Feb 15

Do You Know the Difference Between Hub, Switch & Router?

When computers, network devices or other networks are required to be connected, hubs, switches and routers are the bridges to link them together. All the three types of devices can perform the same function, and technicians sometimes may use the terms interchangeably. However, this will make people confuse whether they are the same thing or different from each other. This post is going to explore the actual meanings of hub, switch, router and what they are used for.

Overview of Hub, Switch & Router

A hub is to sent out a message from one port to other ports. For example, if there are three computers of A, B, C, the message sent by a hub for computer A will also come to the other computers. But only computer A will respond and the response will also go out to every other port on the hub. Therefore, all the computers can receive the message and computers themselves need to decide whether to accept the message.

hub network


A switch is able to handle the data and knows the specific addresses to send the message. It can decide which computer is the message intended for and send the message directly to the right computer. The efficiency of switch has been greatly improved, thus providing a faster network speed.

switch network


Router is actually a small computer that can be programmed to handle and route the network traffic. It usually connects at least two networks together, such as two LANs, two WANs or a LAN and its ISP network. Routers can calculate the best route for sending data and communicate with each other by protocols.

router network

What Is the Difference?
Hub Vs. Switch

A hub works on the physical layer (Layer 1) of OSI model while Switch works on the data link layer (Layer 2). Switch is more efficient than the hub. A switch can join multiple computers within one LAN, and a hub just connects multiple Ethernet devices together as a single segment. Switch is smarter than hub to determine the target of the forwarding data. Since switch has a higher performance, its cost will also become more expensive.

Switch Vs. Router

In the OSI model, router is working on a higher level of network layer (Layer 3) than switch. Router is very different from the switch because it is for routing packet to other networks. It is also more intelligent and sophisticated to serve as an intermediate destination to connect multiple area networks together. A switch is only used for wired network, yet a router can also link with the wireless network. With much more functions, a router definitely costs higher than a switch.

Hub Vs. Router

As mentioned above, a hub only contains the basic function of a switch. Hence, differences between hub and router are even bigger. For instance, hub is a passive device without software while router is a networking device, and data transmission form in hub is in electrical signal or bits while in router it is in form of packet.

Which One Should I Buy?

Whatever device you use for your network, you must make sure it can perform all the functions required by the network. As for performance, wireless router is recommended because it allows different devices to connect to the network. If you have a limited budget, switch is a good solution with relatively high performance and lower cost.


Although sometimes specialists alternatively use hub, switch or router to describe these devices, they still have their own differences. Understanding their distinctions can be helpful to find the most appropriate device for your network.

Feb 09

How Will SDN Change the Future Network?

Traditional networks are usually built with tiers of Ethernet switches in a tree structure. However, the development of mobile devices, server virtualization and cloud computing service has driven the need for dynamic computing and storage in data centers. Thus, the concept of software-defined networking (SDN) was put forward to construct a more flexible and agile network. This technology has widely caught people’s attention in the industry over the years. In this post, some basic knowledge about SDN will be introduced to help you have better understanding.

Definition of SDN Architecture

SDN is a developing network architecture that aims to directly program the network computing. Through the open interfaces and abstraction of lower-level functionality, this approach allows the network administrators to programmatically initialize, control, change and manage network behavior dynamically. SDN is different from the traditional network architecture whose network devices are based on both control plane and data plane. Instead, SDN puts the control plane on the SDN controller to communicate with a physical or virtual switch data plane through the OpenFlow protocol.


Features of SDN

Here are some fundamental features of the SDN architecture:

  • Instantly programmable: Network control is directly programmable for it is decoupled from forwarding functions.
  • Agile: Administrators can dynamically adjust network-wide traffic flow to meet changing needs.
  • Centralized management: Network intelligence is centralized in SDN controllers that maintain a global view of the network.
  • Programmatically configured: Network managers can configure, manage, secure, and optimize network resources very quickly by dynamic, automated SDN programs.
  • Open standards-based and vendor-neutral: SDN simplifies network design and operation since instructions are provided by SDN controllers instead of multiple, vendor-specific devices and protocols.
Basics of OpenFlow

OpenFlow is a type of communication protocol that provides access to the forwarding plane of a network switch or router over the network. It is considered to be the first SDN standard, which enables network controllers to determine the path of network packets across a network of switches. In order to work in an OpenFlow environment, all the equipment should support the OpenFlow protocol to communicate to an SDN controller.


