traffic by using GPON encapsulating method. (GEM). 2. GPON fundamentals. Active transmission equipment in GPON network consists only of Optical Line. FTTH GPON – Learn FTTH in simple and easy steps starting from basic to advanced GEM (GPON Encapsulation Method) supports both native TDM and Data. EPON and GPON are popular versions of passive optical networks (PONs) GPON also uses a generic encapsulation method to carry other.

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One of the basic requirements of an optical system is to provide components with sufficient capacity to extend the optical signal to the expected range. The upstream GTS frame contains multiple transmission bursts. It is the data transport scheme in the specified GPON transmission convergence layer. Type 2 and Type 3: In the upstream direction, it is used to bear the service traffic. The Psync field indicates beginning of the frame to the ONUs. The optical network terminal ONTwhich is connected to the OLT at uplink side for service network interface, has many user-network interface ports.

The Port ID ranges from 0 to There are three categories or classes of components, which are based on power and sensitivity.

The grant map is dynamically re-calculated every few milliseconds. The downstream transmission, i.

DBA allows upstream timeslots to shrink and grow based on the distribution of upstream traffic loads. It is allocated by OLT i. The OLT may allocate as much duration as it needs in the downstream, upto and including all of the downstream frame.

To break down the bandwidth hurdle of the access over twisted pair cables, it supports high-bandwidth transmission. From the Optical Splitter, a single mode SM fibre strand run to each user. In the upstream direction, it is used to bear the service traffic.


The optical paths can vary between 2 to GPON adopts two multiplexing mechanisms- a in downstream direction i. When an ONU has no information to send, upon receiving a grant from the OLT, it sends an idle cell upstream to indicate that its buffer is empty.

The ODN optical splitters divide the single fiber into multiple fibers going to different buildings and individual homes. It is then transmitted in the downstream direction to the PON interface by using a scheduler.

The physical layer overhead PLOu at the start of the ONU upstream burst contains the preamble which ensures proper physical layer operation of the burst-mode upstream link.

It has constant-size HEC-protected header. For downstream trafficthe traffic multiplexing functions are centralized in OLT. Both T-CONT are of guaranteed bandwidth types and mainly used for video services and data services of higher priorities.

DBA is a methodology that allows quick adoption of users’ bandwidth allocation based on current traffic requirements and it is especially good for dealing with bursty upstream traffic. GFP allows direct encapsulation of variable length packets without repeating the encapsulation overhead on a regular basis.

A scheduler is used to transmit frames to the U interface. This combination of the two; together makes the ONT the most cost effective solution to provide GPON services to local and single-family, small, and medium enterprises.

The bandwidth allocations to different Alloc-IDs are multiplexed in time enfapsulation specified by the OLT in the bandwidth maps transmitted downstream. The splitters are designated as [n: Figure 5 shows upstream GTC frame format. There are 2 variations on tag assignment at V interface in upstream direction – the traffic at V interface could be double-tagged or single-tagged.


GPON: VLANs and GEM Ports – Knowledge Base

ONU management and control GPON supports triple-play services, high-bandwidth, long reach upto 20kmetc. The ONUs then act upon the relevant information contained therein.

Each Ethernet is mapped to a single or multiple by fragmenting GEM frames. If the ONU has no traffic to send, it transmits idle frames. Each allocation interval is controlled by a specific allocation structure of the BW map. It is allocated by the OLT, i. The traffic bearing entities within the ONU are granted upstream transmission opportunity or bandwidth allocation by the OLT.

Key Technologies of GPON:GEM

A data frame transport scheme used in GPON systems that is connection-oriented and that supports fragmentation of the network administrator data frames into variable sized transmission fragments. The BW map dictates the arrangement of the bursts within the frame and the allocation intervals within each burst. At the ONT, the traffic is classified again and placed into appropriate queues for each U interface. The downstream GTC frame provides the common time reference for the PON and common control signaling for the upstream.

Downstream Traffic Management Figure 6 shows a sample model of downstream traffic management. Link protection is also known as link aggregationwhich can protect the link and the same encapsulqtion, it can aggregate the traffic as well.