Gigabit Passive Optical Networks (GPON) FAQs
The following FAQ was developed by the HTNG Fiber to the Room Workgroup to answer commonly asked questions regarding Gigabit Passive Optical Networks (GPON).
What are the Basic differences between a GPON platform and a traditional Gigabit copper network?
First, both GPON fiber network and traditional copper network provide Ethernet connectivity from the main data room to the Ethernet end-points spread-out across the hotel or resort. All of the same services and applications that are traditional copper network and be delivered over GPON network (e.g. IP video, RF video, IP Voice, Analog POTS Voice, Security, Wi-Fi).
Are there certain types of properties or construction styles that are more conducive to deploying a GPON?
Large hotel/resorts that require higher density of Ethernet ports (e.g. metro high-rise hotels) as well as hotel/resorts where distance between main data center and the Ethernet end-point connectivity (e.g. sprawling resort property). Owners and operators who desire to converge networks and services over the fiber (e.g. guest services, back office, security, Wi-Fi and even DAS). Construction that has unique cable installation restrictions (e.g. restricted or non-existing pathways, historical and older buildings, architectural challenges, coring expense). And properties where copper cabling longevity is compromised by high humidity, high salt, high corrosion and lightning. Buildings where Ethernet tolerances were not part of the original design. In general, GPON networks should be evaluated for any size or type of hotel. Distance, speed, construction needs (core drilling etc.), lack of pathways, lack of IT Space, electrical requirements are all advantages of GPON networks.
Since Fiber cabling takes up less space, will the amount of pathway construction in my Hotel be reduced?
Proper planning in new hotel construction will result in less pathway requirements. No matter what, fiber optics take up less space. Retrofits will vary - existing pathways can be reused or made smaller. Removing pathways may not be cost effective.
Am I restricted from deploying any converged applications over a GPON network?
IP video, RF video, IP Voice and Analog POTS Voice can be converged over GPON fiber network. Furthermore, any and all IP/Ethernet device or IP/Ethernet services can be supported.
How does GPON support Back of House, common areas, public space, etc. areas of my property?
All of these areas can utilize an ONT (with varying port counts) and GPON. Additionally, distances between IT/TELECOM closets become less of an issue, due to increased distances available for fiber optic cabling.
With a traditional copper or copper/active fiber network, the integrator provides documentation such as cabling as-builts, testing results, certifications, etc. What type of documentation should I expect to receive at the completion of a GPON deployment?
Documentation will typically be the same, however placement of ONTs instead of edge switches will vary based on deployment type.
Can you explain what an ONT does? How many ports do I have available per room using an ONT?
ONT is an optical-to-electrical media converter. It accepts the GPON transmission on the network side and presents the necessary service connections (e.g. RJ-45 Ethernet, RJ-11 POTS, F-connector RF video, WAPs, POE). There are ONTs that only provide 1-port of connectivity and there are ONTs that provide 24-ports of connectivity.
Are there any restrictions to ONT Placement?
ONTs can be positioned in a room inside wall (i.e. electrical box or mud-ring) similar to traditional network. ONTs can also be mounted under furniture, inside closet, within flush wall enclosure or in pull down zone box in hallway.
How many fiber strands should be allotted to each ONT?
One primary connection, and a second optional connection for future use. TIA-568 standard is to pull two fibers to the outlet.
Is there an advantage in using pre-terminated fiber verses field termination?
Pre-terminated cables are tested in the factory (and generally have a rigorous QA process), but field terminated cabling should always be tested. Pre-terminated cables come in a variety of standard and custom lengths. Costs vary by region, installer, and should be evaluated on an individual basis. Individually terminated cables, by definition, are subject to the capabilities of the installer and may vary in quality and consistency.
Is it recommended to use one ONT per room verses an ONT shared among two or more rooms?
The preferred method may be one ONT per room, depending on construction and guest needs (as well as the number of connected devices in each room), an ONT may be utilized for multiple rooms. Ideally, one ONT per room is recommended, because one ONT per room generally allows for future flexibility, ease of design, as well as reliability.
What type of fiber cabling do I use with GPON? Are there certain connectors that I am required to use?
Single mode fiber in all cases for GPON. Connectors are dependent on the devices you are connecting. SC/UPC/APC connectors are typical.
What is the form factor of the splitters? Can we save space over the installation of a traditional IDF?
