How ONT works

What is an ONT

ONT stands for "Optical Network Terminal." It is a device used in fibre-optic communication networks to convert optical signals into electrical signals (and vice versa) to enable the delivery of high-speed internet, telephone, and television services to homes and businesses.

In a Fibre to the Premises (FTTP) or Fibre to the Home (FTTH) network, the optical fibre extends from the datacentre or local exchange all the way to the customer's premises. At the customer's end, the fibre terminates at the ONT. The ONT serves as the demarcation point between the service provider's fibre-optic network and the customer's internal network. It typically connects to the Optical Line Terminal (OLT) on the service provider's side through a single fibre or multiple fibres, depending on the network architecture.

The ONT has various ports to accommodate different services, such as Ethernet ports for internet connectivity, telephone ports for Voice over IP (VoIP) telephony, and sometimes coaxial cable ports for cable television services. It converts the optical signals transmitted through the fibre into electrical signals that can be utilised by the customer's devices, such as computers, phones, and TVs.

ONTs are usually installed inside the customer's premises. They play a crucial role in enabling the delivery of high-speed and reliable fibre-optic services directly to end-users' homes and businesses.

What forms can the ONT be?

Openreach

BT ONT Resource

Although smaller units are the more common installation, some may be enclosed in a larger white cover, which includes a battery backup.

CityFibre

Business ONTs occasionally terminate directly into business-grade equipment, distinguishing them from consumer units.

ONT spoofing?

An ONT (Optical Network Terminal) is typically protected by a unique serial number assigned to its network interface. The serial number serves as an identifier for the ONT within the service provider's network.

When an ONT is connected to the service provider's network, its serial number is registered on the provider's end. This registration allows the service provider to authorize and authenticate the ONT to access their network services. The serial number acts as a form of identification for the ONT, ensuring that only authorized devices can connect to the network and receive the services.

The serial number is specific to the hardware of the ONT and remains unchanged throughout its lifespan. This provides a level of security and control for the service provider to manage the devices connected to their network and prevent unauthorized access.

While some ONTs may also have other identification features, such as MAC addresses, the serial number is the primary method used to protect and authenticate the ONT on the service provider's network.

!! It's important to note that MAC address spoofing is generally considered a form of unauthorized access and can be a violation of the terms of service of network providers. In many jurisdictions, engaging in MAC address spoofing with the intention of unauthorized access to a network is illegal and may result in legal consequences.

But you said something about OLT?

OLT stands for "Optical Line Terminal." It is a device used in fibre-optic communication networks to aggregate and manage multiple Optical Network Terminals (ONTs) or Optical Network Units (ONUs) that serve individual customers or subscribers.

In a fibre-to-the-premises (FTTP) or fibre-to-the-home (FTTH) network, the OLT is located at the datacentre or local exchange. It acts as the main point of control for the entire network, where all the fibre connections from various customer premises converge. The OLT communicates with the ONTs or ONUs at the customer end, enabling the delivery of high-speed internet, telephone, and television services. It handles the traffic between the exchange and the individual customers, routing data packets to the appropriate ONTs or ONUs based on their destination.

The OLT is responsible for several essential functions, including:

1. Managing Bandwidth: The OLT allocates and manages bandwidth for each ONT or ONU, ensuring fair distribution of network resources among subscribers.
2. Traffic Control: It controls the flow of data between the exchange and the customer premises, optimizing network performance and reducing latency.
3. Security: The OLT enforces security measures to protect the network from unauthorized access and potential threats.
4. Service Provisioning: It allows the service provider to provision and configure services for individual subscribers, such as internet plans, phone lines, and television channels.

The OLT plays a crucial role in enabling the delivery of high-speed and reliable fibre-optic services to customers in FTTP or FTTH networks. It forms the backbone of the network and facilitates the efficient management and operation of the entire fibre-optic infrastructure.

So how does this all connect?

In a fibre-optic communication network, the connection between the ONT, OLT, headend, and splitters is part of the overall architecture that enables the delivery of high-speed internet, telephone, and television services. Let's go through the connection process step by step:

1. ONT (Optical Network Terminal): The ONT is installed at the customer's premises, such as a home or business. It acts as the interface between the fibre-optic network and the customer's internal network. The ONT converts optical signals from the service provider's fibre-optic cable into electrical signals that can be used by the customer's devices, such as computers, phones, and TVs. The ONT may also have multiple ports for different services, such as Ethernet ports for internet connectivity and telephone ports for VoIP (Voice over IP) telephony.

2. Fibre Connection: The fibre-optic cable, also known as the "drop cable," connects from the service provider's network to the ONT at the customer's premises. This fibre connection is responsible for carrying the high-speed data from the service provider to the customer.

3. Splitters: Splitters are passive optical devices used to divide the optical signal into multiple paths. They allow a single optical fibre to serve multiple customers or ONTs. Splitters are commonly used in Fibre to the Premises (FTTP) or Fibre to the Home (FTTH) networks to efficiently share the high-speed fibre connection among multiple users.

