ONT, OLT and MDU in GPON technology

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GPON of Huanetwork Wiki

• Gigabit Passive Optical Network
• A longer transmission reach, higher
  bandwidth, reliability,and lower operating
  expense (OPEX) on services.
• Longer transmission distance
• Higher bandwidth
• Better user experience on full services
• Higher resource usage with lower costs

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What is GPON PON is a point to multi-point
(P2MP) passive optical network, GPON stands for
Gigabit Passive Optical Networks. GPON is defined
by ITU-T Recommendation G.984.x. GPON can
transport not only Ethernet, but also ATM and TDM
(PSTN, ISDN, E1 and E3) traffic. GPON network
consists of mainly two active transmission
equipments, namely- Optical Line Termination
(OLT) and Optical Network Unit (ONU) or Optical
Network Termination (ONT). GPON supports
triple-play services, high-bandwidth, long reach
(up to 20km), etc.

• IFgpon GPON InterfaceSNI Service Node
  InterfaceUNI User to Network InterfaceCPE
  Customer Premises EquipmentThe optical line
  terminal (OLT) is an aggregation device located
  at the central office (CO) for terminating the
  PON protocol. Optical network units
  (ONUs)/Optical network terminal (ONTs) are
  located on the user side, providing various ports
  for connecting to user terminals. The OLT and
  ONUs are connected using an optical distribution
  network (ODN) for communication.The ODN is
  composed of passive optical components (POS),
  such as optical fibers, and one or more passive
  optical splitters. The ODN provides optical
  channels between the OLT and ONUs. It
  interconnects the OLT and ONUs and is highly
  reliable. The ODN network is passive, indicating
  that no optical amplifier or regenerator is
  deployed on the ODN network, thereby reducing
  maintenance costs of outdoor devices.

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GPON History Starting in 1995, work on
fiber to the home architectures was done by the
Full Service Access Network (FSAN) working group,
formed by major telecommunications service
providers and system vendors. The International
Telecommunications Union (ITU) did further work,
and standardized on two generations of PON. The
older ITU-T G.983 standard was based on
Asynchronous Transfer Mode (ATM), and has
therefore been referred to as APON (ATM PON).
Further improvements to the original APON
standardas well as the gradual falling out of
favor of ATM as a protocolled to the full, final
version of ITU-T G.983 being referred to more
often as broadband PON, or BPON. A typical
APON/BPON provides 622 megabits per second
(Mbit/s) (OC-12) of downstream bandwidth and 155
Mbit/s (OC-3) of upstream traffic, although the
standard accommodates higher rates. The
ITU-T G.984 Gigabit-capable Passive Optical
Networks (GPON) standard represented an increase,
compared to BPON, in both the total bandwidth and
bandwidth efficiency through the use of larger,
variable-length packets. Again, the standards
permit several choices of bit rate, but the
industry has converged on 2.488 gigabits per
second (Gbit/s) of downstream bandwidth, and
1.244 Gbit/s of upstream bandwidth. GPON
Encapsulation Method (GEM) allows very efficient
packaging of user traffic with frame
segmentation. By mid-2008, Verizon had
installed over 800,000 lines. British Telecom,
BSNL, Saudi Telecom Company, Etisalat, and ATT
were in advanced trials in Britain, India, Saudi
Arabia, the UAE, and the USA, respectively. GPON
networks have now been deployed in numerous
networks across the globe, and the trends
indicate higher growth in GPON than other PON
technologies like EPON. According to Huanetwork
estimation, 2014 global OLT ports shipment is 5.8
million, 2014 global ONT unit shipment is 48.5
million.
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GPON System Overview Introduction to the GPON
System Mainstream PON technologies include
Broadband passive optical network (BPON),
Ethernet passive optical network (EPON), and
Gigabit passive optical network (GPON). Adopting
the ATM encapsulation mode, BPON is mainly used
for carrying ATM services. With the obsolescence
of the ATM technology, BPON also drops out. EPON
is an Ethernet passive optical network
technology. GPON is a gigabit passive optical
network technology and is to date the most widely
used mainstream optical access technology.

• Why is GPON Required? As the wide use of
  broadband services and fiber-in and copper-out
  development, ISP(Internet Service Provider)
  requires a longer transmission reach, higher
  bandwidth, reliability, and lower operating
  expense (OPEX) on services. GPON supports the
  following functions to meet these requirements
• Longer transmission distance The transmission
  media of optical fibers covers up to 60 km
  coverage radius on the access layer, resolving
  transmission distance and bandwidth issues in
  twisted pair transmission.
• Higher bandwidth Each GPON port can support a
  maximum transmission rate of 2.5 Gbit/s in the
  downstream direction and 1.25 Gbit/s in the
  upstream direction, meeting the usage
  requirements of high-bandwidth services, such as
  high definition television (HDTV) and outside
  broadcast (OB).
• Better user experience on full services
  Flexible QoS measures support traffic control
  based on users and user services, implementing
  differentiated service provisioning for different
  users.
• Higher resource usage with lower costs GPON
  supports a split ratio up to 1128. A feeder
  fiber from the CO equipment room can be split to
  up to 128 drop fibers. This economizes on fiber
  resources and OM costs.

