Point-to-Point ensures next phase digitalization success

Submitted by fredrik.nyman on Thu, 09/19/2019 - 13:17

The use of a Point-to-Point in the fiber access infrastructure will ensure support for services in the next phase of the digitalization

There are two populare technology/architecture choices for fiber access infrastructure; Point-to-Point (P2P) or Passive Optical Networks (PON).  The debate about which choice that is better is often focused on CAPEX and OPEX and about how the operator can get the best return on investment. But there are also other aspects to consider, not least the fact that fiber network is now a vital social infrastructure for our communities as digitalization continues. More and more public services and functions are accessed over the network, and the digital economy is growing with businesses selling products and generating revenue based on the Internet. Everything from leisure to life-dependent medical services make use of the new infrastructure. This provides an additional and very important perspective on the P2P vs PON question. 

But lets first get the CAPEX/OPEX question off the table. Some claim that PON provides a lower initial investment, but it is also well-known that PON networks are operationally more challenging (more OPEX) and there are upgrade issues as bandwidth consumption grows which will add additional CAPEX investments before the technology is ultimately outdated. With a life-cycle perspective PON does not demonstrate any reasonable commercial advantage. From a technical perspective there is no question at all that P2P technology is better. P2P is always preferred as solution for business customers or where demanding applications are needed.

The Scandinavian countries were early out with fiber deployment. Today millions of ports have been installed and the penetration rates are sky high. The fiber infrastructure built over the past two decades has transformed the way the government, authorities, public functions as well as businesses and citizens go about their day-to-day business. An absolut majority of networks are built with P2P and it is therefore without a doubt that the business case for P2P as technology not only works but meet all technical and commercial requirements for a successful nation-wide (urban and rural) fiber deployment.

The service portfolio in these networks have covered the Business-to-Consumer market including Internet services in different speeds, but also a full triple-play palette of services (Internet, VoIP and IPTV). The P2P networks have been used with the Open Access business model creating fierce competition among service providers with different offerings but also in vertical business models where all services are provided by one party. Networks have also included a wide variety of Business-to-Business services including VPN, bistream/wholesale and other applications with demanding service level agreements. Today Internet of Things related services are growing fast and more and more Machine-to-Machine services are added to the networks.

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All in all the history of fiber deployment in the north of Europe has showed some real strong points for P2P;

  • Fiber deployment, the last mile access fiber plant is point-to-point anyway with one fiber connection per end-customer. Designing the fiber network architecture for P2P does not require any considerations about splitters and number of customers on a shared media and how to best prepare for a future when PON segments need to be further split and rebuilt as bandwidth consumption grows.
  • Regulatory compliance, Local-loop unbundling, often a regulatory requirement, can be easily satisfied to ensure equal access rights for service providers. Also requirements for redundancy and security as the importance of the infrastructure grows are easily satisfied with P2P.
  • Network Operation,
    • Ethernet - The P2P connection is a plain ethernet connection with symmetricla bitrate, not a shared media. P2P allows for a wider selection of services and the ability to upgrade individual customers
    • Rechability - modular optical components allow customization of individual customer links for distance (up to 80km) and type (single-fiber, dual fiber etc.), creating a lot more flexibility compared to PON where the segment split ratio has a direct impact on the optical dampening and distance to customers.
    • Working with the network - Ethernet is easy to maintain and troubleshoot and there are plenty of tools in the market to use.
    • Network deployment - the deployment of a P2P access switch with customer CPEs are simple to configure and with an OSS tool is it even rather easy to have all configuration automated, while in PON with its shared media needs to identify the customer placed ONTs manually and involves more manual steps.
    • Interoperability - there is no vendor lock-in between central nodes and customer placed equipment and media converters, you have more vendors to choose from and more products to work with to reach the perfect solution for your network
    • Redundancy - Using standard protocols it is easy to design the network to be redundant further out than in a PON topology, allowing the network to be used for more mission critical services
    • Staff - It is easier to find staff with competence in Ethernet networking than someone with PON knowledge.
  • Services,
    • The fiber infrastructure becomes independent of what types of services and their characteristics.
    • The network equipment for a P2P access network is typically sophisticated to deploy services with, both when it comes individual service parameters and to setup multiple services
  • Future proof,
    • Upgradeability - it is easier to upgrade individual links and devices without forcing fork-lift upgrades of adjacent CPEs or entier OLT chassis as PON often requires. Backwards compability in P2P has been demonstrated in migration from 10->100->1000->10000 Mbit/s access port speeds and there are no compability issues expected moving beyond 10Gbit/s.
    • Upgrade path forward; Ethernet P2P offers a path up to 800Gbit/s and prices are coming down fast thanks to the applicability of the technology in all other areas such as datacenters and enterprise. This means that there is a clear upgrade path available for P2P already today well beyond the life expectancy of current networks. With PON there it seems its always a discussion about the next-generation PON (so it has been for the past 15 years) and the technology still does not offer a solution that streches beyond a 2025-horizon which presents a risk for substantial costs. FTTx network operators need to look at 10-15 year and beyond deployment cycles.

