GPON Introductioncspace.userapp.com/cspace/CORTINA/1387333165303448005308.pdf · GPON Introduction Chengcheng Huang ... GPON vs. EPON ITEM GPON EPON OAM Mandatory eOAM/PLOAM/OMCI

© Cortina Systems, Inc. 2012 All Rights Reserved Proprietary and Confidential

October 12, 2013

GPON Introduction

Chengcheng Huang

Driver Team

© Cortina Systems, Inc. 2012 All Rights Reserved Proprietary and Confidential 1 © Cortina Systems, Inc. 2012 All Rights Reserved Proprietary and Confidential

Outline

Standards overview

System architecture

Framing and MAC

Activation method

OMCI overview


ITU-T Rec.

G.984.1: general characteristics

Bit rate

Logical / Physical reach

Split ratio

etc.

G.984.2: PMD layer specification

Line code

Wavelength

etc.

G.984.3: TC layer specification

TC layer framing

PLOAM

ONU activation

etc.

G.984.4/G.988: OMCI specification


GPON vs. EPON

ITEM GPON EPON

OAM Mandatory eOAM/PLOAM/OMCI

Optional and private

MAC Layer Service Ether/TDM/SDH/etc. Ether

Frame GEM frame Ethernet frame

Physical Layer Bit rate Down: 1.25G, 2.5Gbps Up: 1.25Gbps

Down and Up: 1.25Gbps

Distance 10 / 20 km (Logical: 60 km)

10 / 20 km

Split ratio 1:64 (Logical: 128) 1: 16 or over

Line code NRZ 8B/10B


GPON Multiplexing

ONU-ID ONU

Alloc-ID T-CONT

GEM-ID GEM Port


ONU Identifier

ONU-ID is a 8-bit identifier

Assigned by OLT during activation using the PLOAM messaging channel

Used in PLOAM

Equal to default Alloc-ID

Assignable range: 0..253

Broadcast ONU-ID: 255

used in broadcast PLOAMd or by unassigned ONU in PLOAMu


T-CONT

Basic upstream container

Associated with one Alloc-ID

Each T-CONT has a traffic profile

DBA report and grant based on it

Fixed number discovered via OMCC (ANI-G)

OMCC is mapped to Default Alloc-ID

Five types


Alloc-ID

Identify a traffic-bearing entity that is a recipient of upstream bandwidth

allocations

Represented either by a T-CONT or by the upstream OMCC channel

Default Alloc-ID

implicitly assigned

equal to ONU-ID

used to carry the upstream PLOAM and OMCC traffic

range: 0..253

Additional Alloc-IDs

assigned explicitly using the “Assign_Alloc-ID” PLOAM message

range: 256..4095

Broadcast Alloc-ID

=254

used by OLT in a serial number request event


GEM Port

A GEM port represent an traffic flow

Globally unique

Each GEM port bears one kind of service traffic ( i.e. a T-CONT type )

Scheduling via GEM port to T-CONT mapping

Mapping of T-CONTs to Alloc-IDs is performed via the OMCC

GEM Port-ID range: 0..4095


Protocol stack


GTC frame structure


Downstream GTC frame


PSync state-machine

The recommended value for M1 is 2.

The recommended value for M2 is 5.


IDENT field

FEC Ind: Indicate whether FEC is being used in downstream.

Superframe counter:

ONU load it into local counter in Hunt state, and compare it when in Pre-sync and Sync

states.

employed by the encryption system


PLOAM

ONU activation

OMCC establishment

Encryption configuration

Key management

Alarm signaling


Plend field

Blen: Number of allocation, granted in 125us, up to 4095

Blen==0 means empty BWmap


BWmap fields


Allocation fields

Alloc-ID: Indicate a particular T-CONT or OMCC

Flags field：

Bit 10：Indicate whether the ONU shall send an PLOAMu

Bit 9：Inicate whether FEC parity shall be inserted during this allocation

Bit 8 and 7：Indicate DBRu (mode)

00: Do not send DBRu at all.

01: Send the "Mode 0" DBRu (two bytes).

10: Send the "Mode 1" DBRu (three bytes).

StartTime: 16-bit number that indicates the starting time of the allocation

measured in bytes

not include the PLOu

StopTime: 16-bit number that indicates the stopping time of the allocation

points to the last valid data byte associated with this allocation

within the frame in which the allocation began

CRC field


Upstream GTC burst


Upstream overhead


PLOu fields

Preamble

Delimiter

BIP: bit error rate estimation

ONU-ID: assigned ONU-ID or 255

Ind:

Bit 7 (MSB): Urgent PLOAMu waiting

Bit 6: FEC status

Bit 5: RDI status


DBA methods

Status reporting (SR)

based on explicit buffer occupancy reports

Traffic monitoring (TM)

based on OLT's observation of the idle GEM frame

DBRu modes

Mode 0: One-octet coding of total amount of data

Mode 1: Two one-octet coding. First is the data marked as “yellow” and the second is

the data marked as “green”


GEM frame format


GEM header fields

PLI: indicate the length of the payload

Port-ID: GEM port ID

PTI: indicate the content type of the payload

000: User data fragment, not the end of a frame

001: User data fragment, end of a frame

100: GEM OAM, not the end of a frame

101: GEM OAM, end of a frame

others: Reserved

HEC: provides error detection and correction for the header


GEM frame delineation


GEM user frame fragmentation

A user data fragment cannot straddle a GTC frame boundary


MAC example


Activation - Process

Three Phases

Parameter Learning (used in the upstream transmission)

pre-assigned delay

number of preamble bytes

optical power level

Serial Number Acquisition (assigns the ONU-ID)

Ranging (compute the EqD)

Exchange of upstream and downstream PLOAM messages


Activation - ONU State Machine


Timing of serial number acquisition


Equalization delay measurements


OMCI overview

A dedicated bidirectional virtual connection (OMCC GEM port)

PDU has fixed 48-bytes in length

Packet format

Transaction correlation identifier: avoid ambiguous responses

Message type

Bit 6: AR, require an ack or not

Bit 5: AK, is an ack message or not

Bit 4..0: MT, message type

create, delete, set, get, MIB upload, start software download, etc.

Device identifier: 0x0A for baseline OMCI message; 0x0B for extended

OMCI message

Message entity identifier: class-ID + instance-ID


MEs relationship example


Reference

ITU-T Recommendation G.984.1, 2008.




GPON Technology and iROS™ Development, Charles Chen, 2007


Thanks for your attention

Q&A

Documents

GPON Introductioncspace.userapp.com/cspace/CORTINA/1387333165303448005308.pdf · GPON Introduction Chengcheng Huang ... GPON vs. EPON ITEM GPON EPON OAM Mandatory eOAM/PLOAM/OMCI