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 Optical Splitter merely divides the optical power into N separate paths to encapsulatikn users. Downstream Traffic Management Figure 6 shows a sample model of downstream traffic management. The ODN optical splitters divide the single fiber into multiple fibers going to different buildings and individual homes. If the ONU has no traffic to send, it transmits idle frames. 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.

Figure 1 shows various FTTx network encapaulation. GFP allows direct encapsulation of variable length packets without repeating the encapsulation overhead on a regular basis.

Key Technologies of GPON:GEM

Link protection is also known as link aggregationwhich can protect the link and the same time, it can aggregate the traffic as well. The downstream GTC frame provides the common time reference for the PON and common control signaling for the upstream. It is allocated by the OLT, i. The downstream frame has a duration of microseconds and is bytes long, which corresponds to the downstream data rate of 2.

Each GEM port bears one kind of service traffic i. The OLT may allocate as much duration as it needs in the downstream, upto and including all of the downstream frame. In some existing CATV operator network or some telecom upgrading projects eg The GPON ODN, consisting of a single mode optical fiber and cable; the optical fiber ribbon cables, splices, optical connectors, passive optical splitters and ecnapsulation branching components are very passive.


In the upstream direction, it is used to bear the service traffic. It is allocated by OLT i.

Key Technologies of GPON:GEM | FTTH & Triple Play Broadband equipment

This is shown in figure 2. In the upstream direction, it is used to bear the service traffic. At the ONT, the traffic is classified again and placed into appropriate queues for each U interface. The splitters are designated as [n: GEM Frame Header detail. GEM can fragment its payload. The traffic bearing entities within the ONU are granted upstream transmission opportunity or bandwidth allocation by the OLT.

The Port ID ranges from 0 to 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 value and priority bits.

This is called Ranging. The Psync field indicates beginning kethod the frame to the ONUs. There are 2 types of GEM Channels: Encryption blocks are aligned to the GTC frame. PON system may be symmetrical or asymmetrical. In G-PON systems with the 1.

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. How to select a right optical fiber? The Port ID ranges from 0 to Email will not be published required. The CRC field provides error detection and correction on bandwidth allocation field. The downstream GTC frame provides the common time reference for the PON and the common control signaling for the upstream.


PON Core shell consists of two parts.

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. In case, any one fiber out of these encapsulatioj fibers is cut the ONU can be accessed through other fiber. The next section describes GPON key technologies.


The basic requirement when selecting 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. GEM supports fragmentation and reassembly.

The number of entries is given in the Plend field. Both T-CONT are of guaranteed bandwidth types and mainly used for video services and data services of higher priorities. The Slot Start and Stop field indicates the beginning and ending of upstream transmission window.

GPON Fundamentals – Knowledge Base

Type 2 and Type 3: The BW map dictates the arrangement of the bursts within the frame and the allocation intervals within each burst. It is allocated by the OLT i. The Plend is sent twice for redundancy. It appears as a single entity gpoh the purpose of upstream bandwidth assignment on the PON. Each upstream frame contains a number of transmission bursts coming from one or more ONUs.