With the recent change of Government in Australia, the NBN’s Fibre to the Home (FTTH) rollout is up for review. Australia’s discussion focuses on the ideal infrastructure mix to deliver fast broadband. Fibre to the Node (FTTN) has been suggested as an alternative.
FTTN uses copper technology (VDSL and ADSL) to complete network connections from a cabinet (node) to each home. It can achieve speeds of up to 50Mbps, in practice, those speeds are rarely reached.
Fibre to the Node – the NZ experience
This article is a study of the New Zealand experience for both FTTN as well as FTTH.
TrueNet uses volunteers internet connections to help test broadband, providing them with a “probe” to connect to their modem. The probe completes hourly tests and reports results back to TrueNet’s servers.
Measuring and reporting performance of ISPs from homes in New Zealand has had a significant impact on performance.
TrueNet is looking for volunteers to do similar measurements to compare with New Zealand results as well as provide a baseline for improved Australian performance. If you are connected to a major ISP in a state capital and wish to help, head along to the volunteer page “Get Involved”. Our probe also provides a “double reach” wifi for your use.
TrueNet has measured FTTN in New Zealand for 3 years, first with ADSL, and in 2013 with VDSL. Almost 50% of New Zealand customers are able to connect to FTTN due to the impact of cabinetisation from 2009 to 2011.
The NZ government is also building an NBN-like Fibre to the Home (FTTH) solution, called Ultra Fast Broadband (UFB) and TrueNet publishes monthly comparisons between FTTN and FTTH.
Chart 1: Median performance by Technology for 5 major ISPs
The speeds obtained on FTTN (VDSL) at an average 20Mb/s are a lot less than FTTH at 28 or 83 Mb/s for the 30 and 100 Mb/s services respectively. Compare these to ADSL at just 8Mb/s
The technology analysis in Chart 1 is based on tests for all 5 major fixed line ISPs in New Zealand, Telecom, Vodafone, Slingshot, Orcon and Snap.
FTTN and FTTH explained
In Australia, broadband over copper is provided using ADSL over copper pairs between the home and the exchange. This technology is shown in Diagram 1, where the exchange part (DSLAM) is directly connected to the modem in the home over a unique copper pair.Diagram 1: How almost all people are connected on ADSL
In New Zealand, Fibre to the Node is the most common broadband connection. This involves placing the DSLAM within a cabinet located at the roadside, and feeding the cabinet with a fibre from an exchange (not necessarily the original exchange). Diagram 2 demonstrates this method.Diagram 2: Fibre to the Node (FTTN)
Fibre to the Home is the method being used to provide fibre connections by NBN in Australia, and Crown Fibre Holdings (CFH) in Joint Ventures with four Local Fibre Companies (LFCs) in New Zealand.
Technically, this is usually provided as Passive Optical Network (PON). Diagram 3 shows FTTH, with the exchange equipment (GPON splitter) in the exchange connecting to the modem in the home (ONT) over a single optical fibre.Diagram 3: Fibre to the Home (FTTH)
TrueNet can separate out details by Cabinet and exchange for VDSL and ADSL, along with comparisons of Cable and Fibre.
Test Results for October 2013
VDSL is being referred to in many countries as Fibre to the Cabinet (Node) because it is often the only way VDSL is distributed. This is not a technical limitation, VDSL works just as well from an exchange. Regulators can influence where the technology is located.
In Europe and Australia VDSL is restricted on copper in various ways, in NZ both ADSL and VDSL are available from either the Exchange or the Cabinet.
Chart 1 shows the average speed of each technology, including the speeds achieved during the busy hour when speeds are expected to slow. The average is calculated by taking the median of each probe by hour and then taking the average of all medians.
Chart 2 shows the median speed from midnight to 8am when lack of congestion usually enables the maximum speed to be reached.
The blue bars are the speeds delivered using FTTN (Fibre to the Cabinet) for both VDSL and ADSL. As a result of cabinetisation, most copper lines in NZ are at similar distances from the exchange as those from a cabinet, hence the similar results. FTTN lines are slightly faster due to the shorter line lengths typically found on cabinet distributions.Chart 2 provides a simple comparison for the performance of technologies.
Fibre is a Lot Faster than VDSL
VDSL, while twice the speed of ADSL is not Fibre. The best average speed is just 22Mb/s from a Cabinet (or Node), while most 30Mb/s fibre consumers get 28Mb/s, and similarly most 100Mb/s fibre consumers get over 90Mb/s. Higher speeds than 100Mb/s are shortly to be launched in NZ.
