PON vs SFP ：What's the difference?-seesuo

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PON vs SFP ：What's the difference?

2023-11-07

PON vs SFP ：What's the difference?

PON (Passive Optical Network) and SFP (Small Form-factor Pluggable) are both integral components in optical networking but they serve distinct functions.

1.PON: PON is a network technology used in the provision of fiber-to-the-x (FTTx) broadband services, where x could represent the home (FTTH), building (FTTB), curb (FTTC), and so on. PON represents a point-to-multi-point, shared network infrastructure that uses passive (unpowered) optical splitters to split a single optical fiber to serve multiple end-users. It efficiently utilizes bandwidth and fibers, reduces costs, and facilitates easy network management. The two most popular PON standards are GPON (Gigabit Passive Optical Network) and EPON (Ethernet Passive Optical Network).

GPON SFP OLT transceivers are designed for theOLT side in the GPON network. GPON SFP uses a 1490nm continuous mode transmitter and 1310nm burst-mode receiver. The transmitter part utilizes 1490nm DFB LD with APC function and temperature compensation systems to assure a stable extinction ratio overall operating temperature range.

GPON OLT SFP transceiver is a high performance and cost-effective module for serial optical data transmission applications to 2.5Gpbs. GPON SFP transceiver is further divided into class B+ and Class C+

2. SFP: On the other hand, SFP is a compact, hot-swappable transceiver module used in networking equipment such as switches, routers, media converters, etc. It is used to connect a network device to a fiber optic or copper networking cable, converting electrical signals from the device to optical signals for transmission over the fiber and vice versa. SFP modules come in a variety of types based on communication standards, data rate, transmission distance, and the type of fiber used (single-mode or multi-mode).

PON vs SFP

In essence, the difference between PON and SFP lies in their roles within a network. While PON is a specific type of network structure that allows one optical fiber to serve multiple endpoints, SFP is a type of module that is plugged into a network device to connect it to the optical fiber network.

In certain scenarios, these two can be interconnected. For example, an SFP module that complies with GPON standard (called a GPON SFP) can be inserted into the PON port of a switch or router to connect a GPON network directly with the switch or router.

In terms of OLT modules, you will see various similarities between EPON SFP and GPON SFP like - type of laser, transmission distance and communication model, etc. However, the key difference among both of them is the sending power and receiver sensitivity.

The sending power of GPON SFP Class B+ is 1.5~dBm and its receiver sensitivity is -28dBm while the sending power of Class C+ is 3~7dBm and receiver sensitivity is -32dBm.

The sending power of GPON SFP the upstream bandwidth is scalable from 155Mbps to 2.5Gbps while the downstream is designed to deliver 1.25 Gbps or 2.5Gbps. At present time it is the most widely used consumer broadband service in the FTTH network. EPON SFP on the other hand supports symmetric bandwidth of 1.25Gbps in both upstream and downstream directions.

What do pon and sfp represent respectively?

What is pon ?

PON, or Passive Optical Network, is a type of fiber-optic network structure used primarily in telecom and broadband services. The primary mission of PON is to enable one single fiber to serve multiple homes, businesses, or endpoints.

Being “passive,” a PON network does not require any power for signal transmission, which significantly reduces the cost and complexity of the network setup. This is achieved using unpowered (passive) fiber optic splitters to distribute the signal to multiple end-users within the network.

A PON system consists of an Optical Line Terminal (OLT) at the service provider's central office and multiple Optical Network Units (ONUs) or Optical Network Terminals (ONTs) near end users. A single piece of fiber can be used to serve a point-to-multipoint (P2MP) network architecture.

Two widely used types of PON networks are GPON (Gigabit Passive Optical Network) and EPON (Ethernet Passive Optical Network), with GPON being the more common due to its ability to deliver variable length packets and higher capacity. PONs are typically used by Internet Service Providers (ISPs) to deliver broadband internet access and other services to homes and businesses.

How does a passive optical network work?

A PON system consists of an optical line terminal (OLT) at the communication company's central office and several optical network units (ONUs) near end users. Typically, up to 32 ONUs can be connected to a single OLT. The wordpassivesimply describes the fact that optical transmission has no power requirements or active electronic parts once the signal is being transmitted across the network. This is in contrast to active optical networks, which require electrically powered switching hardware to pass cells or frames across the fiber cabling.

This image shows how redundant OLT hardware commonly sits in the telecommunications service provider's central office. From there, fiber cabling is distributed up to 20 kilometers from the central office and is split into multiple ONUs using a passive optical splitter, which terminates the fiber connection close to the customer's demarcation point. The ONU will then deliver a network handoff using copper or fiber Ethernetcables, making it easy for customers to connect to their existing local area networks (LANs).

What are the different types of passive optical networks?

All PON systems have essentially the same theoretical capacity at the optical level. The limits on upstream and downstream bandwidthare set by the electrical overlay, which is the protocol used to allocate the capacity and manage the connection. The first PON systems that achieved significant commercial deployment had an electrical layer built on asynchronous transfer mode (ATM) or cell switching protocols and were called APON. These are still being used today, although the term broadband PON, or BPON, is now applied. APON or BPON systems typically have a downstream capacity of 155 megabits per second or 622 Mbps, with the latter being the most common. Upstream transmission is in the form of cell bursts at 155 Mbps.

Multiple users of a PON could be allocated portions of this bandwidth through the application of optical splitters and wavelength division multiplexingtechniques. A PON could also serve as a network trunk uplink between a larger system, such as a community antenna television system, and a neighborhood, building or home Ethernet network over coaxial cable.

