Infinera “What is…” Videos

One of the topics that can be confusing when talking about optical transmission is bit rate vs. baud rate. Bit rate refers to the amount of data that can be transmitted between two devices per unit of time– usually per second. Baud rate is similar but refers to the number of symbols that can be transmitted in the same interval. Let me explain further. Bit rate and baud rate apply to any data transmission regardless of the medium. The data transmission could be over the air like a 5G wireless transmission between your smart phone and a cell site. It could be over a hybrid fiber coax network that connects your in-home cable modem to the internet. It could also include coherent optical transmission over a fiber optic network that connects an enterprise to a data center across town, across the country or even across oceans. When we began connecting computers, we needed a simple, cost-effective data transmission scheme. That scheme is binary transmission. In binary transmission we send a single bit of information at a time. In the case of binary transmission over fiber optics, we turn a laser on to indicate a “1” while turning it off to indicate a “0”. If we turn the laser on and off at a rate of 1 billion times per second, we achieve 1 giga-bit-per-second transmission. If we pulse the laser at 10 billion times per second, we achieve 10 gigabit-per-second. This is in fact the transmission bit rate. With a binary transmission scheme, this is also the baud rate. But are the bit rate and baud rate always the same? No. In fact, except for binary transmission, the bit rate and baud rate are never the same. So, what if we could not only turn the laser on and off but also change its amplitude or its phase? That’s exactly what we do with modern coherent optical transmission systems. With quadrature phase shift keying we put the laser in one of four states. By doing so we can send two bits of information per symbol – effectively doubling the bit rate. Modern 800 gigabit per second Coherent optical engines like Infinera’s ICE6 transmit up to 100 billion symbols per second and utilize sophisticated modulation schemes that enable up to 6 bits to be transmitted per symbol. They also use something called polarization which enables the engine to double its transmission capacity. When combined, we can achieve over 1 terabit-per-second raw transmission. However, a portion of this data is required for internal use – for things like framing, overhead and forward error correction and thus the usable bit rate between devices is 800 Gigabits per second. The symbol or baud rate in this case is 100 Giga-baud. So, there you have it. Bit rate refers to the number of bits transmitted between two devices per unit of time – usually expressed in bits per second. The baud or symbol rate refers to the number of symbols that can be sent in the same amount of time. Only in binary transmission schemes do we see the bit rate equal to the baud rate. With all other more sophisticated transmission schemes, the bit rate will always exceed the baud rate because each symbol carries more than one bit of information.

July 03, 2023

What is Bit Rate vs. Baud Rate?

400Gigabit coherent pluggables are creating a lot of excitement in the networking industry. However, these pluggables come in multiple varieties and capabilities including ZR, ZR+, and XR. It’s important to understand the differences amongst them including their relative advantages, and the applications where they have the best fit. Lets start with 400ZR, which was the original 400G pluggable with specifications defined by the OIF. 400ZR is targeted at point-to-point metro data center interconnect applications. Client services are limited to 400Gigabit Ethernet and distances, are limited to 80 to 120 kilometers. The transmit output power is also low, and these pluggables do not support deployment over ROADM networks. Recognizing the need for 400G pluggables that exceed 120km, the industry created higher performance 400G pluggables, and the 400Gig ZR+ name became an umbrella term for any pluggable that offers better than 400ZR performance. 400ZR+ pluggables may comply with the Open ROADM MSA, OpenZR+ MSA, or other specifications. 400ZR+ reach is typically in the 400 to 1,000km range, though longer distances have been demonstrated including 1,800 kilometers in a live field trial with Infinera’s ICE-X ZR+ pluggable. Additional 400ZR+ enhancements include a wider range of clients including OTN, and 100Gigabit Ethernet, configurable data rates, and higher transmit power enabling transport over ROADM networks. XR Optics provides another 400G pluggable option that delivers high performance transport over both ROADM networks, and DCI networks. In addition, XR Optics provides support for point-to-multi-point connectivity leveraging digital subcarrier technology which can revolutionize the network architecture, and deliver considerable cost savings. Additional XR Optics benefits include high transmit output power, a single fiber working option, multi-generational interoperability, and intelligent manageability to ease deployment in routers and 3rd party devices. Standards are driven by the Open XR Forum which is also driving standards for the intelligent, and host-independent management of coherent pluggables. XR Optics also include temperature hardened variants for deployment in harsh environments. So whatever your 400G pluggable needs I hope this explanation helps you choose the best option for your network application.

