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Table of Contents
GPON
| Reference | pon.ppt | GPON Fundamental | GPON PPT(Chinese) |
Architecture
Mapping of Ethernet in GPON
GEM Format
PTI Type
Transmission convergence layer
Types of PONs
| APON | ATM PON |
| BPON | Broadband PON |
| GPON | Gigabit PON |
| EPON | Ethernet PON |
| GEPON | Gigabit Ethernet PON |
| CPON | CDMA PON |
| WPON | WDM PON |
GEM Related Definitions
T-CONT:
A traffic bearing object within an 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 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, and can only be used by one 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 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, and can only be used by a single ONT per PON interface on the OLT.
Terminology
| GEM | GPON Encapsulation Method | |
| ONU | Optical Network Unit | |
| ONT | Optical Network Terminal | Almost same with ONU but normally with large port count, like E1/GE |
| ODN | Optical Distribution Network | |
| OLT | Optical Line Terminal | |
| WDM | Wavelength Division Multiplex Module | |
| NE | Network Element | |
| SNI | Service Node Interface | |
| UNI | User Network Interface | |
| T-CONTS | Transmission Containers | |
| PLI | Payload Length Indicator | |
| Port-ID | traffic identifier | Identifies the target ONU |
| PTI | payload type indicator | |
| HEC | header error check | |
| GTC | transmission convergence | |
| PLOAM | Physical layer OAM Operations, Administrations and Maintenance | |
| OMCI | The ONU management and control interface | |
| NNI | network-to-network interface | An NNI circuit can be used for interconnection of signalling (e.g., SS7), Internet Protocol (IP) (e.g., MPLS) or ATM networks. |
| UNI | User Network Interface | a demarcation point between the responsibility of the service provider and the responsibility of the subscriber. |