What Benefits Will OpenFlow-Based SDN Bring to Network?
  • Point 1, SDN controller can get centralized control of OpenFlow-enabled devices from any vendors instead of managing the devices from different vendors separately.
  • Point 2, OpenFlow-based SDN provides a flexible network automation and management architecture, and can develop a variety of automated network management tools to replace the current manual operation which greatly reduces the complexity.
  • Point 3, SDN increases higher rates of business innovation and allows IT network operators to meet specific business needs and variable user needs in real time by explicitly programming or reprogramming the network.
  • Point 4, SDN enables IT to define the configuration network and develop management policies at a higher level and distributes the information to the network infrastructure through OpenFlow, which has increased the network reliability and security.
  • Point 5, OpenFlow’s flow control model allows IT to deploy network policies at a granular level which is a higher abstraction and automated deployment level including session-level, user-level, device-level and application-level.
  • Point 6, through centralized network control and network application status information, SDN can provide better dynamic user experience.

Future network will depend on more and more software to accelerate the pace of network innovation. SDN is committed to changing the current static network into a dynamic and programmable one. With so many advantages and industrial potentiality, SDN will definitely become the new standard of future network.

Jan 30

Computer Networks Comparison Between LAN & WAN

When setting up the wireless router at home, you may notice that there are different ports at the back of router noted with LAN or WAN. If you are totally new to this, then understanding the differences between LAN and WAN technologies is fairly important. This article will solve your confusion about these network terms.


What Is LAN?

LAN is the abbreviation of local area network. As a simple and original network, LAN is widely used in different kinds of places for short range computer connections. It is a computer network built within a restricted area. LAN network has its own network devices and local interconnections. Applications of LAN can always be found in the residence, school, laboratory, university campus or office. All the computers are linked in the same general location. A local area network is considered to be private and maintained by a single group of people.

local area network

What Is WAN?

WAN refers to wide area network. It is a computer network with a large geographical coverage. The essence of WAN is to allow a network to be carried out without the limitation of location. The Internet that we use every day is a good example of WAN network. As its name suggests, WAN is very wide that can across a town, a region, a country or even the whole world. It is often used by business and government agencies to make strong network communication among employees, clients, supplier and buyers from various parts of the world.

wide area network

Differences Between LAN & WAN

Here are some major differences between LAN and WAN computer networks.

  • Point 1, cover ranges of LAN and WAN networks are different. LAN connects computers in a small physical area, while WAN connects larger areas situated in different geographical locations.
  • Point 2, network speeds of LAN and WAN are varied. WAN is typically slower than LAN due to the distance data must travel. The maximum speed of LAN is 1000 Mbps while WAN can only reach 150 Mbps.
  • Point 3, as for the security level, LAN seems to be better than WAN. Because WAN involves more people into the interconnection, there is a greater possibility of network issues.
  • Point 4, due to the smaller network coverage, setup and maintenance costs for LAN are usually lower than WAN.
Other Computer Network Types

Apart from the common LAN and WAN computer networks, there are also many other types.

WLAN: wireless local area network is a type of LAN that uses wireless technology to connect computers or devices to the router.

MAN: metropolitan area network is larger than LAN and smaller than WAN to connect nodes located in the same metro area.

SAN: storage area network provides access to consolidated, block level data storage. It does not rely on a LAN or WAN.

VPN: virtual private network help users to access a private network remotely through a virtual point-to-point connection.

EPN:enterprise private network is a computer network built by a business to interconnect its various locations to share computer resources.

PAN:personal area network is the smallest and most basic network for data transmission among personal devices.


