Nokia’s 400G Everywhere, launched by Nokia in May last year, introduces the fifth generation of digital coherent optics for the transport network, enabling 400G Ethernet connectivity from the metro edge all the way to subsea communications. To learn how 400G Everywhere is transforming today’s IP-Optical networking, in particular, its role in optimizing today’s networks for a wide range of applications, Tara Neal from The Fast Mode spoke to Serge Melle, Director Product Marketing, IP-Optical Networks at Nokia.
Tara: Can you share on the evolution of the 400G transport network? What are the underlying technologies that we have today that enable this?
Serge MelleDirector Product Marketing, IP-Optical Networks at Nokia
Serge: The major driver for 400G Everywhere is the evolution towards new higher speed interfaces in routers. For about a decade, we had 100G Ethernet, being the standard high-speed interface. The introduction of 400 Gigabit Ethernet interfaces by IEEE and router vendors necessitated higher capacity in terms of throughput and bandwidth, driving the need for connectivity at 400 Gigabit speeds between routers. Since routers might need to connect across a few kilometres within a city, across a large metropolitan area, a region, the country, or even internationally, this is pushing optical technologies to support 400 Gigabits per wavelength over any distance.
Tara: What makes 400G Everywhere a significant concept for today’s transport networks?
Serge: For the transport network specifically, 400G Everywhere is significant in that it introduces a new generation of coherent optics technology that is capable of supporting not just 400 Gigabits per wavelength across any distance, but offering this capability cost-effectively.
Within the transport network, 400G Everywhere encompasses two parallel sets of technologies. In a metro area over short distances, there are pluggable coherent optics that can be equipped directly into a router that can operate at up to 400 Gigabits per wavelength across distances of 500 to 750 kilometres. That is extremely cost effective because the coherent optics can be deployed right in the router as opposed to provisioning a separate optical transport system.
While these pluggable coherent optics enable 400G Everywhere in metro and even regional applications, there are a separate set of coherent optical technologies that are optimized for very high performance. Those will enable the provisioning of 400 Gigabits per wavelength to connect routers over much longer distances, across thousands of kilometres. This leads to the fifth generation high performance coherent optics that can provide 400 Gigabits per wavelength connections over virtually any distance.
Nokia Office (Image credit: Nokia)
This essentially presents a two-prong approach to the implementation of 400 Gigabit Everywhere. The first is the provisioning of power-, space- and cost-optimized pluggable coherent optics in routers or transport equipment across access and metro networks. The second involves the deployment of high performance coherent optics for long haul applications.
Tara: Why would network operators deploy 400G coherent optics in routers?
Serge: Network operators are considering putting pluggable coherent optics in their routers, essentially, to reduce the cost of router-to-router connectivity in shorter distances across access and metro networks. In the previous generation of coherent interfaces, we had a router that connects the short reach optics to a transponder which features a coherent interface that can support speeds of 200 Gigabits to 400 Gigabits per wavelength. This however, involves the deployment of a separate box that comes with not just additional space and power requirements, but also the extra cost of optics needed to interconnect between the router and the transport equipment.
Tara: What are some of the key use cases and network applications for 400G Ethernet transport? Are IP-optical deployment options the same for all use cases and network applications, or are there different options best suited to different use cases?
Serge: There is definitely the need to optimize 400G Ethernet transport for the application. There are three most prevalent applications, and one of them involves connecting data centers to each other, across the metro. Typically, this would be hyperscalers or internet content providers with very large data centers that require connection across a campus or a large metropolitan area. This is a fairly simple application where all that is required is to connect two routers, over a point-to-point connection but at the same time, be able to support very high capacity. This is in fact one of the early applications for IP-optical integration that is being deployed.
Data centers supporting critical networks (Image credit: Nokia)
Another typical application will be service providers, whether they are traditional communication service providers, mobile network operators, or cable operators. What these players often have is networks in metropolitan areas that aggregate all of the edge traffic from their business customers, mobile traffic and residential broadband services. All of that capacity is aggregated into hub locations within their metros. Often times, the aggregation is conducted over a fiber optic ring, where 400 Gigabit Ethernet is delivered from routers at the edges of the network that aggregate their capacity to a hub location. This is essentially a good application for deploying 400G pluggable coherent optics in the routers, with a direct connection back to the hub.
