Principles of Services Reuse-GEM Port and T-CONT [OLT Technology] Highlighted

Hello, everyone!

Today I will share with you principles of services reuse-GEM Port and T-CONT.

Principle

GEM Port and T-CONT divide the PON network into virtual connections to realize service multiplexing. The principle is shown in figure 1.

Figure 1 Service multiplexing principle of GPON system

A GEM Port can carry one type of service or multiple types of services. After the GEM Port bears the service, it must be mapped to the T-CONT unit for uplink service scheduling. Each ONU supports multiple T-CONTs and can be configured for different service types.

One T-CONT can carry multiple GEM Ports or one GEM Port, depending on the user's specific configuration. T-CONT goes upstream to the OLT side and demodulates the GEM Port, and then demodulates the service payload in the GEM Port for related service processing.

Service Mapping

• Downstream direction

All services are encapsulated in GEM Port in the GPON service processing unit, and then broadcast to all ONUs under the GPON interface. The ONU then performs data filtering based on the GEM Port ID, and only retains the GEM Port belonging to the ONU and decapsulates it to send the service from the ONU's service interface to the user equipment as shown in figure 2. 

Figure 2 GPON service mapping relationship (downstream)

• Upstream direction

Various services are first mapped to different GEM Ports on the ONU, and the GEM Port carries services and then maps to different types of T-CONTs for upstream transmission to the OLT. T-CONT demodulates the GEM Port unit on the OLT side, sends it to the GPON MAC chip to demodulate the service in the GEM Port payload, and then sends it to the relevant service processing unit for processing. As shown in figure 3 (upper line).

Figure 3 GPON service mapping relationship (upstream)

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Thank you!