LAN and WAN are the most widely used computer networks in today’s world. Both of them have their own advantages and disadvantages. When you are confused about which network to set up, network distance is a good aspect to consider. Although LAN has many benefits, you still need to choose WAN when it comes to large areas networking.

Jan 23

Layer 2, 3, 4 Switching: What’s the Difference?

Network switches are always seen in data centers for data transmission. Many technical terms are used with the switches. Have you ever noticed that they are often described as Layer 2, Layer 3 or even Layer 4? What are the differences among these technologies? Which layer is better for deployment? Let’s explore the answers through this post.

What Does “Layer” Mean?

Switch is used for linking the network devices together and switching the data from one port to another based on information from the packets being transmitted. The information complies with the OSI (Open Systems Interconnection) seven-layer model to ensure product interoperability. OSI model is a conceptual model that characterizes and standardizes the communication functions of a telecommunication or computing system without regard to their underlying internal structure and technology. Therefore, switches working on different layers of OSI model are described as Lay 2, Layer 3 or Layer 4 switches.

OSI model

Switch Layers
Layer 2 Switching

Layer 2 is also known as the data link layer. It is the second layer of OSI model. This layer transfers data between adjacent network nodes in a WAN or between nodes on the same LAN segment. It is a way to transfer data between network entities and detect or correct errors happened in the physical layer. Layer 2 switching uses the local and permanent MAC (Media Access Control) address to send data around a local area on a switch.

layer 2 switching

Layer 3 Switching

Layer 3 is the network layer in the OSI model for computer networking. Layer 3 switches are the fast routers for Layer 3 forwarding in hardware. It provides the approach to transfer variable-length data sequences from a source to a destination host through one or more networks. Layer 3 switching uses the IP (Internet Protocol) address to send information between extensive networks. IP address shows the virtual address in the physical world which resembles the means that your mailing address tells a mail carrier how to find you.

layer 3 switching

Layer 4 Switching

As the middle layer of OSI model, Layer 4 is the transport layer. This layer provides several services including connection-oriented data stream support, reliability, flow control, and multiplexing. Layer 4 uses the protocol of TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) which include the port number information in the header to identify the application of the packet. It is especially useful for dealing with network traffic since many applications adopt designated ports.

layer 4 switching

Which Layer to Use?

As for small networks, Layer 2 switches might be a good option. However, most networks will combine the Lay 2 and Layer 3 switches. Layer 3 is more intelligent and provides all the functionality of Lay 2 networks. Therefore, Layer 2 switches are used to provide cheap and easy connectivity to workgroups and Layer 3 switches are used to enable departmental networks to be segmented and controlled with no loss of bandwidth. Likewise, Layer 4 switches contain all the features of Layer 3 switch and some additional functions. Layer 4 switches are the enhanced version to provide higher class of service for controlling the network traffic.


With the development of technologies, the intelligence of switches are continuously progressing on different layers of the network. The mix application of different layer switches is a more cost-effective solution for big data centers. Understanding these switching layers can help you make better decisions.

Jan 16

Basic Knowledge of Wireless Access Point

With the rapid development of Ethernet network, cables are widely adopted for wired network connectivity. However, this may also lead to the problem of cable mess when large quantities of cables are deployed. In order to solve this issue, wireless network is now accepted by most network users to reduce the employment of cables. Wireless access point is an important device for connecting the wired network with wireless network. This article will talk about the fundamental knowledge about wireless access point.

What Is Wireless Access Point?