The successor to ATM-based PONs are PONs that operate using Ethernet technologies. Gigabit PON (GPON), for example, offers a variety of speed options ranging from 622 Mbps symmetrical -- the same upstream and downstream capacity -- to asymmetric 2.5 gigabits per second download and 1.25 Gbps upload capacities. GPON is a hybrid system that uses ATM for voice transport and Ethernet for data transport. GPON is widely deployed in fiber-to-the-home networks.

A more recent Ethernet-based PON (EPON) is 10G-PON. This Ethernet-only technology delivers 10 Gbps download speeds with 2.5 Gbps upstream. Other EPON technologies, such as the International Telecommunication Union-Telecommunication Standardization Sector Next-Generation PON2 standard, are in the works and are expected to achieve up to 80 Gbps speeds in the future.

What are the benefits and limitations of PONs?

Benefits of PONs include the following:

They are cheaper to deploy compared to most alternative broadband delivery technologies.
They do not require electrically powered midspan devices to operate.
They use existing fiber optic
Their upgrade paths are plentiful, and throughput rates are keeping up with alternative technologies.
They are considered a secure broadband technology.
They can be transported over relatively long distances, such as 20 kilometers, on a central office loop.

The potential drawbacks of passive optical networks include the following:

They require an extensive fiber deployment.
Larger networks can become less efficient due to the amount of management traffic overhead being transported from the central office to individual customer ONUs.
Unlike active powered network technologies, PONs must adhere to strict transport distance limitations.

What is SFP?

SFP, standing for Small Form-factor Pluggable, is a type of compact, hot-pluggable optical transceiver used for both telecommunication and data communications applications. The term 'transceiver' means that the device can both transmit and receive data.

SFP modules are designed to plug into the SFP port of a network switch and enable the switch to communicate with the fiber optic or copper networking cable. Essentially, they convert the electrical signals from the switch into optical signals for transmission over the fiber and convert the optical signals back into electrical signals for the switch.

SFP modules support and are designed as per various communication standards, including Gigabit Ethernet, Fibre Channel, Synchronous Optical Networking (SONET), and others. They are versatile, supporting distances from very short reach in the case of copper SFP modules up to hundreds of kilometers for long-distance applications.

Moreover, there are several different types of SFPs available to cater to unique transmission distance, wavelength requirements, and the nature of the fiber. Some offer basic functionality, while others include diagnostic capabilities providing detailed visibility into the operation of the module.

One important characteristic about SFPs is that they are hot-pluggable, which means they can be plugged or unplugged without powering down the network system,providing a significant advantage in network management and efficiency.

Over time, as networks have evolved to require greater bandwidth, an enhanced version of SFP, known as SFP+ (SFP Plus), has been developed. This supports higher data rates, typically up to 10 Gigabits per second (Gbps), and is widely used in networks today.

Ultimately, SFPs and their evolutions have become a standard for high-speed, flexible, and scalable network connectivity in modern data and communications networks.

What are the types of PON fiber optical modules?

1. SFF/SFP/SFP+ and XFP fiber optical modules

According to different packaging types, PON fiber optical modules can be divided into SFF, SFP, SFP+ or XFP.

2. OLT fiber optical module and ONU fiber optical module

According to the different plug-in devices, PON fiber optical modules have two types，OLT fiber optical modules and ONU (optical network unit) fiber optical modules, both of which are encapsulated in SFP.

3. GPON fiber optical module and EPON fiber optical module

According to technical standards, PON fibr optical modules can be divided into GPON fiber optical modules and EPON fiber optical modules. GPON fiber optical module is a high-performance and economical fiber optical module used for 2.5Gpbs serial optical data communication applications. The advantage of this fiber optical module is that it can guarantee no damage to the eyes under any failure conditions. The EPON fiber optical module has SFP, XFP and SFP+ packaging forms, and its transmission distance can reach 20km, and the receiver part has a sealed preamplifier and a limiting amplifier with LVPECL compatible differential output.

What are the characteristics of PON fiber optical modules?

1. The working temperature is 0°C-70°C or -20°C-70°C;

2.1310/1490 burst mode transmitter and continuous mode receiver (ONU);

3.1490/1310 continuous mode transmitter and burst mode receiver (OLT);

4. The transmission distance can reach 20km;

5. The interface type is duplex SC or SC/APC;

6. It can avoid electromagnetic interference and thunder and lightning effects of external equipment;

7. Reduce the failure rate of lines and external equipment, improve system reliability, and reduce maintenance costs.

The difference between PON fiber optical module and traditional fiber optical module

1. The traditional fiber optical module optical signal transmission mode is point-to-point (P2P), and PON fiber optical module point-to-multipoint (P2MP).

2. Traditional fiber optical modules should be used in pairs and use one optical fiber or two optical fibers for transmission (duplex or simplex). PON fiber optical modules are not used.

3. The optical fiber link loss of traditional fiber optical modules includes attenuation, chromatic dispersion, fiber connection insertion loss, etc.. PON fiber optical modules have more frequency division ratio loss than traditional fiber optical modules.

4. The transmission distance of the traditional fiber optical module can reach up to 200km, while the PON fiber optical module is only 20km.

5. Traditional fiber optical modules are mainly used in backbone networks, and PON fiber optical modules are mainly used in access networks.

Conclusion

In this blog, we have shared brief information about PON transceivers, GPON SFP, EPON SFP, and their differences. PON technology because of its increasing demand and emphasis will keep on developing and applying to PON systems.

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