What Is OLT?
OLT (Optical Line Terminal), PON network consists of three parts: OLT, ODN and ONU. OLT belongs to the business node side of the access network equipment, connected to the corresponding business node equipment through the SNI interface, to complete the access network service access.
In the application of PON technology, OLT equipment is an important local equipment, which realizes the functions of:
1. Connected with the front-end (convergence layer) switch with a network cable, converted into optical signals, and interconnected with the splitter at the user end with a single optical fiber.
2. It realizes the control, management, ranging and other functions of the ONU of the user-end equipment.
3. OLT equipment and ONU equipment, as well as optical and electrical equipment.
OLT connected to the local equipment, if the optical signal is too strong (sometimes because of the short distance optical signal loss is small) need to add an attenuator. OLT connected to the ONU, before the two connected to the splitter.
In order to meet different application scenarios, OLT cooperates with various types of ONUs to realize FTTC/FTTB, FTTH, FTTO, FTTM and D-CCAP multiple optical access networking applications.
The PON network carries services such as voice, Internet access, IPTV video and dedicated data lines.
OLT Access Diagram
OLT Composition
The OLT usually consists of the following components:
1. The control board (also known as the main control board or called super control unit) generally an OLT has a main backup 2 boards.
2. DC power supply board (from the switching power supply negative 48 volts to the power supply) is also generally the main backup 2 boards
3. Fan unit (the main equipment cooling and environmental monitoring, etc.)
4. Frame (or called business frame)
5. Uplink boards: GE optical interface board (including buckle board), optical transceiver integration module, generally a board is 2-way GE port (currently 10GE has been commercially available),.
Uplink boards through the transmission (OTN transmission connected to the BRAS (Broadband Remote Access Server) and other aggregation switches or directly connected to the BRAS and other equipment and SR equipment, if there is an IPTV service also need to access the corresponding BNG equipment, The uplink boards can reach 10-40KM depending on the optical modules (without transmission in between).
6. Downstream boards (also known as business boards or PON boards), the general OLT equipment has a multi-port PON board (such as a board with 8 PON ports), each port goes down through the splitter (no more than 1:64) connected to the ONT terminal.
Downstream boards transmission distance and attenuation have their limitations because of factors such as ranging between ONT and OLT. For example, 8-port GPON OLT interface board (including pluggable ClassB+ optical module) requires ODN attenuation within -28db, and 8-port GPON OLT interface board (including pluggable ClassC+ optical module) requires ODN transmission attenuation within -32db;
However, considering the later maintenance factors and other comprehensive reasons: it is required that the boards of ClassB+ optical modules in the initial project should be controlled within -25db, and the boards of ClassC+ optical modules should be controlled within -29db.
7, according to business needs OLT can also be inserted (can be mixed) TDM business version, Ethernet business version, 16-way E1 business version and other boards.
8. The new OLT equipment must consider the full configuration of power consumption (1400W or so) to calculate the size of the power line, the size of the open occupancy (occupying 2 groups, a master and a backup).
According to previous experience, the general selection of air 63A; wire diameter selection of 16mm ² multi-stranded copper wire (flame-retardant), ground selection of 16mm ² of yellow and green copper wire.
9. Pay attention to the OLT upstream occupied terminals to facilitate the opening of the time without problems, downstream occupied terminals and so on should be considered clearly.
The length of the pigtail should be measured (optical jumper is provided by the manufacturer, the power cord is provided by the manufacturer, but pay attention to the length). As well as optical patch fiber (OLT side is SC fiber optic connector (downstream) and LC fiber optic connector upstream) in the ODF side flange type.
OLT Installation Specifications
A. Unpacking and inspection of goods
Check whether the outer box shipping contract number is correct, check whether there is any damage to the package, whether there is any damage to the goods, and whether the goods list is consistent with the real thing.
