Gfast and FTTdp: delivering gigabit broadband faster
Gfast: What it is and what it does
- Gfast is an ultra-fast broadband access standard for local loops shorter than 500m, at up to 2 gigabits per second dedicated per customer, depending on loop length.
- The various ITU-T and IEEE industry definitions and BBF specifications are shown below
- Gfast delivers gigabit faster by extending fiber broadband over existing wiring
- Dynamic bandwidth brings upstream/upload speed comparable to downstream/download speed
- Gfast (106MHz) is certified and its expanding deployment is well publicized. Gfast (212MHz) Deployment has already begun with Interoperability and Certification during 2018/2019. The comparison is shown in the tables below:
Gfast Speed Table | Bandwidth Range | ||
| Distance | Single Line, 106 Profile | Bonded Lines, 106 Profile | |
Up to 100 m | 500 – 1000 Mbps | 1 – 2 Gbps | |
200 m | 300 – 500 Mbps | 600 – 1000 Mbps | |
300 m | 200 – 300 Mbps | 400 – 600 Mbps | |
500 m | 100 – 200 Mbps | 200 – 400 Mbps | |
500+ m | Up to 100 Mbps | Up to 200 Mbps | |
Gfast Speed Table | Bandwidth Range | ||
| Distance | Single Line, 212 Profile | Single Line, 212 Profile | Bonded Lines, 212 Profile |
Up to 100 m | 1 – 2 Gbps | 1 – 2 Gbps | 2 – 4 Gbps |
200 m | 300 – 500 Mbps | 600 – 1000 Mbps | 600 – 1000 Mbps |
300 m | 200 – 300 Mbps | 400 – 600 Mbps | 400 – 600 Mbps |
500 m | 100 – 200 Mbps | 200 – 400 Mbps | 200 – 400 Mbps |
500+ m | Up to 100 Mbps | Up to 200 Mbps | Up to 200 Mbps |
Deploys faster by extending fiber to existing wiring infrastructure
- Eliminates the need for new construction work in and to premises
- No customer disruption
- Self-installation applies in many locations
Brings ultrafast broadband to more users by lowering cost of deployment
- Minimizing infrastructure construction
- Civil works approval requirements minimized
- Reverse power feed provides lower cost power alternative
- No new fiber in the last segment
- The DPU consumes so little power that it can be sustained with a little bit of power from each house
- Negligible to each subscriber but a big saver to Service Providers
Gfast - what's next?
5-10Gbps Gfast
Although the current and emerging 106MHz and 212MHz technologies will service the vast majority of requirments for many years, this is not the end of the story. ITU-T have started a new project - G.mgfast (Multi-Gigabit FAST) - to address functionality beyond G.fast. Deployment is a number years away and will be driven by the demand at that time. Project objectives include:
- Profiles beyond 212 MHz (424 MHz and 848 MHz)
- Full-duplex operation (echo cancelled mode)
- Aggregate data rates of 5 and 10 Gbit/s over single twisted pair and coaxial cable
- Operation over low quality twisted pair and quad, high quality twisted pair and coaxial cable
Gfast deployment: several alternatives
- FTTdp: The distribution point units (DPU) is in a street cabinet where power is available
- FTTdp: On a building or street pole where power may or not be available for the DPU
Where no power is available Gfast supports reverse power feeds from a nearby
connected building - Gfast is not solely FTTdp. As Fiber to the Building (FTTB) in a multi-dwelling or multi-tenant location where existing wiring may be used without disruption
- The distinct advantage being: significantly higher bandwidth services with no disruption or need to enter residential premises - a benefit for all.
Gfast Testing and Certification
BBF Interoperability and Certification Program
The program consists of: Interoperability plugfests and Certification with 40+ Certified Interoperable products in the first year.
BBF Interoperability and Certification Program
The program consists of:
Interoperability plug-fests
- Provide an invaluable accelerator to product and service introduction
- Leverages vast experience and expertise
- Open sourcing greatly increases importance of interoperability
Certification
- Avoids extensive provider testing before purchase
- Significantly reduces costs and accelerates time to revenue for all stakeholders
- Creates a trusted industry standard for implementation and high customer satisfaction
Designation of Gfast Certification
The Certification Test plan for Gfast is specified in IR-337. Click here for details on the BBF Members contribution site.
Scope of the Certification testing
The vast majority of features defined in the ITU-T base specifications grouped into test cases for the following categories
- Stability
- Fast rate adaption, bit-swapping, seamless rate adaption, dying gasp
- Functionality / Control
- Performance counter verification, PSD masks and spectrum control
- Performance
- Bit-rate, vectoring, noise immunity (SHINE / REIN)
- With reference to the ITU-T specifications:
- PSD testing ensures a device will not negatively impact other systems, by violating the required mask defined in G.9700
- Testing conformance to G.fast transceiver functions, such as data transmission, seamless rate adaption, fast rate adaption, bit swap, re-transmission, TIGA, etc., as defined in G.9701
- Certification tests the control, status, and performance parameters used to configure and monitor G.fast lines (See also TR-355 Yang models) as defined in G.997
Timelines
2017: Certification program >10 companies: first 6 companies certified - June 2017.Interop and certitifcation testing is via the Forum’s approved Gfast test lab UNH-IOL. (https://www.iol.unh.edu/services/testing/)
Gfast: Why it's important
Gfast: What's the impact?