The aggregated traffic is then transported over metro, regional or long-haul core networks that connect major network locations to each other, either across a metro or across a region - such as the northeast US or in the case of smaller countries like in Europe where the entire country is a region, or across a long-haul network i.e. connecting London to Frankfurt to Paris or New York to Chicago to San Francisco. Transport across these points requires routers with 400G connections to each other. However, often times the distances will be longer, requiring high performance coherent optics to connect the routers to each other, using a WDM transport system.
So to the question of whether there is a single solution for all of those network applications, the answer is no. For simple point-to-point connections, it is not necessary to have a very sophisticated optical transport layer. All that is required is the ability to combine 400G channels together on a fiber and carry them over a distance of 40, 80 or maybe a few hundred kilometres.
However, networks with metro aggregation rings, or metro or regional core networks involve more traffic and more locations, resulting in increased complexities. In these scenarios, it is much more efficient to connect the routers over a wavelength using reconfigurable optical add-drop multiplexers (ROADMs) that enable traffic to travel directly to the end router without having to navigate a host of intermediate routers along the way. This is essentially single-hop routing and it is a very efficient way to connect routers to each other directly, leveraging wavelengths over ROADM-enabled optical transport networks.
Tara: Why would network operators continue to use transponders in WDM systems for 400G transport?
Serge: There are two primary reasons why transponders continue to have a lot of value. First off, while IP networks are starting to use 400G interfaces, this requirement is not universal across all routers and locations. There will still be a lot of 100 Gigabit Ethernet ports on routers. In these cases, a transponder operates at a very high wavelength speed of 400 Gigabits, allowing more capacity over a wavelength while maintaining cost efficiency by deploying multiple 100 Gigabit Ethernet connections over that wavelength. In this application, operators essentially multiplex lower-speed router interfaces over a 400 Gigabit wavelength.
The other application for transponders is for long distance connections between routers at 400 Gigabits. This requires high performance coherent optics which are typically mounted in a transponder as it provides better tolerance for their heat and power dissipation. Transponders are therefore used to connect across distances of more than 500 kilometres up to thousands of kilometres, operating with fifth generation coherent optics at 400 Gigabits or more per wavelength.
Tara: Does the use of transponders apply for today’s greenfield deployments?
Serge: Yes, even in greenfield deployments, transponders are required for connectivity over long distances across regional and long-haul applications. Equally, there is also the opportunity to use the latest generation of 400G coherent optics in brownfield applications. For example, high performance coherent optics can be inserted into the unutilized wavelength positions across networks that are currently operating at 100 Gigabits or 200 Gigabits per wavelength but still have spectrum available on their fiber. By doing this, Nokia delivers a very unique value proposition with its fifth generation high performance coherent optics operating into the same wavelength plans as existing brownfield networks.
Tara: In deploying Nokia 400G Ethernet transport solutions what are some of the immediate benefits that network operators can expect to see?
Serge: First of all, by upgrading their IP networks and their routers to 400 Gigabit Ethernet interfaces, network operators are able to boost network capacity, at a lower cost per bit, as compared to using 100 Gigabit Ethernet. They are able to scale their IP networks cost efficiently, which is an important requirement for supporting the continuous growth in Internet traffic. The second major benefit is the optimization of coherent transport using pluggable coherent optics in the metro, and high performance coherent optics in long-haul networks. This enables them to provide 400G connections in their IP networks in the most cost-effective way, end-to-end for all the applications in their network.
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To learn more about Nokia’s 400G Everywhere, visit Nokia's 400G Everywhere Networks product portfolio. You can read more about 400G Everywhere in Serge's blog post Enabling 400G everywhere: comparing IP-optical network use cases or download a copy of Nokia's comprehensive 24-page E-Book on 400G Everywhere.