Splitters come in various form factors and dimensions, and can vary widely based on the manufacturer. Power considerations are no longer an issue, leading to less space needed for backup power. Additionally, many splitter location option are available based on reduced power consumption needs.
We have historically understood that Fiber cabling is more difficult to install than copper; i.e., bend insensitivity, complex splicing methods, etc. Can you explain how the technology has changed over time to alleviate these types of issues?
Fiber optic cabling construction has advanced to the point that durability and construction match that of a copper cable (and has exceeded it in terms of bendability). Further, the longevity of a fiber topic cable surpasses that of a copper cable many times over. Termination methods have advanced significantly, creating a much easier process for termination and splicing.
Are there tools available to centrally manage or monitor the performance of the GPON once it is installed?
Third party and vendor specific management and monitoring tools are available, just like a traditional copper / switched network.
How are ONTs remotely managed from the NOC?
The GPON system (OLT and ONTs) is managed similarly to a traditional switched network, utilizing the manufacturer’s network management system platform. When properly managed, a single console could be used to manage an entire GPON network.
How does network monitoring change when GPON is deployed vs. standard switched architecture?
GPON has a robust toolkit for troubleshooting and performance monitoring. GPON systems have been utilized for years, including numerous carrier level deployments (100,000s of OLT/ONTs).
Are GPON ONTs less secure than a traditional switch located in a locked closet?
Generally speaking, GPON ONTs are more secure than Ethernet switch. The GPON ONTs are typically unmanaged devices that have no local user interface (check manufacturer specific details). The OLT, locked back at the main data center, provides the centralized intelligence, network policies and management to control the thin-client ONTs.
Is port security required for every deployment on every ONT?
ONT ports are disabled by default. The activation of an ONT port is initiated through the PON manager and controlled by the OLT back at the main data center. Network Access Control (NAC) and IEEE 802.1x mechanisms provide whole additional layer of security on ONT ports.
If port security is not enabled, can end users attach rogue devices to the network?
No. The activation of an ONT port is initiated through the PON manager and controlled by the OLT back at the main data center. Network Access Control (NAC) and IEEE 802.1x mechanisms provide whole additional layer of security on ONT ports.
How much total bandwidth does GPON offer downstream and upstream?
GPON offers a total of 2.5 Gbps in the downstream and 1.2 Gbps in the upstream. Each ONT sees all of the PON bandwidth, but the amount of bandwidth utilized by each ONT is provisioned by the system operator. ONTs can be provisioned up to 1 Gbps. This can be provisioned arbitrarily based on the ONT version and the manufacturer’s capabilities. Current technology of GPON satisfies 2.5/1.2 Gbps. Future versions will allow added bandwidth.
Can every room be provisioned for a Gigabit per second of bandwidth?
Yes. GPON system can be oversubscribed on a provisioned basis as long as the bandwidth profile is set to best effort.
How is bandwidth dynamically managed on a GPON system?
In the upstream, dynamic bandwidth allocation (DBA) is utilized to assign bandwidth as needed to ONTs. Status reporting algorithms allow a master controller to rapidly assign time slots in the upstream based on ONT bandwidth requests. In addition, P bits are utilized in both the downstream and upstream to prioritize traffic on the PON.
What does a split ratio mean and how do I select it?
A 32 way split is shared amongst 32 ONTs, while a 64 way split is shared amongst 64 ONTs. This may result in more devices utilizing the same shared 2.5/1.2 Gpbs bandwidth. Utilize your integrator to determine the optimal split ratio based on traffic engineering and expected usage.
How much oversubscription can be supported on a GPON system?
Typically, GPON deployments are done with 32-way or 64-way splits. For example, every ONT can be provisioned with a Gigabit, giving a 64-way split an oversubscription of 26 in the downstream and 64 in the upstream.
When guests do a speed test will the GPON speeds be consistent with Ookla server based results?
Traffic shaping functionality built in to GPON chipsets generally provide accurate OOKLA test results. Although GPON has the ability to do traffic shaping, a hotel may use a gateway to utilize traffic shaping.
How are symmetrical services supported over GPON (Symmetrical services are: transmit and receive rates are the same)?
It is possible, but you need to consult the integrator (or network design) for manufacturer capabilities.
Are VLANs supported on GPON?
Yes. GPON systems can be provisioned with single or double (QnQ) tagging.
Can a VLAN per room or multiple VLANs per room be supported over GPON?
VLANs are supported in the same ways that a traditional switched network supports VLANs.