Wireless access point (WAP) is also known as access point (AP). It is a hardware device used in a wireless local area network (WLAN) for data transmitting and receiving. An access point connects users to other users within the network and also serves as the point of interconnection between the WLAN and a fixed wire network. Basically, the working principle of wireless access point is to broadcast a wireless signal that computers can detect, then computers can link to the network without using any wires.

wireless access point

Categories of Wireless Access Point
Fat Access Point

According to different working modes, wireless access point can be divided into several categories. Fat access point is the standard type which is also named as autonomous access point. This device is independent to be separated from other network devices or fat access points. It can automatically manage the functions for wireless client devices, such as wireless authentication and encryption. It is enough to use the fat access point at home or small office.

fat AP

Thin Access Point

However, when wireless access point is required in large enterprise or college campus, fat access point is not an ideal solution. Thin access point, namely lightwave access point, may be a better choice with all the functions controlled in a central device, like a wireless switch or wireless LAN controller. Thus, all the settings can be configured automatically by central device in a remote location.

thin AP

Fit Access Point

Fit access point is the combination of both fat and thin access points. It provides the wireless encryption function and has a remote controller for management. Fit access point can also support the DHCP (dynamic host configuration protocol) relay to get IP address for the station.

Applications of Wireless Access Point

Wireless access point used indoors are comparatively smaller for easier installation and maintenance. Signals broadcast from indoor access points are stable and high-qualified. Wireless radiation is also weaker which makes the indoor device ideal for dense deployment.


As for the outdoor application, access points are more solid to survive the harsh environment. Network signals are more stable with a bigger coverage. Point to point and point to multi-point network connections are widely used for outdoor application to link the networks among different locations.

Are Wireless Router & Wireless Access Point the Same?

The answer is no. A router can be an access point but an access point can’t be a router. A router is able to provide WiFi access and has an Ethernet switch built in, while an access point is to connect the wired Ethernet LAN to WiFi devices.

wireless router and wireless access point


Nowadays, wireless network is everywhere around us saving a lot of troubles for managing cable mess. A wireless router is often enough for family use since the coverage is limited. However, if you need to build up wireless network in large areas, wireless access point is always necessary.

Nov 25

Trend of Cloud Computing in Data Center

In the past, traditional data centers were mainly established by hardware and physical servers. However, the data storage is limited to the physical restriction of space. Network expansion became a headache for IT managers. Gladly, virtualized data center with cloud computing service has emerged and continued to be the trend since 2003. More and more data center technicians adopt it as a cost-effective solution to achieve higher bandwidth performance. This post will help you to have a better understanding of cloud computing in data center.


What Is Cloud Computing?

Cloud computing service is not restricted to one data center. It may includes multiple data centers scattered around the world. Unlike the traditional data center architecture where the network users owned, maintained, and operated their own network infrastructure, server rooms, data servers, and applications, cloud data center is providing business applications online that are accessed from web browsers, while the software and data are stored on the servers or SAN devices. Thus, applications using cloud-based computing are running on servers instead of local laptop or desktop computer. There is no need for users to know the position of data center and no need for experts to operate or maintain the resources in the cloud. Knowing the way to connect to the resources is enough for the clients.

Advantages of Cloud Computing

Cloud computing brings many great changes for data center networking. Here lists some key benefits of cloud computing.

  • Flexibility – Cloud computing has the ability to update hardware and software quickly to adhere to customer demands and updates in technology.
  • Reliability – Many cloud providers replicate their server environments in multiply data centers around the globe, which accounts for business continuity and disaster recovery.
  • Scalability – Multiply resources load balance peak load capacity and utilization across multiply hardware platforms in different locations.
  • Location and hardware independence – Users can access application from a web browser connected anywhere on the internet.
  • Simple maintenance – Centralized applications are much easier to maintain than their distributed counter parts. All updates and changes are made in one centralized server instead of on each user’s computer.


Traditional & Cloud Data Centers Cost Comparison

Cost is always an important concern for data center building. One reason why cloud computing is so popular among data centers is because its cost is much lower than the same service provided by traditional data centers. Generally, the number of cost mainly depends on the size, location and application of a data center.

Traditional data center is more complicated by running a lot of different applications, but this has also increased the workloads and most applications are only used by few employees making it less cost-effective. 42 percent of the money is spent on hardware, software, disaster recovery arrangements, uninterrupted power supplies, and networking, and 58 percent for heating, air conditioning, property and sales taxes, and labor costs. While cloud data center is performing the service in a different way and saves the cost for servers, infrastructure, power and networking. Less money is wasted for extra maintenance and more for cloud computing, which greatly raises the working efficiency.