- Recommended way to get ultrafast broadband where it is impracticable to economically deliver fiber
- Creates new opportunities for communities who have not had the necessary broadband infrastructure to attract business investment
- Brings high speed networking and the digital community to new areas around the world – possibly 100s millions
- Meets the demands of delivering increasingly ubiquitous cloud-computing
- An important new tool in providers' strategy for ubiquitous fiber deployment
Impact is dependent of stakeholder/application
- Enables the opportunity to run services/applications at a residence or small offices that have normally been associated with a fiber-connected metro office
- Enables high-end consumer video and gaming experiences
Gfast Council
Gfast is the new gigabit broadband access technology that deploys faster by extending fiber to existing wiring infrastructure. The Gfast Council will inform the market through events, white papers, use cases and other resources.
“Consumers want ultrafast broadband speeds and they want them immediately. In many cases, Gfast offers service providers the best chance to meet this requirement,” said Broadband Forum CEO Robin Mersh. “The Council will be the center of expertise in Gfast and as such will work to show how Gfast fits into the bigger gigabit broadband picture covered by the Forum’s work.”
The Council will also promote the Gfast Certification program, which today announced the first certified, interoperable products, to help accelerate the availability of interoperable solutions and expedite timely integration with service providers’ networks.
“Gfast has become an essential tool for service providers,” said Michael Weissman, Chair of the Gfast Council. “The Gfast Council combines the collective intelligence of 150 members of the Broadband Forum to make the rollout of Gfast deployments faster and more successful.”
Gfast Videos
Gfast Council Resources
The Gfast Council has made a branding kit for the promotion of Gfast in the industry.
Click here to download the kit. Gfast logos may only be used in accordance with the Branding Guide included in the Kit.
ITU-T and ETSI Reference Specifications
Recommendation ITU-T G.9700: Power spectral density specification
G.9700 specifies power spectral density (PSD) mask requirements, tools to support reduction of the transmit PSD mask, parameters that determine spectral content, allowable transmit power and verification of transmit PSD. The initial specification defined 106 Mhz profiles. The most recent (Amendment 2 published June 2017) completes the work that defines 212Mhz profiles.
Recommendation ITU-T G.9701: Physical layer specification
G.9701 specifies a gigabit broadband access technology that exploits existing infrastructure of wire-pairs originally deployed for POTS services. Equipment can be deployed from fibre-fed distribution points (FTTdp) located very near the customer premises, or within buildings (FTTB). It supports asymmetric and symmetric transmission at a data rate up to 1 Gbit/s on twisted wire-pairs using spectrum up to 106 MHz and specifies far-end crosstalk (FEXT) cancellation between multiple wire-pairs and facilitates low power operation.
Recommendation ITU-T G.997.2: Physical layer management for G.fast transceivers
G.997.2 specifies the physical layer management for Fast Access to Subscriber Terminals (G.fast) transmission systems. It specifies managed objects for configuration, fault, status, inventory, and performance management.
ETSI TS 101 548 European Requirements for Reverse Powering of Remote Access, Terminals, Transmission and Multiplexing
G.fast has been defined by the ITU-T in the following original documents together with later additions and amendments. The Broadband Forum’s FTTdp specifications work in concert with those of the ITU-T and ETSI.
Broadband Forum Reference Specifications
The Broadband Forum’s FTTdp/Gfast specifications work in concert with those of the ITU-T and ETSI.
TR-301: Architecture and Requirements for Fiber to the Distribution Point
This Technical Report provides the architectural basis and technical requirements that are needed to deploy FTTdp within a TR-101 and/or TR-178 architecture. To this end a new node type, the DPU, is defined being typically positioned at the Distribution Point (DP), supports one or more high-speed copper drops into the customer premises and uses a gigabit (or faster) fiber link to backhaul user data to a High Order Node. A key aspect of the node type is the ability for it to be reverse powered from one or more copper drop pairs.
TR-355: YANG Modules for FTTdp Management
TR-355 defines YANG data models for the management interfaces to support FTTdp. These models enable interoperability for FTTdp management. These include common BBF YANG types, an interface object supporting xDSL and G.fast, and the ITU‑T standardized objects for start up of G.fast or VDSL, G.fast and VDSL2 configuration, status monitoring, performance management, testing & diagnostics, and Single-Ended Line Test (SELT) and Metallic Line Test (MELT) configuration and test results.
- ITU-T SG15 has welcomed the Broadband Forum’s first deliverables on the YANG modules for FTTdp management that facilitate deployment of the ITU-T standardized objects for management of copper access (G.hs, VDSL, G.fast, SELT and MELT). The Broadband Forum's move to the state-of-the-art YANG modeling addresses operators’ needs for interoperability of management protocols and for programmability of today’s evolving deployment of SDN/NFV.
TR-371: G.fast Vector of Profiles (VoP) Managed Object Structure
TR-371 includes configuration management, status and performance monitoring: thresholds, test/diagnostics and inventory
TR-285: Copper cable models, required for testing G.fast systems
TR-298 Issue 2: Management model for DSL line test
WT-374: Yang Models for Management of G.hn Systems in FTTdp Architecture
TR-400 Testing of Bonded, Multi-Pair G.fast Systems provides testing methodology of multiport G.fast systems which use multi-pair bonding protocol G.998.2 amendment 4
Broadband Forum IR-337: G.fast Certification Test Plan (available to members)
Broadband Forum OD-362: G.fast Certification Requirements and Rules (available to members)
Work in Progress: Persistent Management Agent Aggregator Management Model (WT-393) and amendments to existing work such as WT-355