Does GPON support different classes of service, such as prioritized service for voice or IPTV (QoS)?
GPON supports different classes of services in the same way that an Ethernet switch does.
Are there any redundancy enhancements or options available with GPON?
Yes, there are several. FSAN defined Type-B PON redundancy option is available which can provide fiber route diversity between the main data center OLT and the optical distribution network splitter (e.g. 2:32 splitter, 2:16 splitter). Back at the main data center OLT redundant fibers can be connected to difference GPON ports, service modules or geographically dispersed OLTs for ultimate high network availability.
Can ONTs provide POE?
Yes; a variety of ONTs exist that can provide various forms, levels or standards of POE.
How do you provide power to electronics in the guest rooms that require POE?
There are a variety of power options such as local ac, remote dc power plants, digital power etc.
Can existing copper wiring be used for power?
Yes, existing copper cabling may be utilized. Considerations may include your local regulations, power distribution solution capability details, existing cabling suitability and location needs.
How much power is needed for each guest room?
Power requirement (wattage) depends on the device(s) to be connected. In a typical guest room, an ONT may be the primary device powered, with it in turn powering edge devices (using POE or POE+ through the data ports). Therefore, the total power need will be the power for the ONT itself plus the power for the edge devices. Typical allowances may range from 30-40W on the low side to 60-75W on the high side. A number of available ONTs, with four data ports, will require about 15W for the ONT itself and support up to 60W of POE or POE+ devices via the data ports. Power supplies, wire sizes, etc. can be selected for the specific power need or for the full powering capability of the ONT (i.e., 75W). Future needs should be taken into account when this decision is made (for example, will additional edge devices be connected to the ONT and what power will they need?). Greater and/or future power needs may also be supported by including additional (or spare) conductor pairs in the composite or power cables to each location.
What are the main types of remote powering solutions and considerations?
Remote powering solutions typically fall into one of three categories: Low Voltage Direct Current (LVDC), High Voltage DC (HVDC) or Digital Electricity (DE). LVDC follows the guidelines of NEC Article 725 with power and voltage limited to 100W and 60VDC (97W and 57VDC, typical) on a conductor pair. This solution can be installed by the same telecom technician installing the ONT and fiber cables. With low voltage, conductor size will increase to support longer distances and higher power (wattage delivered). HVDC follows the guidelines of NEC Article 830 and is also limited to 100W per pair; typical voltages are +/-190VDC to ground or 380VDC conductor to conductor, with a down-converter at the far end to return to low voltage for the ONT. HVDC can extend distance on a given wire size compared to LVDC but may require a licensed electrician and conduit to be installed. DE uses pulsed high voltage DC with line sensing between pulses to detect faults and shut off power within milliseconds in the event a fault is detected, greatly reducing the power absorbed in the fault compared to traditional LVDC or HVDC solutions. Because DE has a greater ability to limit power absorbed into a fault than traditional HVDC, even when greater than 100W is supplied per conductor, it typically can be installed by a telecom technician and generally does not require conduit.
What are the cabling options and considerations for fiber to the room/remote powering?
Cabling to power and connect ONTs falls into two main categories – composite (one cable sheath containing the fiber and copper for optical and power connections) or separate (two separate cables placed side-by-side, one fiber and the other copper for power). Composite cables allow a single cable to be placed/handled for fast, easy installation and are available in several conductor sizes to support various distances. Separate cables may also be used by pulling two cables (one fiber, one copper) to each room, allowing a single fiber cable to be combined with several copper wire sizes to support a range of distances. Separate cables may also be used where an existing copper cable is repurposed to provide power and a second, fiber cable is pulled to add the ONT’s optical connection. Where existing cables are used, it is important to evaluate the wire size, distance, power (Watts), condition/suitability and “landing site” in the room to ensure the cable can meet the requirements of its new application.
What are the location options and considerations for the ONT power source?
ONTs can be powered either locally (usually in the guest room or near the ONT location) or remotely. In-room powering typically uses a wall-type AC/DC converter to provide the needed 48VDC to the ONT; where needed, a battery backup device can also be placed with the converter. Remote powering typically originates from a floor closet (Telecommunications Room (TR), Intermediate Distribution Frame (IDF)) serving one or several floors or a Main Distribution Frame central to the facility.
What are the power back-up options as well as considerations for each option?