Is It Secure to Use Cloud Computing?

Data security is always essential to data centers. Centralization of sensitive data in cloud computing service improves security by removing data from the users’ computers. Cloud providers also have the staff resources to maintain all the latest security features to help protect data. Many large providers will safeguard data security in cloud computing by operating multiple data centers with data replicated across facilities.


Cloud computing service has greatly enhanced the high performance of data centers by reducing the need for maintenance and improving the ability of productivity. More data centers are turning into cloud-based these days. It is definitely an efficient way to provide quality data service with cloud technology.

Nov 02

Building MDU Network into Brownfield and Greenfield

Multi-dwelling unit (MDU), namely multi-family residential, are the structures of housing where there are more than one living unit per location. MDU classification of housing has been considered as an important growth opportunity for communication services providers according to the population density and economics of scale. Generally speaking, there are two applications for MDU FTTx network deployments as “greenfield” and “brownfield”. This post will introduce the basic information about MDU and its network building applications.

Three Types of MDUs

In North America, MDUs can be classified into three construction versions of high-rise MDU, mid-rise MDU and low-rise MDU. Here will explain them one by one.

High-Rise MDU

This type of MDU refers to the large multi-story building like condo or apartment with more than ten floors and 128 living units using the internal residential entry. High-rise MDU is typically designed as vertical living style and planned for cabling access to the different stories and sections of the building thereby making sure that the FTTP network functions efficiently and reliably over high levels.


Mid-Rise MDU

Mid-rise (medium-rise) MDU is the leased or owned condo or apartment with up to 10 stories including 12 to 128 living units using the internal residential entry. For new mid-rise MDU, its fiber deployment is similar to the high-rise buildings. However, many old mid-rise MDUs are built as walk-ups and without provisions for new cabling networks. It is a challenge for these mid-rise residential buildings to find space for structured cabling.


Low-Rise MDU

Low-rise MDU is usually known as condo, townhouse or apartment constructed in garden style or horizontal style. There is only up to 3 floors or stories and 12 living units inside the low-rise MDU with external residential entry. The difficulty level for cable deployment also depends on whether the building is newly constructed.


Brownfield and Greenfield Applications

As mentioned above, the oldness and newness of residential buildings will affect the difficulty degree of cable installations. These two types of architectures are also the basic applications for building MDU network. Greenfield means the newly-built housing communities consisting of many separate living units typically joined together in one or several buildings. However, brownfield refers to the MDU that already exists in a typical urban area.

In a Brownfield application, a service provider must deliver fiber into the customer’s premises quickly, efficiently and securely. The ability to connect fibers as they are needed for new subscribers is best served using a simple “plug and play” approach. Thus, the splice storage should provide a demarcation point, such as a fiber demarcation box, equipped with industry standard connectors.


As for greenfield application, a network operator could ideally place the fiber to every living unit during initial construction. Fiber from every unit may then be run back to central closet and spliced as required inside a closure. A box such as the fiber splice box is an optimal and low cost solution.


Fiber Connectivity Methods

In MDU network applications, service providers can use factory-terminated patch cords or fusion-spliced pigtails to connect fibers. Patch cords are efficient connectivity methods because no tools or splices are required in the field to make the termination. Their simple plug and play installation also minimizes the required skills for setting up the connection, which reduces installation time and labor costs.

Fusion-spliced pigtails can alleviate the issues of cable management for massive patch cords and cable waste for long patch cords. However, the fusion splice machine is expensive and specialized training is required. The fusion splicer also requires electrical power in places like MDU hallways where power outlets aren’t readily available.


The building of FTTx network in MDUs has become more and more popular around the world. Project installer should make proper connectivity plan according to different structures of MDUs. The complexity of deployment will also depends on whether the MDU is built in greenfield or brownfield. A successful network deployment in MDU is measured in many ways.

