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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The basic requirement when selecting The ONUs then act methd the relevant information contained therein. It is allocated by the OLT, i. The GEM channels carry variable-length Ethernet frames.


This is called Ranging. The number of entries is given in the Plend field.

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 downstream transmission, i.

ONU management and control It is then transmitted in the downstream direction to the PON interface by using a scheduler.

GPON: VLANs and GEM Ports – Knowledge Base

The Port ID ranges from 0 to 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 downstream frame has a duration of microseconds and enfapsulation bytes long, which corresponds to the downstream data rate of 2.

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. Type 2 and Type 3: Each upstream transmission burst contains an upstream physical layer overhead PLOu section and one or more bandwidth allocation intervals associated with the individual Alloc-IDs.


Email will not be published required. This is shown in figure 2. For downstream trafficthe traffic multiplexing encapsulaation are centralized in OLT. The Port ID ranges from 0 to Figure 3 shows the GTC frame structures for downstream and upstream directions.

Each bandwidth type has its own Enccapsulation feature. Constant length frames facilitate QoS for time-sensitive applications.

Subscriber 3 in Figure 3 In the downstream direction, the OLT removes the outer tag or passes through the traffic to proper GEM port based on the tag methor and priority bits. It is allocated by OLT i. The BW map dictates the arrangement of the bursts within the frame and the allocation intervals within each burst. This T-CONT is of best-effort type and mainly used for data services such as Internet and services of low priority which do not require high bandwidth.

The Gpob Start and Stop field indicates the beginning and ending of upstream transmission window. 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.

Figure 4 shows a detailed methoc GTS frame format.

For example, Un-fragmented Ethernet frame as shown in the following illustration. It is a recipient of upstream bandwidth allocations within the ONU. If the ONU has no traffic to send, it transmits idle frames. The splitters are designated as [n: How to select a right optical fiber? The Plend is sent twice for redundancy. Both T-CONT are of guaranteed bandwidth types and mainly used for video services and data services of higher priorities. The ODN optical splitters divide the single fiber into multiple fibers going to different buildings and individual homes.


Each upstream frame contains a number of transmission bursts coming from one or more ONUs. A single fibre from the OLT runs to a passive Optical Splitter passive means, it does not require any power to operate which is located near the users’ locations.

Key Technologies of GPON:GEM

Figure 1 shows various FTTx network architectures. Each upstream frame contains a number of transmission bursts coming from one or more ONUs. In some existing CATV operator network or some telecom upgrading projects eg In the upstream direction, it is used to bear the service traffic. The OLT may allocate as much duration as it needs in the downstream, upto and including all of the downstream frame.

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. The downstream GTC frame provides the common time encapsulatkon for the PON and common control signaling for the upstream.

The V reference point represents the network-facing wncapsulation of the OLT.