GPON Fundamentals
GPON Fundamentals
Базовая схема
Это попытка осмысления технологии PON и всей теминологии
На схеме показано:
- V - интерфейс OLT (головы), который смотрит во внешнюю по отношенияю к GPON-сегменту
- U - интерфейс ONU/ONT, который смотрит в сторону сети абонента, Residental Gateway - это абонентский роутер, возможно что функции абонентского роутера выполняется ONU/OLT
- R/S - интерфейс ONU в сторону OLT (естественно через Optical Distribution Network (ODN)
- S/R - интерфейс OLT в сторону Optical Distribution Network (ODN) (очевидно что
Интерфейсы S/R and R/S (и только они) поддерживают стек протоколов для работы GPON
T-CONT and GEM Ports
Definitions: T-CONT: A traffic bearing object within an ONU/ONT that represents a group of logical connections, and is treated as a single entity for the purpose of upstream bandwidth assignment on the PON. In the upstream direction, it is used to bear the service traffic. Each T-CONT corresponds to a service traffic of one bandwidth type. Each bandwidth type has its own QoS feature. ALLOC_ID: Each T-CONT is identified by the ALLOC_ID uniquely. The ALLOC_ID ranges from 0 to 4095. It is allocated by OLT i.e. a T-CONT can only be used by one ONU/ONT per PON interface on the OLT. GEM Port: A GPON Encapsulation Method (GEM) port is a virtual port for performing GEM encapsulation for transmitting frames between the OLT and the ONU/ONT. Each different traffic-class (TC) per UNI is assigned a different GEM Port. Each T-CONT consists of one or more GEM Ports. Each GEM port bears one kind of service traffic i.e. a T-CONT type. GEM Port ID: Each GEM Port is identified by a port ID uniquely. The Port ID ranges from 0 to 4095. It is allocated by the OLT i.e a GEM port can only be used by a single ONU/ONT per PON interface on the OLT. Figure 2 shows the relationship between T-CONT and GEM Ports.