B. Hardware Installation
Cabinet installation
The installation position is in accordance with the design documents, the vertical deviation of the cabinet is less than 3mm, and the surface of the whole cabinet is in the same plane.
The structural parts of the cabinet are correctly installed in accordance with the specifications, without falling off or being damaged, and the bolts are correctly fastened. The front door of the cabinet opens and closes smoothly, and there are no handprints or stains on the surface.
Equipment installation
Equipment installation is in accordance with the design documents, and the equipment must be correctly fixed in the cabinet.
The veneer is installed with moderate force against the guide rail to avoid damage to the veneer by touching with other parts, and the bolts must be tightened.
During the construction process will touch the veneer and cable operation, must wear electrostatic hand can.
C. Cable placement
All cables are aligned with the project design documents, to ensure that the cable is not damaged, placed reasonably, straight line, tied neatly. Power lines, ground lines, fiber optic cables are placed separately.
Inside the cabinet, the tying interval of wire buckle/fiber optic taping is no more than 25cm, and the tying interval of user cables is no more than 20cm, and the cables are fixed on the cabinet by tying boards and cable routing resources.
Fiber optic distribution
Cut off the excess part of the bandage, temporarily unused power cables, fiber optic well protected and correctly placed.
Fiber into the cabinet must be set of bellows, bellows should be tied to fix the length of the cabinet into the internal length of no more than 10cm.
Fiber optic curvature is generally greater than 4cm, fiber optic plug clean and undamaged, plugged correctly.
D. Power on the equipment
Use a multimeter to check whether the input voltage is normal, open the power switch to measure whether the output voltage is normal.
Check whether the fan is working properly, check whether the green light of the single board is 15 bright 1S days cycle flash.
E. Data Configuration
On-site or network management to configure, confirm that the software version is the latest version or the contract requirements version of the configuration is successful, save the configuration and the configuration of the device to print a script for inspection.
F. Labeling
Fiber, cable deployment is complete, you need to paste the label, the default withered paste in the distance from the connector 2cm, the label production in line with the operator’s company specifications require labeling after the label is pasted down or to the right, and to ensure that the text side of the label facing outward.
G. Quality Inspection
The site supervisor carries out self-inspection in accordance with CHECKLIST.
Supervisor, construction team jointly signed on the CHECKUIST on-site self-inspection results are responsible for the supervisor of the data configuration of the equipment to check, and save the script.
Confirmation of the completion of construction, the cabinet debris cleaned up, the equipment to take pictures, including: the overall machine diagram, local installation diagram cable layout diagram, labeling diagram, equipment SN number labeling diagram micro-signal will be closed cabinet door, to confirm that the construction of this time does not have an impact on the other equipment, leave the scene.
Scenario Deployment Of OLT Applications
When OLT is deployed, different access strategies should be selected according to different service types, customer needs (long-term goals) and regions.
1. Ordinary Internet Group Customer Scenario FTTO
2. Home customer scenario one FTTB+LAN
3. Home Customer Scenario I FTTH
4. WLAN customer scenario FTTB+LAN
5. FTTB rural construction scenario I
6. FTTB rural construction scenario II
Introduction To OLT Equipment From Major Manufacturers
1. Huawei MA5680T Series
SmartAX MA5680T/MA5683T/MA5608T devices are integrated GPON/EPON optical access products launched by Huawei Technologies Co. With ultra-high convergence switching capacity, 3.2T backplane capacity, 960G switching capacity, 512K MAC address capacity, and maximum support for 44 channels10 GE or 768 GE access.
SmartAX MA5680T
SmartAX MA5683T
SmartAX MA5608T
2. ZTE ZXA10 C300
Both ZXA10 and C300 is a high-capacity, high-density xPON aggregation and access platform that supports the access aggregation and management control of full services for next-generation networks, such as HSI, VoIP, TDM, IPTV, CATV, mobile 2G/3G, WiFi, etc., and provides carrier-grade QoS and security and reliability guarantees.
