Group meeting ppt

Speaker : Pei-Hwa Yin

EPON Introduction1OutlineIntroductionMPCP (Multi Point Control Protocol )DBA introduction -IPACT (Interleaved Polling with Adaptive Cycle Time ) -Priority QueuingFuture workReference

2IntroductionDevelop motivation :

backbone bandwidth has experienced substantial growth , but little has changed in the access Network

PON is one of solution to this problem due to -low cost -high bandwidth -easy to maintain

3backbone network bandwidth~end user , , bandwidth3IntroductionPON : passive optical network - no active elements in the transmission path from source to destination

Three basic components :

a )OLT (optical line terminal) : - near service provider (control and modify bandwidth) - connect to the backbone network( ex : IP )b )ONU (optical network unit) : - near end-users c ) 1:N passive star coupler(splitter or combiner) : - splitter(use in downstream direction) - combiner(use in upstream direction)

4IntroductionThree common topology type a ) tree (use most) b ) bus c ) ring

5IntroductionEPON : all data are encapsulated in Ethernet frames for transmission

Feature : - long distance : 20 km- more cost effective- higher bandwidth : up to 10Gigabit/second

Ethernet frame format

6SFD : signal the start of the actual frame (Start Frame Delimiter)Preamble : a pattern of altering 0 or 1 bits use to synchronizationEther Type :The number of bytes encapsulated or theprotocoltype of the next higher protocolFCS: frame check sequence6IntroductionUpstream direction : ONU->OLT : ONUs share the channel capacity /use TDMA mechanism that control by OLT

Downstream direction :OLT->ONU : broadcasting

7The ONUs filter the downlink traffic that is not intended for their reception, according to LLID7MPCP(Multi Point Control protocol )a control mechanism between a Master and Slaves units connected to a Point-to-Multi-Point (P2MP) segment to allow efficient transmission of data

- EPON use this protocol to transfer control message between OLT and ONU

- It is a layer 2 protocol

- Two mode a)normal mode Bandwidth assignment / request b) Auto Discovery mode Control Auto Discovery process

88MPCP(Multi Point Control protocol )Control message are as follows (defined by opcode field): -GATE -REPORT -REGISTER_REQ -REGISTER -REGISTER_ACK

99MPCP(Multi Point Control protocol )Gate message format

Ps : flag=0/regular flag=1/discover

101 ONU transmits only during the time indicated in the grant2 ONU MAC-control enables PHY transmission at the start of a grant duration and disables it at the end of the grant duration3 Multiple grants may be outstanding up to a limit4 ONU is free to use granted period to its best ability5 GATE messages can be used with timestamps only

10MPCP(Multi Point Control protocol )Gate message operation

11The time stamp is the value of PON counter at the moment MAC control passed the frame to the MAC

ONU must update its local PON counter when receiving any valid message

11MPCP(Multi Point Control protocol )Report message format

12 A bit mask specifies the queues reported A REPORT message may contain queue reports The OLT must process REPORT messages The OLT may consider the REPORT when allocating bandwidth The ONU must issue REPORTs periodically REPORT messages can be used with timestamps only12MPCP(Multi Point Control protocol )Report message operation

1313MPCP(Multi Point Control protocol )Round Trip Time Measurement- Raging

14MPCP(Multi Point Control protocol )Normal mode

15MPCP(Multi Point Control protocol )Auto-discover mode

Which are used to discover and register a newly connected ONU

16and to collect relevant information about that ONU, such as the round-trip delay and MAC address

First send gate message(auto-discovery mode)1) Announces when discovery window ( contention zone ) will open (broadcasting)2) In this time period if OLT receive register-req from non registered ONU( including its Mac address)3) OLT will send register to ONU(assign LLID to this ONU)

5)

To avoid collision (because may be there are more than one ONU wants to register )16DBA framework

DBA framework overview I

17DBA framework

DBA framework overview II

18Inter-ONU Scheduling-IPACT Step 1 OLT throw Grant/request mechanism has already know the information that bandwidth allocation need and the information are store in a polling table , then OLT will send a message to notify the first ONU the time that can start to transmit data(include data size) Step 2 when ONU get message , it will start to transmit data in the end ,it will send another message to OLT ,to notify how many data that need to transmit next time Step 3 in a proper time OLT will send a grant message to the next ONUrepeat 1~3 until end

19OLT polls ONUs individually & issues transmission grants to them in round-robin way

19Inter-ONU Scheduling-IPACTEX:

20Inter-ONU Scheduling-IPACTIf an ONU emptied its buffer completely, it will report 0 bytes back to the OLT.

Correspondingly, in the next cycle the ONU willbe granted 0 bytes, i.e., it will be allowed tosend a new request, but no data.

At the end of its transmission window, ONU will generate its own control message (Request) and send it Back to the OLT

21Inter-ONU Scheduling-IPACTTransmission window size -to notify how many data that OLT can send to a ONUMaximum transmission window : -to avoid ONUs with high traffic volumes monopolize the bandwidth

Type -FIX -Limited -Gated -Constant Credited -Linear credit -Elastic22Inter-ONU Scheduling-IPACTMax polling cycle time :

If all ONU want to transmit data

If only one ONU wants to transmit data

23Inter-ONU Scheduling-IPACTFix :

Limited :

Gated :

Constant credit

24Inter-ONU Scheduling-IPACT25Linear Credit :

Elastic :

Intra-ONU scheduling- priority queuing26Concept and feature :

-Packets are classified by the system and then put in different priority queues

- With in each of the priority queues , packet are scheduled as FIFO queue

- Packet can scheduled if all higher priority queues are emptied

limitation :Low priority queue may suffer starvation

Benefits :Can provide simple QoS

Intra-ONU scheduling- priority queuing

27Future work-Long reach PON

-QoS base of Dynamic Bandwidth Management in Integrated EPON and 802.16 Access Networks

28References[1] Glen Kramer , Davis Biswanath Mukherjee, Gerry Pesavento ,Interleaved Polling with Adaptive Cycle Time (IPACT) A Dynamic Bandwidth Distribution Scheme in an. Optical Access Network,Photonic Network Communications ,4 : 1 ,89-107, 2002[2] N. Ghani, A. Shami, C. Assi, M. Y. A. Raja, Intra-ONU Bandwidth Scheduling in Ethernet Passive Optical Networks,IEEE COMMUNICATIONS LETTERS, VOL. 8, NO. 11, NOVEMBER 2004[3] IEEE 802.3ah 2004[4] RFC4837 Managed Objects of Ethernet Passive Optical Networks ,July 2007292930 Q&A