July 03, 2023

What is ZR, ZR+, and XR optics?

Compact Modular platforms are a new type of optical networking solution used by network operators to build fiber optics based telecommunications networks. These types of platforms have become increasingly popular for network operators because of a handful of benefits that they provide over traditional optical networking solutions. The first benefit is that compact modular platforms are built from the ground up with open architectures. This makes them easier to operationalize and easier to introduce into a network, and make facilitate multi-vendor interoperability, which reduces vendor lock in and gives network operators more choices in the solutions that they choose. The second reason is that the latest generation of products are built using a modular sled based architecture. This enables a single platform to be seamlessly and flexibly configured with a variety of different functions by simply sliding in the appropriate sled for the function that you want. The result is a single platform that can be used to address a wide range of network applications, which reduces operational hurdles for network operators to introduce new technologies and capabilities into their network. Now, while relatively new to the industry, compact modular platforms already comprised more than 15% of all solutions sold in this space, and they're projected to grow at more than three times the market rate and become more than 50% of all solutions sold within the next few years.

February 02, 2022

What is Compact Modular

Coherent optical transmission technology utilizes lasers to enable the transmission of large amounts of information over fiber optic cables. This technology has been commercially available for a bit more than 10 years. In that time, we have seen five distinct generations of technology – the first generation enabled 100 gigabits per second, and the latest or fifth generation enables transmission of up to 800 gigabits per second. That’s the equivalent of downloading about 20 to 30 high-definition movies every second. In addition to increasing the capacity per laser or wavelength, each new generation of this technology has also enabled a substantial increase in the total amount of information that can be transmitted over a single fiber optic cable. 800G technology also provides substantial savings to network operators - saving as much as 30 percent over fourth generation 600G technology and 60 percent over third generation 400G technology. So, how did this happen? 800G transmission is enabled by three key technological advances. First is the ability to send data or symbols at a faster rate. This is referred to as the baud rate. Second is improvements in advanced modulation techniques including probabilistic constellation shaping and Nyquist digital subcarriers that enable us to send more information with each symbol. Finally, advances in digital signal processing enable us to compensate and overcome transmission impairments found in ultra-high-speed signals like 800G.

January 20, 2022

What is 800G?

Data Center Interconnect or DCI refers to high speed connectivity to connect two or more data centers. But, to fully understand DCI one must first understand Data Centers. Data centers are the heart and the brains of the internet in our cloud connected world. Data centers host applications and store the data for the Internet and cloud-based services. Without data centers, we would not have instant and consistent access to the information and applications that we all enjoy and expect today - even as we travel to different destinations across the country or across continents. There are thousands of data centers around the world. A single city can have numerous data centers. In fact, the city in the world with the largest number of data centers is London with over 300. Now obviously Data centers need to be connected to end users through service provider networks – like Verizon, ATT, T-Mobile, Orange. But data centers also communicate and transfer large amounts of data amongst themselves. Think of Netflix. Netflix has numerous deployment locations around the world to serve local communities. When they release a new video – it is distributed across a myriad of data centers. This same process is also used for business services. Take Infinera as an example. We use cloud-based solutions for our email, file sharing and video conferencing. Our data is replicated and stored at multiple data center locations including in the countries or cities closest to our offices. DCI provides the high-speed inter-data-center connections necessary to rapidly transfer mass amounts of information to ensure content consistency across all locations. As you can imagine, DCI traffic is one of the fastest growing segments in our networks. In order to keep up, DCI utilizes the latest high speed optical transmission technologies such as coherent optical networking and Dense Wave Division Multiplexing - which are two topics that we address in other videos.

January 20, 2022

What is DCI or Data Center Interconnect?