Sep 13

Are You Familiar With Optical Switch?

There are lots of fiber optical devices used for communication networks. And optical switch is the one transmitting light signals between different channels. If a light signal is propagated from one phone or computer to another, it may be required to move between different fiber paths. Under this condition, optical switch plays an important part as it can transfer the signal with a minimum loss of voice or data quality. With the growth of technologies, many new methods have been combined with optical switch to achieve higher speed performance. Today, let’s step into the world of optical switch and explore its secrets.

Types of Optical Switches

Basically, there are two types of optical switches – OEO (optical-electrical-optical) switch and OOO (optical-optical-optical) switch. Network management functions of operating a network are available today using an optical switch with an electronic-based switching matrix. OEO switch receives the optical signal and converts it into electrical signal. Then it switches the signal into a different port and converts it back to optical signal for the network. By using an electronic fabric, OEO switch accomplishes bandwidth grooming and overcomes the network impairments.


OOO switch or all-optical switch enables the managing and switching of optical signals without converting them into electronic signals. This is especially attractive to those carriers operating large offices where up to 80 percent of the traffic is expected to pass through the office on its way to locations around the globe. It receives the optical signal and switches it to a different port in the optical domain, then returns it back to the network as an optical signal.


Technologies Applied In Optical Switch
MEMS Switching

MEMS (micro electrical mechanical system) technology uses many moving mirrors to switch the signals by deflecting light waves from one port to another. There are two MEMS structures. One is called 2D MEMS mirror, and another is 3D MEMS mirror. 3D MEMS based optical switch is more widely used in the industry. Following figure shows the operation process of the MEMS switching.


Liquid Crystal Switching

Liquid crystal technology employs the polarization effects of light in liquid crystals for light switching. At first, the light is filtered through polarization beam splitter to be separated into two or more paths. Then the light is put through a liquid crystal where its polarization property may be changed. At last, the light comes into the polarization beam combiner to be steered into the output port. And the output port is decided by the new polarization property of light.


Bubble Based Switching

Bubble based switch can use air bubbles and micro trenches aligned vertically and horizontally to switch the light. When there is no need for switching, the light can pass through the trenches uninterrupted. This technology has the benefits of low cost and fast switching time.


Thermo-Optic Switching

Thermo-optic switch will send light down a wave guard. The light is then split into different wave guards. If a switching command is issued, one of the wave guard arms is heated and the light within the wave guard will change its optical path length. Then the light is recombined and the path lengths of the lights are measured. If the lengths are different then the beam will be switched into one output port. If they are the same, the beam will be switched into another port.



Optical switches can be applied to various applications. In high speed networks, switches for this function are usually used within optical cross-connects to handle large amount of traffic. Another application is for the protection switching. If a fiber fails, the switch allows the signal to be rerouted to another fiber before the problem occurs. Also, the OADM (optical add-drop multiplexer) will use some optical switches to convert signals from a DWDM stream allowing carriers to selectively remove some wavelengths from a signal.


Optical switch is an important device that transfers light signals into different channels. Based on the original OOO type and OEO type optical switches, many new technologies have been brought in, which ensures the high performance of optical switches. With growing demands for higher data bandwidth, the future of optical switch is bright.

Jul 20

Optical Transport Network (OTN) for High Speed Service

Nowadays, the SONET/SDH network is an universal network that combines with WDM (wavelength division multiplexing) technique to transmit multiple optical signals over a single fiber. In future networking, high speed transmission is no doubt the migration trend. Inspired by the SONET/SDH network, ITU-T (ITU Telecommunication Standardization Sector) has defined the optical transport network (OTN) to achieve a more cost-effective high speed network with the help of WDM technology.

Generally speaking, OTN is a network interface protocol put forward in ITU G.709. OTN adds OAM (operations, administration and maintenance) functionality to optical carriers. It allows network operators to converge networks through seamless transport of the numerous types of legacy protocols, while providing the flexibility required to support future client protocols. Unlike the previous SONET/SDH, OTN is a fully transparent network that provides support for optical networking on a WDM basis. Since multiple data frames have been wrapped together into a single entity in OTN, it is also known as the “digital wrapper”.

