is mainly used for PPPoE or IPoE of IPv4 / IPv6, with user computers attached to ONU devices or wireless routers attached to ONU devices. Both OLT and ONU during transmission act as middle transmission devices, and only bridge mode is configured to transparently transmit IPv4 / IPv6 services. It is worth noting that whether the intermediate OLT and ONU devices support transparent IPv6 services needs to be considered because there are many OLT and ONU devices on the market that do not support transparent transmission of IPv6 services.


Scenario 2: ONU routing mode carries IPv4 / IPv6 services

In this scenario, the routing mode on ONU should support PPPoE or IPoE services of IPv4 / IPv6, and then allocates IPv4 / IPv6 address to the attached user computer or wireless router through DHCPV4 / DHCPv6 to realize the network access of IPv4 / IPv6. It is available for the OLT devices and the transparent transmission of IPv4 / IPv6. In this scenario, many manufacturers’ ONU products are difficult to implement. However, a lot of ONU manufacturers fail to apply their products to this scenario as there is a couple of issues to figure out, such as the compatibility of IPv6, the implementation of IPv6 Routing, the coexistence of IPv4 and IPv6, and the distribution of IPv6 address.



  1. C-Data ONU Products Supporting IPv6 Technology
No. ONU Form ONU Models Function Description
1 EPON&GPON&XPON 1GE/1GE+CATV FD511G&FD701G Series 1. Support PPPoE / IPoE, DHCPv6, IPv4 / IPv6 dual stack functions of IPv4 and IPv6 in routing mode;

2. Support transparent transmission of IPv4 / IPv6 service in bridge mode.

2 EPON&GPON&XPON 1GE+wifi/1GE+1FE+wifi/


FD511GW&FD512XW&FD702XW&FD604GW&FD804GW Series 1. Support PPPoE / IPoE, DHCPv6, IPv4 / IPv6 dual stack functions of IPv4 and IPv6 in routing mode;

2. Support transparent transmission of IPv4 / IPv6 service in bridge mode.



FD50X&FD704X&FD504G Series 1. Only transparent transmission of IPv4 / IPv6 service in bridge mode.



  1. Expectation of IPv6 Technology in the Future
  • The global network will build new information technology facilities based on IPv6 and give priority to the use of IPv6 in 5G, the Internet of things, and the industrial Internet.


  • Technical standards such as IPv6 + and SRv6 will be derived from IPv6 single stack. The application mode will be innovated to increase the pilot and commercial applications under the coordination with industrial chains.


  • Intelligent ultra-wide, intelligent connection and intelligent operation and maintenance are the main characteristics of the future IP network. IPv6 is the best choice for an intelligent IP network.



AI, big data, cloud computing, and the Internet of things technologies have an important connection with TCP / IP protocol. IP is the network layer protocol standardizing the exchange and routing of Internet packet information. As an infrastructure, IPv6 will construct a new Internet era.


As a professional FTTH broadband access product supplier, C-Data will accelerate the deployment of the IPv6 network together with the global ISP/Operators and apply more IPv6 technologies to the products. If you are interested in IPv6 technology, C-Data welcomes the chance to provide C-Data ONU for you and discuss IPv6 technology together.