Coherent optics is a specific type of laser technology used by service providers to transmit large amounts of information over fiber optic networks. Historically, lasers transmitted information by controlling just the power levels of the signal – high power to transmit a “1” and low power to transmit a “0.” This type of technology – called “direct detect” – is only good for transmitting information up to about 10 gigabits per second. This may seem like a lot but is not nearly enough to cope with the massive amounts of bandwidth required by today’s networks, which often measure in the 100s of terabits of capacity. To overcome the limitations of direct detect technology, the industry developed a technology called coherent optics that is capable of transmitting more information and transmitting over longer distances. Coherent optics technology transmits 1s and 0s by altering the phase of the optical signal rather than the power levels. And while coherent optics is a far more complex technology, it has enabled us to increase the amount of information each laser can transmit over fiber optics by 80 times – from 10 gigabits per second to 800 gigabits per second. And of course, this technology continues to evolve.

August 06, 2021

What is coherent optics?

XR optics is the industry’s first multipoint coherent optical technology. XR optics solves a significant challenge that has plagued the optical networking industry for a long time. Since the inception of optical networks, there has been a significant mismatch between actual traffic patterns and the technology used to transport that traffic. Network traffic patterns, particularly in metro networks, are overwhelmingly hub and spoke – where you have lots of endpoints generating traffic and a much smaller number of locations aggregating that traffic. Traditional optical transmission technology provides only point-to-point solutions – a laser on one end of the fiber and an identical laser on the other end. As a result – by having to bookend every laser – network operators are forced to buy way more lasers than they need and use electrical aggregation solutions – like routers and switches – to aggregate traffic from multiple fibers. XR optics is a technology that enables a single laser to simultaneously communicate with multiple lower-speed lasers. This enables network operators to use a single higher-speed laser at the aggregation locations and collect traffic from numerous end-user locations, cutting the number of lasers required in half and eliminating the need for electrical aggregation devices – routers and switches – at those locations. The result of XR optics is a more cost-effective and streamlined network that is easier to operate and scale.

August 06, 2021

What is XR optics?

DWDM or Dense wave division multiplexing is a complex term for a relatively straightforward concept. It is a technology that transmits optical signals across fiber optics cables using a single color of light also called a wavelength. Traditional optical transmission solutions emitted broad spectrum – or white – light. Using that technology each fiber optic cable could only support the transmissions from a single laser. With dense wave division multiplexing, the data transmitted by numerous lasers – each transmitting in a different color of light - can be aggregated and transported over a single fiber. With modern DWDM technology 80 or more different optical signals can be carried over a single fiber dramatically increasing the capacity of fiber optics networks.

August 06, 2021

What is DWDM?

Open optical networks are networks that comprised a number of individual components that can be purchased from a variety of different suppliers and managed seamlessly as a single network. With an open optical network, the network operator can choose from the best-in-class components when building their network. The two key parts of an optical network are the optical line system and the transponders. Historically, network operators would be forced to buy all their transponders from the same vendor that supplied their optical line system. With open optical networks, network operators can buy the optical line system from one vendor and the transponders separately from a number of different vendors, while also ensuring that all these devices work together seamlessly and the overall network remains easy to operate. Open optical networks give network operators the ability to more rapidly introduce the latest technologies into their networks, irrespective of which vendor develops them. This ultimately results in the ability to be more competitive and offer more differentiated services to the market.

August 06, 2021

What is an open optical network?

Fiber optic networks are built with thin strands of glass about the width of a human hair that is wrapped in a protective rubber cladding. Lasers are used to transmit information across those cables. These networks provide the foundation for the internet that connects the world and enable the applications and methods of communication we enjoy today, such as phone calls, video conferencing, streaming videos, and social media. Now, people can connect to the network using a variety of different methods – mobile, cable, DSL, or WiFi – which all use either radio or electrical signals to transmit information. But very quickly, all this data is carried to a point in the network where it is aggregated and converted to an optical signal. Fiber optic networks enable the transmission of vastly more information over far greater distances than any other technology. This includes transmission across metropolitan areas and entire continents and even across oceans. Since the inception of fiber optic networks, service providers have deployed more than 5 billion kilometers – that’s enough cable to wrap the earth more than 120,000 times. And you can expect that, as bandwidth requirements continue to go up, we’ll continue to see more and more fiber cables deployed…. including all the way to people’s houses.

August 06, 2021

What are fiber optic networks?