Working Principle of OTN

You may wonder how OTN works in practice. Actually, its working structure and format very resemble the SONET/SDH network. Six layers are included in the OTN network: OPU (optical payload unit), ODU (optical data unit), OTU (optical transport unit), OCh (optical channel), OMS (optical multiplex section) and OTS (optical transport section).

OPU, ODU and OTU are the three overhead areas of OTN frame. OPU is similar to the “path” layer of SONET/SDH, which provides information on the type of signal mapped into the payload and the mapping structure. ODU resembles the “line overhead” layer of SONET/SDH, which adds the optical path-level monitoring, alarm indication signals, automatic protection switching bytes and embedded data communications channels. OTU is like the “section overhead” in SONET/SDH, and it represents a physical optical port that adds performance monitoring and FEC (forward error correction). OCh is for the conversion of electrical signal to optical signal and modulates the DWDM wavelength carrier. OMS multiplexes several wavelengths in the section between OADMs (optical add drop multiplexer). OTS manages the fixed DWDM wavelengths between each of the in-line optical amplifier units.


Advantages of OTN

There are many advantages of OTN. Firstly, it separates the network against uncertain service by providing transparent native transport of signals encapsulating all client-management information. Secondly, it performs multiplexing for optimum capacity utilization which enhances network efficiency. Thirdly, it improves maintenance capability for signals transmitting through multi-operator networks by providing multi-layer performance monitoring.

Migration to High Speed OTN

With the fast evolution of networking, OTN standard is able to reach a higher speed service. Its multiplexing hierarchy allows any OTN switch and any WDM platform to electronically groom and switch lower-rate services within 10 Gbps, 40 Gbps, or even 100 Gbps wavelengths. This eliminates the need for external wavelength demultiplexing and manual interconnects. OTN network is definitely the best solution for future high speed networking over long distance. The picture below shows the OTN mapping diagram for high speed transmission.



Over the years, OTN has never stopped improving itself. Driven by the needs for high speed transmission, OTN combined with WDM is obviously a better choice in networking. It is a cost-effective way to build an optical transport network accommodating high throughput broadband services. I believe more and more people will employ this standard in their own network in the near future.

Jul 01

Introduction to Simplex, Half Duplex and Full Duplex

Simplex, half duplex and full duplex are three kinds of communication channels in telecommunications and computer networking. These communication channels provide pathways to convey information. A communication channel can be either a physical transmission medium or a logical connection over a multiplexed medium. The physical transmission medium refers to the material substance that can propagate energy waves, such as wires in data communication. And the logical connection usually refers to the circuit switched connection or packet-mode virtual circuit connection, such as a radio channel. Thanks to the help of communication channels, information can be transmitted without obstruction. A brief introduction about three communication channel types will be given in this article.

Three Types of Communication Channel
1) Simplex

A simplex communication channel only sends information in one direction. For example, a radio station usually sends signals to the audience but never receives signals from them, thus a radio station is a simplex channel. It is also common to use simplex channel in fiber optic communication. One strand is used for transmitting signals and the other is for receiving signals. But this might not be obvious because the pair of fiber strands are often combined to one cable. The good part of simplex mode is that its entire bandwidth can be used during the transmission.


2) Half duplex

In half duplex mode, data can be transmitted in both directions on a signal carrier except not at the same time. At a certain point, it is actually a simplex channel whose transmission direction can be switched. Walkie-talkie is a typical half duplex device. It has a “push-to-talk” button which can be used to turn on the transmitter but turn off the receiver. Therefore, once you push the button, you cannot hear the person you are talking to but your partner can hear you. An advantage of half-duplex is that the single track is cheaper than the double tracks.