Local (in-room) power typically uses a small battery backup device in each guest room for each ONT. Periodic replacement (2-3 year intervals) and guest-room access may be required to maintain this solution. Remote powered ONTs can be backed up using centralized, high-quality telco-style battery backup supplies in conjunction with generator backup units.
We are also considering deploying DAS at the property. Could we leverage the GPON platform to assist with a DAS deployment?
To be clear, the 3G/4G cell traffic running over a DAS does NOT travel internally across the GPON system (and not on the same fiber strand that GPON runs on). However, DAS and GPON system can utilize the same fiber distribution plant, bulk DC powering distribution plant, emergency power backup, bulk battery backup and fiber management. Transport to Small Cells can be done using the GPON system, as long as the base station is IP-over-Ethernet.
What do I need to know about Analog telephones verses IP Phones support over a GPON Network?
If supporting telephone services over a PON, the voice traffic will be VoIP for at least the PON part of the network. Typically an IP-PBX is used in the MDF but it is possible to use an existing non-IP-PBX. This requires another piece of equipment called a Voice Gateway to be installed between the traditional PBX and the OLT. Some ONTs have one or more POTS ports where a standard analog telephone handset can be plugged in. The ONT will convert the analog telephone signal to VoIP (usually SIP), and send it to the VoIP Server or Voice Gateway. There are advantages and disadvantages to using an analog phone.
The main advantage of using an analog handset is cost. An existing handset might be able to be used or a new analog handset can be used. There is a significant cost savings for an analog handset when compared to an IP Phone. One big disadvantage of using an analog handset is compatibility between the ATA (analog telephone adapter) on the ONT and VoIP Server or Voice Gateway. The manufacture of the ONT should work with the manufacture of the IP-PBX to ensure compatibility. Another disadvantage of an analog handset is the ability to light the Message Waiting Indicator (MWI). Most ONTs were originally designed for residential use and the method to light the MWI is different for most hotel phones. Typically a hotel phone must have a modification to support the FSK method for lighting the MWI.
What do I need to know about RFTV verses IPTV distribution over a GPON network?
All GPON systems support IPTV natively since this service is the one of the main reasons for a fiber infrastructure. With very little additional cost the fiber used to deploy GPON can alternatively be used to deploy RFTV.
IPTV may require encoding equipment at the head end; normally a result of the video provider used, the split ratio selected or the number of TV channels deployed. If the video provider used delivers MPEG4 or HEVC encoded video channels and the channel count is less than 150 channels it would be likely that no encoding at the headend is required.
RFTV requires equipment at the head end to change the Analog or QAM signal on the coax to a lightwave and boost it to a level that will be acceptable at the ONT. The ONT must have an optical chip to take that lightwave and convert it back to the RF signal and place it on a coax port. Adding RFTV to a PON complicates the design effort so care must be taken to make sure data, voice, and video will work correctly.
Recent commercial televisions designed for hospitality can be configured to support IPTV or RFTV, sometimes both. The experience on these televisions would be the same whether IPTV or RFTV is used on the GPON network. A lot of the time an IPTV solution is selected because of the more advanced capabilities available which can present the appearance of an IPTV solution being a lot more expensive than RFTV. The most important point being that if the desire is to use the existing RFTV solution i.e. Televisions and headend equipment it is compatible with GPON. In the future the television system can be changed and now the property has more choice because RFTV and IPTV can be considered because a GPON network has already been deployed.
Ultimately, you need to speak with your service provider to ensure compatibility and appropriate engineering.
What do I need to know about an ONT with integrated WAP verses external WAPs?
Some ONTs have an integrated Wireless Access Point. This is very convenient and saves a requirement for another piece of equipment to be installed and managed. There can be a cost savings with an integrated WAP in both CapEx and OpEx. However, there are several drawbacks to this approach:
Most, if not all ONT manufactures, do NOT have an enterprise type controller to manage the Wi-Fi. This might cause many hours of work to do typical functions like changing SSIDs, changing channel numbers and changing power levels.
When the next wireless wave occurs and a hardware change is required, the whole ONT will have to be replaced in order to upgrade. Since most ONTs are designed to last 15-30 years, the full benefit of going with a GPON solution is diminished.
What about DAS, video cameras or other fiber-friendly technologies?
All of these technologies can utilize the same all fiber infrastructure (including GPON), generally without bandwidth constraints.
I am interested in learning more about GPON. Do you have any resources that you can point me to?
HTNG has produced a GPON 101 Webinar and Fiber to the Room Best Practices. Both can be found on HTNG.org.