In North America, getting a decent Internet connection usually means comparing the two options (for 78% of Americans – see main article), which tend to be DSL from the local telco or cable Internet from the cable company. Providing an Internet connection over telephone lines or cable is a hack, as both were built to transmit specific types of information in analog form: point-to-point voice and broadcast video, respectively. The physical layout of the wires also reflects the use case: a star topology in the case of telephone, for communicating directly with the telco, and a ring topology in the case of cable, used to reduce the amount of wire, since all nodes were receiving the same information. Neither of these is ideal for an Internet connection, as the speed of DSL drops the further you are from the telco building and the bandwidth available to cable subscribers is necessarily shared with your neighbors. Other options exist, but are similarly limited. Broadband over power lines is not widely deployed and satellite broadband has high latency and degrades in adverse weather conditions.
Fiber-to-the-home is gradually replacing these other methods of providing consumer Internet connections. However, not all fiber services are created equal. Here are the main areas where fiber deployments differ (from each other and from cable/DSL), some that you would expect and some you might not:
Fiber connections have the potential to provide far more bandwidth than DSL or cable. When done right, fiber deployments can easily reach 1 Gbps, while DSL and cable are currently limited to approximately 200 Mbps per subscriber. Few ISPs in North America come close to these speeds, but they are important to keep in mind when considering the long-term viability of a particular type of infrastructure.
Access to the point of presence (POP)
A point of presence is a room or small building where cables from the surrounding area congregate. With cable and DSL, the POP is owned by the cable or telephone company and typically no other companies are granted access to the POP. Companies that resell DSL or cable service generally receive access only to the downstream Internet connection, once it has been converted from telephone lines or cable to some other medium, giving the resellers less control over the service than the telco or cable company.
Fiber deployments tend to provide POP access to any company that wishes to provide an Internet connection to subscribers that connect to the POP. This is called “open access”. Examples of open access fiber networks include Cleveland’s Case Western Reserve project, Amsterdam’s Citynet, and Google’s yet-to-be-deployed experimental network.
However, not all fiber deployments are open access. For example, America’s largest deployment of consumer fiber, Verizon’s FiOS, is not open access. Verizon controls the POPs and does not permit other companies to offer services over their fiber-optic cable. From a business perspective this makes sense, but it is far from ideal for consumers as they are stuck with Verizon’s fiber connection unless someone else deploys fiber to their house, which is unlikely and inefficient from an economic perspective.
PON vs. PTP
There are two main types of fiber architectures: passive optical networking (PON) and point-to-point (PTP). With PON, the fiber cables from a neighborhood are aggregated into a single fiber cable before continuing on to the POP. With PTP, each fiber cable goes directly to the POP.
While slightly more expensive to deploy, PTP has many advantages over PON. PTP offers faster speeds thanks to dedicated bandwidth for each user. PTP also allows each user to pick their own ISP (assuming an open access POP), while PON effectively forces all users on a particular aggregated cable to use the same ISP.
Unsurprisingly, Verizon picked PON for its FiOS deployment, as it is cheaper and they don’t plan to utilize its full bandwidth capacity or provide other ISPs with access to their POPs. Other deployments, such as Amsterdam’s Citynet, use PTP because of its consumer benefits. For more details on PTP and PON, see Ars’ The Internet of tomorrow article.
Typically, consumer Internet connections have 5-20 milliseconds more round-trip latency than business and academic Internet connections. As an example, round-trip latency from a Verizon DSL connection to a business (or a Verizon FiOS connection), all in New York City, averages 23 milliseconds, while round-trip latency from that business connection to a local university is under 2 milliseconds. Round-trip latency from a Verizon FiOS connection to that same business (and to the local university) is about 7 milliseconds.
Providing direct access to the fiber-optic cable in the POP would allow ISPs to offer round-trip latency that is very close to the theoretical minimum (about 100 kilometers per millisecond), as they could control all aspects of the connection, without being impeded by the telcos’ or cable companies’ latency-adding infrastructure.
Currently, the primary consumer application affected by latency is multiplayer online games. However, other applications are emerging that will benefit significantly from low-latency connections. Video conferencing is just one example.
Terms of service
While the technical details of the infrastructure are important, an Internet connection is not very useful if you are contractually obligated to do very little with it. Many ISPs require that customers agree to an adhesion contract that specifies a list of onerous stipulations on the use of their Internet connection. For example, the Verizon Terms of Service state that customers “may not … use the Service to host any type of server.”
It is important that customers not be restricted from making legitimate uses of their Internet connection, such as sharing freely-licensed software and videos or running their own web or e-mail server. Less restrictive ISP contracts will encourage new applications, like distributed search engines and the Freedom Box that Eben Moglen proposed. With contracts that actively discourage running servers, many interesting new applications are killed during conception because the prospective inventor does not want the applications’ users to run afoul of their ISPs’ terms of service.
Though it’s not a component of fiber infrastructure, terms of service contracts are nonetheless important to discuss. Some companies deploying fiber will also act as an ISP, as Google seems poised to do (though it will also be allowing other ISPs to provide service in its POPs), so bringing up the terms of service issue is relevant.
Though current fiber deployments are improvements over DSL and cable, many of them do not realize the full potential of fiber, by choosing PON over PTP, restricting access to the POPs, or maintaining restrictive terms of service. Projects like Google’s fiber deployment can change all of that. By deploying PTP fiber infrastructure with open access POPs, customers will be free to move between ISPs, forcing owners of other infrastructure (telephone lines, cable, or other fiber) to improve their offerings or face losing market share.