3) Full duplex

A full duplex communication channel is able to transmit data in both directions on a signal carrier at the same time. It is constructed as a pair of simplex links that allows bidirectional simultaneous transmission. Take telephone as an example, people at both ends of a call can speak and be heard by each other at the same time because there are two communication paths between them. Thus, using the full duplex mode can greatly increase the efficiency of communication.


A simplex fiber optic cable has only one tight-buffered fiber inside cable jacket for one-way data transmission. The aramid yarn and protective jacket enable the cable to be connected and crimped to a mechanical connector. It can be used for both single-mode and multimode fiber optic cables. For instance, single-mode simplex fiber optic cable is suitable for networks that require data to be transmitted in one direction over long distance.

Different from simplex fiber optic cable, the duplex one has two fibers constructed in a zipcord style. It is often used for duplex communication between devices to transmit and receive signals simultaneously. The duplex fiber optic cable is required for all sorts of applications, such as workstations, fiber switches and servers, fiber modems and so on. And single-mode or multimode cable is also available with duplex cables.


The concept of communication channel is important for understanding the operation of networking. Simplex, half duplex and full duplex are three modes of communication channels. Each of them can be deployed for different applications. It is more cost-effective to choose the right fiber optic cable according to its channel mode.

May 20

What is FTTx Network?


Since the customers have demanded for a more intensive bandwidth, the telecommunication carriers must seek to offer a matured network convergence and enable the revolution of consumer media device interaction. Hence, the emergence of FTTx technology is significant for people all over the world. FTTx, also called as fiber to the x, is a collective term for any broadband network architecture using optical fiber to provide all or part of the local loop used for last mile telecommunications. With different network destinations, FTTx can be categorized into several terminologies, such as FTTH, FTTN, FTTC, FTTB, FTTP, etc. The following parts will introduce the above terms at length.


FTTx is commonly associated with residential FTTH (fiber to the home) services, and FTTH is certainly one of the fastest growing applications worldwide. In an FTTH deployment, optical cabling terminates at the boundary of the living space so as to reach the individual home and business office where families and officers can both utilize the network in an easier way.


In a FTTN (fiber to the node) deployment, the optical fiber terminates in a cabinet which may be as much as a few miles from the customer premises. And the final connection from street cabinet to customer premises usually uses copper. FTTN is often an interim step toward full FTTH and is typically used to deliver advanced triple-play telecommunications services.


In a FTTC (fiber to the curb) deployment, optical cabling usually terminates within 300 yards of the customer premises. Fiber cables are installed or utilized along the roadside from the central office to home or office. Using the FTTC technique, the last connection between the curb and home or office can use the coaxial cable. It replaces the old telephone service and enables the different communication services through a single line.


In a FTTB (fiber to the building) deployment, optical cabling terminates at the buildings. Unlike FTTH which runs the fiber inside the subscriber’s apartment unit, FTTB only reaches the apartment building’s electrical room. The signal is conveyed to the final distance using any non-optical means, including twisted pair, coaxial cable, wireless, or power line communication. FTTB applies the dedicated access, thus the client can conveniently enjoy the 24-hour high speed Internet by installing a network card on the computer.


FTTP (fiber to the premise) is a North American term used to include both FTTH and FTTB deployments. Optical fiber is used for an optical distribution network from the central office all the way to the premises occupied by the subscriber. Since the optical fiber cable can provide a higher bandwidth than copper cable over the last kilometer, operators usually use FTTP to provide voice, video and data services.

FTTx Network Applications

With its high bandwidth potential, FTTx has been closely coupled with triple play of voice, video and data services. And the world has now evolved beyond triple play to a converged multi-play services environment with a high bandwidth requirement. Applications like IPTV, VOIP, RF video, interactive online gaming, security, Internet web hosting, traditional Internet and even smart grid or smart home are widely used in FTTx network.


FTTx technology plays an important part in providing higher bandwidth for global networks. According to different network architectures, FTTx is divided into FTTH, FTTN, FTTC, FTTB, FTTP, etc. FS.COM provides FTTx solutions and tutorials for your project, please visit FS.COM for more information.