4. OLT (Optical Line Terminal): The OLT is located at the service provider's datacentre or exchange. It serves as the main point of aggregation and control for the entire fibre-optic network. The OLT communicates with multiple ONTs from different customer premises and manages the traffic flow between them. It also handles the allocation of bandwidth to each ONT and ensures the efficient use of network resources.

5. Headend: The headend is a critical facility in the service provider's network infrastructure. It acts as the central hub where different types of content, such as television channels, video-on-demand, and other multimedia services, are received and processed. The headend is responsible for encoding, decoding, and distributing content to the OLT, which then sends the data to the respective ONTs.

Here you can see a typical FTTC and FTTP/FTTH diagram (Openreach).

! OHP/OLT (Optical Line Terminal)

! LLU stands for Local Loop Unbundling, which is a regulatory process that allows multiple telecommunications providers to offer their services over the same physical infrastructure owned by the incumbent telecom operator.

I heard something about PON, what is that?

PON stands for "Passive Optical Network." It is a technology used in fibre-optic communication networks to provide high-speed internet, telephone, and television services to multiple customers or subscribers.

In a PON architecture, the network is "passive" because it doesn't require active electronic components (like repeaters) for signal distribution along the fibre. Instead, passive optical splitters are used to divide the optical signal into multiple paths, allowing one optical fibre to serve multiple customers.

PONs offer several advantages, including:

• Cost-effectiveness: PONs require less active equipment, reducing deployment and maintenance costs.
• High bandwidth: PONs can deliver high-speed internet and other services to multiple customers simultaneously.
• Scalability: PONs can be easily expanded to accommodate more users without significant infrastructure changes.
• Energy efficiency: Since they do not require active electronic components along the fibre, PONs consume less power.

PON technology is widely used in modern fibre-optic networks, such as Fibre to the Home (FTTH) and Fibre to the Building (FTTB), to provide fast and reliable broadband services to residential and business customers.

Will I be able to upgrade in the future from 1Gb

Most likely yes, an ONT can be upgraded from a 1Gbps (1 Gigabit per second) connection to a higher speed connection, depending on the capabilities of the ONT and the network infrastructure.

ONTs are designed to support various data transfer rates, and many modern ONTs are capable of handling higher speeds beyond 1Gbps. The upgrade process may involve a simple software update or a replacement of the ONT's hardware module to support the higher speed.

However, the ability to upgrade an ONT to a higher speed depends on several factors:

• Network Infrastructure: The underlying fibre-optic network should be capable of delivering higher speeds to the ONT. If the network supports higher speeds, the ONT can be upgraded accordingly.
• Service Provider's Offering: The service provider must offer higher-speed plans to customers. If the service provider provides plans with speeds greater than 1Gbps, the ONT can be upgraded to accommodate those speeds.
• Hardware Compatibility: Not all ONTs are compatible with higher speeds. Some older ONTs may have limitations on the maximum speed they can support. In such cases, upgrading the ONT may require replacing it with a newer model capable of handling higher speeds.
• Customer Subscription: The customer must subscribe to a higher-speed plan offered by the service provider. Upgrading the ONT without an associated higher-speed subscription may not provide any benefit to the customer.

If all the necessary conditions are met, an ONT can be upgraded to a higher speed, providing customers with faster and more reliable internet connectivity. However, it's essential to check with the service provider to understand the upgrade options available and any associated costs or requirements.

!!! Nevertheless, the physical optical fibre cable from the premise back to the Exchange does not require replacement.

The fact that the physical optical fibre cable from the premise back to the Exchange does not need replacing is a significant benefit for several reasons:

1. Cost-Effectiveness: Fibre optic cables are a critical component of a fibre-optic network, and they can be costly to install and maintain. The fact that the existing cable doesn't need to be replaced means that the service provider can save on the expense of laying new cables, which can be particularly advantageous in large-scale network deployments.

2. Minimal Disruptions: Replacing fibre optic cables can be a disruptive process, especially in built-up urban areas or densely populated regions. By not needing to replace the cable, there are fewer disruptions to the surrounding infrastructure and the community, leading to smoother operations and reduced inconvenience to customers.

3. Time Efficiency: Installing new fibre optic cables can be time-consuming, involving planning, excavation, and installation. Since the existing cable can remain in place, the overall network expansion or upgrade can be completed more quickly, allowing for faster deployment of improved services.

4. Retaining Network Quality: Optical fibre cables are designed to be highly durable and have a long lifespan. By not replacing the cable, the service provider can maintain the network's original quality, which ensures a reliable and consistent service for customers.

5. Environmental Impact: Reducing the need to replace fibre optic cables helps minimize the environmental impact associated with the production, disposal, and transportation of new materials.

Overall, the ability to retain the existing fibre optic cable without the need for replacement offers significant cost savings, faster deployment, and a more efficient network expansion process, while also maintaining network quality and minimizing disruptions to customers and the environment.