Before explaining what an OLT is, we first need to talk about what a PON (Passive Optical Network) is.
A PON is a network that uses optical fiber with optical splitters along the path to provide point-to-multipoint data transmission, that is, a beam of light exits one end, passes through a splitter, and splits into n paths, without requiring electrical power along the path—only at the transmitters at the ends (OLT and ONT/ONU):

What are the main advantages of a PON network?

As mentioned above, there is no need for active components along the path, which would consume electricity.
Other advantages include the fact that, since it is built with optical fiber, there is no risk of equipment burning out due to an electrical discharge passing through the cable; it supports high speeds; and it is not affected by electromagnetic interference, since it transmits light signals rather than electrical ones, and are therefore insulated; they experience less signal attenuation over distance—meaning they can reach farther than metallic cables—and they suffer less deterioration, offer greater safety, and have lower maintenance costs.

So, what exactly is an OLT?

The OLT is the brain of the entire PON network; it’s located at the internet service provider’s end. It controls and manages the PON network, determines the timing and upload bandwidth for each ONU, and sets the priority for each service.
In short, it is the OLT that defines the services, their bandwidth allocation, and the priority of each one at the ONUs, sending parameters such as the VLANs and their respective interfaces, whether the port will be “transparent” or “tagged,” etc.

The OLT can also send extra parameters to the ONUs, such as which ports will perform NAT, if the ONU will be PPPoE, DHCP, Bridge and etc… even Wireless parameters, however these extra parameters, outside the definition of the protocol, generally only work integration when the OLT and ONU are from the same manufacturer, since each one ended up doing it their own way.

What is an ONT (Optical Network Terminal) / ONU (Optical Network Unit)?

ONTs or ONUs are the devices at the far end of the PON network that receive commands from the OLT; they are typically located in the subscriber’s home (FTTH), in a building (FTTA), or at a business (FTTB).

There are several types of ONUs from different manufacturers, such as Huawei, Fiberhome, Datacom, Intelbras, Nokia, Zhone, DasZhone, Furukawa, and many others, and all are theoretically compatible with any OLT, provided that both use the same protocol.

Can a Huawei OLT send PPPoE configuration settings to a Fiberhome ONU?

Unfortunately, this is not possible. What it can send are parameters defined in the protocol, such as which VLANs the ONU will have and their respective interfaces.

Some OLT support this, but in the example between OLT Huawei and ONU Fiberhome it does not.

Can a Huawei, Fiberhome or Datacom OLT send extra parameters to ONUs from the same manufacturer, such as PPPoE login and password for the ONU to dial, SSID and wifi password?

Generally yes, each one ended up defining its structure to be able to send this type of extra information/configuration to the ONU.

But how do I go about uploading PPPoE between different manufacturers?

One option would be, since VLAN parameters are included in the protocol standards, simply enable the ONU on the OLT as if it were in bridge mode, set the desired VLAN, and then manually add the extra parameters to the ONU (via the web interface, for example), such as the subscriber’s PPPoE settings, Wi-Fi configurations, and so on.
But of course, there are other ways to perform this type of configuration, such as via TR069, which our Made4Graph system also supports—because, imagine if for some reason the ONU resets; how will the PPPoE parameters be uploaded to it again? If the OLT doesn’t have this information (in this case), we’ll either need another protocol to send these parameters—in this case, TR069—or we’ll have to enter them manually through the ONU’s interface.

Which OLT manufacturer should I choose, and which one is the best?

There isn’t a “best” or “worst” option; it depends on your specific scenario and network.
Our recommendations are:

• Always use ONU/ONT and OLT devices from the same manufacturer. Some manufacturers tend to present more challenges than others, but in general, we recommend using as many ONT/ONU devices from the same manufacturer as the OLT as possible. This ensures full support and integration, and in the event of an issue requiring support, it prevents situations such as “We don’t support this ONU. “It’s the third-party ONU’s fault,” etc., even though there are standards governing this communication.
• Look for products approved by Anatel, this guarantees that at least the equipment has been tested.
• There are OLT manufacturers that block third-party ONUs and some even block specific versions or models, so it is interesting to have this information before purchasing OLT and ONUs.
• Check if it exists and how is the support of this OLT in Brazil, after all, when the “bug catches” we have to have a good support to help us.
• Check the equipment manufacturer’s documentation. Some manufacturers provide manuals, configuration examples, and/or usage guidelines; having all this information makes it much easier for the operations team or your IT/CGR/NOC to deploy the new equipment. Always look for equipment that comes with good documentation.
• Find out about the limits of this equipment and its boards, if the resources they have will meet your current and future needs, so you don’t have to change the equipment so soon.

But I will comment on my experience with some of the most well-known OLT manufacturers:

OLT Huawei

•  Excellent performance and stability
• They don’t have direct support here in Brazil yet, so the language can be a difficulty, but if you have a good supplier, he can help with support
• Excellent documentation
• Does not support 3rd party ONUs natively, however there are release to accept ways (Not recommended by manufacturer)

OLT Datacom

• Excellent and stable performance
• The support is excellent and made in Brazil
• Natively supports third-party ONUs
• Great documentation
• You can buy directly from Datacom

OLT Fiberhome

• Widely used by ISPs in Brazil
• Supports 3rd party ONUs on some firmwares
• It has support from Brazil
• Little documentation or difficult to find official information
• It works well if you use Fiberhome’s ONU

OLT VSolution
It is a simpler OLT with few PON ports, but it works well in smaller environments and networks

• There is no official support in Brazil
• Supports third-party ONUs
• Good option for simple scenarios
• Low cost

Doubts remain? Get in touch with us and we’ll help you as best we can 🙂

Zanclair Ferrari Junior | Network Consultant
JNCIS-SP | CCNA | HCIA | MTCRE