What happens next?

Exciting times are ahead. New types of services are emerging that will put additional requirements on the networks.

Services with tougher characteristics such as low latency, higher availability and improved security are now hot topics. As Internet of Things and more automation is adopted Machine-to-Machine services will complement already tough Business-to-Business and Business-to-Consumer services in the networks.

Some examples of areas where new requirements will added to the fiber infrastructure are;

  • 5G Tactile Internet
  • E-Healthcare
  • E-Commerce 4.0
  • IoT/IoE

5G Tactile Internet – In 5G networks the expectations for services include a mix of Business-to-Business, Businerss-to-Consumer and Machine-to-Machine services. 5G masts will be placed everywhere to provide sufficient coverage and will therefore require a dense fiber infrastructure. Synergies with FTTH infrastructure are obvious and as services and users move transparently between 5G and fixed networks so will the underlying requirements on the network to enable e.g the Tactile Internet.

Tactile Internet is the concept of a network that supports realtime interactive communication with tough requirements on low latency in combination with high availability and reliability.

Example of where Tactile Internet will be needed;

  • Industry
    • Robots
    • Automation
    • Realtime applications
  • Traffic redirection
  • Self driving cars
  • E-Healtcare
  • Virtual Reality
  • Augmented Reality
  • Advanced gaming

A P2P network architecture is better suited to meet the requirements of latency, reliability and availability. The shared media structure of a PON network automatically imposes delays where data to/from an ONT need to wait for its timeslot before it gets transmitted. It is also much more complex to create redundancy for the PON segments, so end-points in the communication behind ONTs may not have adequate availbility and reliability so support these upcoming needs.

E-Healthcare -  The high bandwidth of fiber enable new ways of providing welfare services and in healthcare there are abundant examples of where a reliable infrastructure can cut costs and enable better services that might allow caretakers to stay at home longer. Examples include everything from remote diagnostic, relative simple welfare monitoring to more advanced teleoperation and tele rehab through robots. We may soon see robotic assistance with mundane tasks for elderly, controlled from central A.I systems.

Availability and reliability of the network becomes extremely important and a pure P2P infrastructure have the benefit to provide just that while still offering a simple and efficient operation.

The more advanced healthcare services, such as teleoperation and interactions based on Tactile Internet can also be delay sensitive and bandwidth demanding and again a P2P benefit here compared with PON and its shared media concept.

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How to fulfill the requirements for the next generation of services

With the next generation of services in mind, the fiber access network need to be built for both operational excellence and technical capability.

To strengthen the operation capability and to ensure availability, reliability and security the regulators in some countries have already given the recommendations to prolong the fiber access links into secured and controlled nodes and avoid using street cabinets or other local nodes for passive or active equipment. This means that placement of either passive splitters or active switches in the field may be regulatory discouraged and force a fiber topology that is P2P in its architecture to fewer central locations. As a result some of the main cost benefits

argued for PON - the passive splitter node and savings in the fiber plant by reducing the number of links is no longer valid. When regulatory concerns force a P2P fiber backhaul to central locations, a P2P access technologi is the natural choice to maximize the flexibility, reliability, availability, latency and security of the network and stand ready to meet the coming demands on services.

A P2P fiber access connection, it seems, has no limitations!

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