ZTE ZXA10 and C300 Comparision
3. Shanghai Bell 7360 ISAM FX
7360 ISAM FX series OLT is the third-generation OLT system with application enabling mechanism, its function is much stronger than the first-generation Internet access platform and the second-generation triple-play access platform system, which is the best choice for “triple-play” full-service access.
The 7360 ISAM FX series OLTs meet operators’ requirements for multi-service access, multiple FTTx deployment scenarios, and the convergence of multiple PON access technologies. 7360 ISAM FX series OLTs are capable of integrating multiple accesses (point-to-multipoint, point-to-point, and DSL), such as EPON, 10G EPON, GPON, 10G GPON, P2P, and VDSL2, on a single platform.
“The 7360 ISAM FX series is available in three models depending on capacity:
7360 ISAM FX-16, providing 16 service slots
7360 ISAM FX-8, providing 8 service slots
7360 ISAM FX-4, providing 4 service slots”
4. Fiberhome AN5516-01
Fiberhome AN5516 series of carrier-grade 10G platform PON LAN equipment, using the full front-plug board, front outlet design, provides high-density xPON port disk, supports GE/10GE/STM-1/E1 uplink interface, can realize GPON/EPON/10G PON/P2P mixing, continuous evolution, and effectively protect the investment of the network construction
By using of high-performance chips, green energy-saving, and improve the network reliability and reduce operation and maintenance costs.
“Fiberhome AN5516 series OLTs with the following features:
High-capacity, high-density carrier-grade multi-ten-thousand megabit platform, single frame supports 256 PON ports, switching capacity of 4.384G, backplane bandwidth of 14.08T
Provide 10G high-speed uplink boards: 1*10GE+ 4*GE, 2*10GE+ 2*GE, 6*GE (optical and electrical optional).
Support STM-1/E1 leased line uplink interface, support up to 16×16GE leased line downlink interface.
1:32/64/128 optical split ratio, support for long transmission distance, support for CLASS C+ optical module”
OLT Common Commands
display board 0 #View status information of all single boards
display board 0/1 #View the detailed information of the first single board
display version #View basic device information (device runtime)
display language #View the version of the device
display patch all #View the patch status of the device.
display mac-address all #View all mac addresses under the device.
display mac-address board 0/1 #View the mac address of the first board.
display mac-address port 0/1/0 #View the mac address under this port.
display pstn state 0/2 #View the state of voice subscribers on the second board.
display if-h248 all #View the status of port h248.
display if-h248 attribute all #View h248 interface attribute information.
display service-port port 0/1/0 ont 1 (0/1/0 is the frame/slot/port number and 1 is the ONU id) #View whether the service port is online or not/ vlan/configuration
# Check the status of the ONU
interface gpon 0/1 (0 is the frame number 1 is the board number)
display ont info 0 1 (0 is the port number 1 is the ONU id number)
# View OLT receiving ONU optical information
interface epon 0/1 (0 is frame number 1 is board number)
display ont optical-info 1 1 (0 is the port number 1 is the ONU id number)
View the status of all users on a particular board
display board 0/1 (0 is the frame number 1 is the board number)
View the optical power received by the ONU
interface gpon 0/1 #(0 is frame number 1 is board number)
display ont optical-info 0 1 # (0 is port number 1 is ONU id number)
by-desc #Find ONT based on description information
by-ip #Find ONT based on IP address
by-loid #Find ONT based on logical id.
by-mac #Find ONT by MAC address
by-password #Find ONT by password
by-sn #Find ONT by serial number
View uplink board traffic
interface giu 0/17
display port traffic 1
In Summary
In today’s MANs, LANs and FTTx networks, OLT devices with functions such as master control, network distribution scheduling, and ONU usage viewing play an increasingly important role. How to choose the right OLT equipment to maximize the network link to meet the construction at the same time, reduce investment and maintenance costs, which will become to the operator or network provider of one of the main considerations.