Fibre to the node improves VDSL as well as ADSL performance significantly. Most customers that became connected to the cabinet doubled their speeds on ADSL and were able to opt for VDSL, potentially quadrupling their speeds. For Example, TrueNet’s own office connection changed from ADSL to VDSL with an improvement in performance from 11Mb/s to 26Mb/s due to a cabinet (DSLAM) being installed 900m away.
A forgotten positive impact of fibre to the node is that DSL connections on the route to a cabinet lose the interference from other connections in their cable which are moved to fibre on FTTN, consequently increasing their DSL speed by up to 50%.
The NZ Market Explained
Fibre connections are supplied by four Local Fibre Companies, Chorus (equivalent to the lines part of Telstra but separated from the old Telecom) and 3 smaller companies.
Cable is supplied by Vodafone in parts of Wellington and Christchurch, (was Telstra until their subsidiary was sold recently)
VDSL is sold wholesale by Chorus to all ISPs on an equivalent contract basis. ISPs are not apparently supplying VDSL over LLU. although they can.
ADSL is wholesaled by Chorus but is also supplied over LLU by some ISPs.
Chorus own all Cabinets (Nodes) in NZ, most of which are now active, ie they have a DSLAM installed that is ADSL and VDSL capable and almost all are fed by fibre i.e. fibre to the node.
Details on how we measure are available on our Technical page.
ADSL, VDSL, DSL – the standard broadband service provided over a telephone line from an exchange or a cabinet (FTTN), VDSL is a faster version than ADSL. They use similar technology and backhaul, so sometimes DSL is used when referring to both.
Capped Plans – the most common ADSL service, where you have a monthly plan having a GigaByte (GB) limit of usage each month before your speed is slowed or you must pay more.
Unlimited Plans – ADSL service where there is no monthly limit on the amount of data used. Specifications for this service include that it may be “Managed” and have “performance reductions applied during peak demand periods.”
Cable – Cable is offered by Telstra & Optus, and is available in a limited number of cities.
DNS – Domain Name Server. As the Internet is based on IP addresses, a DNS service translates domain names into the corresponding IP addresses.
DSLAM – the exchange or cabinet based equipment that your modem is connected to, over the pair of copper wires that are exclusively allocated to your premises.
Ethernet – The wiring used to connect computers to a network, typically an Ethernet cable is coloured (often blue), with small square connectors at each end.
ISPs – TrueNet has probes measuring almost 20 ISPs but only reports on those where there are 5 or more probes working during any particular month.
Latency – The time for a packet of data to be returned by a remote server to the probe when a “Ping” command is issued. TrueNet sets targets for maximum median latency that are known to be achievable.
Median – The Median is found for each probe and this is input to any analysis to calculate the average performance. This means that any result represents the “middle” performance measure applicable for that probe. Using median ensures that the result is more representative due to the often skewed nature of measurements by probe.
Speed – Throughput or the median peak connection speed achieved during our standard test downloading an image from our test servers. TrueNet normally reports speed as a comparison at low vs high demand times to show any capacity constraints evident in speed performance, often called the Time of Day analysis.
UFB Fibre (NZ) – Ultra Fast Broadband connections are the service offered by some ISPs over the Fibre to the Home (FTTH) network built by LFCs over government subsidised fibres. Services now being offered include 100Mbps and 30Mbps.
NBN Fibre (AUS) – “NBN co is a single entity rolling out fibre nationwide and then wholesaling it to ISP’s” from a good comparison here
FTTN: Fibre to the node is based on fibre-optic cables run to a cabinet serving a neighbourhood. It uses existing coaxial or twisted-pair infrastructure to provide connections from the cabinet to the home.
FTTH: Premises are connected using a gigabit passive optical network (GPON). A fibre cable, known as the “drop fibre”, goes from the premises to the street. The “drop fibre” cable joins a “local network” which links a number of premises to a splitter in the fibre distribution hub.
LFC – Local Fibre Company. These companies are rolling out FTTH connections subsidised by the government, but must sell services through ISPs.
Webpage Download – TrueNet maintains a Standard Test page which is used for measuring the time to download the entire page. This page is visible here, we use a copy located on our test servers for test downloads. The time to download excludes the time for a browser to generate the page on a screen, some are faster than others.