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• In the GPON network, the OLT is connected to the
  optical splitter through a single optical fiber,
  and the optical splitter is then connected to
  ONUs. Different wavelengths are adopted in the
  upstream and downstream directions for
  transmitting data. Specifically, wavelengths
  range from 1260 nm to 1360 nm in the upstream
  direction and from 1480 nm to 1500 nm in the
  downstream direction.
• The GPON adopts WDM to transmit data of
  different upstream/downstream wavelengths over
  the same ODN. Data is broadcast in the downstream
  direction and transmitted in the TDMA mode (based
  on timeslots) in the upstream direction.

• GPON Downstream TransmissionAll data is
  broadcast to all ONUs from the OLT. The ONUs then
  select and receive their respective data and
  discard the other data. Figure 5 shows the
  details.
• Main features
• Supports point-to-multipoint (P2MP) multicast
  transmission.
• Broadcasts the same data to all ONUs and
  differentiates ONU data by GEM port ID.
• Allows an ONU to receive the desired data by ONU
  ID.

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• T-CONT
• Transmission container (T-CONT) is a service
  carrier in the upstream direction in the GPON
  system. All GEM ports are mapped to T-CONTs. Then
  service streams are transmitted upstream by means
  of OLT's dynamic bandwidth allocation (DBA)
  scheduling. T-CONT is the basic control unit of
  the upstream service stream in the GPON system.
  Each T-CONT is identified by Alloc-ID. The
  Alloc-ID is allocated by the GPON port of the
  OLT, and the T-CONTs used by ONUs connected to
  the same GPON port of OLT cannot have the same
  Alloc-IDs.

• There are five types of T-CONT. T-CONT selection
  varies during the scheduling of different types
  of upstream service streams. Each T-CONT
  bandwidth type has its own quality of service
  (QoS) feature. QoS is mainly represented by the
  bandwidth guarantee, which can be classified into
  fixed, assured, non-assured, best-effort, and
  hybrid modes (corresponding to type 1 to type 5
  listed in Table 1).

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Table 1 T-CONT types
NOTEIn Table 1, X indicates the fixed bandwidth
value, Y indicates the assured bandwidth value, Z
indicates the maximum bandwidth value, and No
indicates not involved.
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GPON Networking Application GPON is a passive
optical transmission technology that applies in
FTTx solutions, including fiber to the building
(FTTB), fiber to the curb (FTTC), fiber to the
door (FTTD), fiber to the home (FTTH), fiber to
the mobile base station (FTTM), fiber to the
office (FTTO), and fiber to the WLAN (FTTW), for
voice, data, video, private line access, and base
station access services. Figure 7 shows FTTx
networking applications.
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The FTTx network applications in GPON access
have the following in common The data, voice,
and video signals of terminal users are sent to
ONUs, where the signals are converted into
Ethernet packets and then transmitted over
optical fibers to the OLT using the GPON uplink
ports on the ONUs. Then, the Ethernet packets are
forwarded to the upper-layer IP network using the
uplink port on the OLT.

• FTTB/FTTC The OLT is connected to ONUs in
  corridors (FTTB) or by the curb (FTTC) using an
  optical distribution network (ODN). The ONUs are
  then connected to user terminals using xDSL.
  FTTB/FTTC is applicable to densely-populated
  residential communities or office buildings. In
  this scenario, FTTB/FTTC provides services of
  certain bandwidth for common users.
• FTTO The OLT is connected to enterprise ONUs
  using an ODN network. The ONUs are connected to
  user terminals using FE, POTS, or Wi-Fi. QinQ
  VLAN encapsulation is implemented on the ONUs and
  the OLT. In this way, transparent and secure data
  channels can be set up between the enterprise
  private networks located at different places, and
  therefore the service data and BPDUs between the
  enterprise private networks can be transparently
  transmitted over the public network. FTTO is
  applicable to enterprise networks. In this
  scenario, FTTO implements TDM PBX, IP PBX, and
  private line service in the enterprise intranets.
  
• FTTD uses existing access media at user homes to
  resolve drop fiber issues in FTTH scenarios.

• FTTM The OLT is connected to ONUs using an ODN
  network. The ONUs are then connected to wireless
  base stations using E1. The OLT connects wireless
  base stations to the core IP bearer network using
  optical access technologies. This implementation
  mode is not only simpler than traditional SDH/ATM
  private line technologies, but also drives down
  the costs of base station backhaul. FTTM is
  applicable to reconstruction and capacity
  expansion of mobile bearer networks. In this
  scenario, FTTM converges the fixed network and
  the mobile network on the bearer plane.
• FTTW The OLT connects to ONUs using an ODN
  network, the ONUs connect to access points (APs)
  using GE for WLAN traffic backhaul. FTTW is the
  trend in Wi-Fi construction.
• FTTH The OLT connects to ONTs at user homes
  using an ODN network. FTTH is applicable to new
  apartments or villas in loose distribution. In
  this scenario, FTTH provides services of higher
  bandwidth for high-end users.

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• GPON Solution
• Provider Huanetwork Huanetwork is a independent
  GPON solution provider, working with over 500
  ISPs and carriers in the world. Huanetwork
  provides Huawei OLT at very competitive price,
  Huawei is the world leader in GPON market with
  36 marketshare. Full GPON solution (OLT, ODN,
  ONU) include technical support service are all
  available at Huanetwork, many ISPs starts their
  GPON journey by telnet accessing Huanetwork GPON
  LAB remotely, which is a free service provided by
  Huanetwork aiming at bridging the digital divide.
• welcome to Huanetwork GPON sepcial topic page
• Interested in GPON solution price, contact
  sales_at_huanetwork.comInterested in Huanetwork LAB
  test, contact support_at_huanetwork.com
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