DR-MPCP: Delayed REPORT message for MultiPoint Control Protocol in EPON Speaker: Chia-Chih Chien Advisor: Dr. Ho-Ting Wu Date: 2015/11/26 1

Outline  Introduction  Queueing Analysis  Analysis of DR-MPCP  Theoretical Analysis  Simulation  Conclusion  Reference 2

Introduction  The link in EPON is shared by multiple optical network units (ONUs) at customers’ premises, an optical line terminal (OLT) at a central office is connected to a single fiber that has an optical splitter for all ONUs. 3 ONU OLT ONU splitter downstream upstream

Introduction(Cont.)  The downlink, which means the communication to the ONU from the OLT, is a broadcast medium where the OLT transmits the data to all ONUs.  In the uplink access, which means the communication to the OLT from the ONU, time division multiple access (TDMA) is used.  Dynamic bandwidth allocation (DBA) for time scheduling of packets is required to avoid collisions of the packets. In the DBA scheme, each ONU sends the transmission request to an OLT, and then each ONU can reserve the network resources by the reply from the OLT. 4

Introduction(Cont.)  The Multi-Point Control Protocol(MPCP) is a communication framework to enable the exchange of control information in a point-to-multi-point(P2MP) topology network.  In MPCP, each ONU sends the transmission request amount (the amount of data in the queue) to the OLT as a 64-byte REPORT message.  The OLT calculates both the transmission time and the transmission starting time of each ONU. The OLT sends both the calculated transmission window and transmission starting time to each ONU as a 64-byte GATE message. 5

Introduction(Cont.)  In EPON with MPCP, interleaved polling with adaptive cycle time (IPACT) is a common polling scheme.  The communication time in the uplink is divided into a reservation interval for the control packet transmission and data interval for the packet transmission.  In IPACT, its reservation interval is transmitted after its data interval.  The waiting time of the arriving packet (packet delay) is long when the packet arrives after the reservation interval of MPCP in IPACT. 6

Introduction(Cont.)  In this paper, to decrease the mean packet delay time, propose a novel reservation interval allocation method (DR-MPCP: Delayed Report messages-MPCP) in which the transmission timing of the REPORT message is delayed. 7

Queueing Analysis  The polling system can transmit the reservation packets in a multiplex manner when the multi-access channel can transmit only one user at a certain moment. 8

Queueing Analysis(Cont.)  The residual time component W i F is the remaining time until the ongoing reservation is completed.  The service time component W i Q is the time for transmissions of packets ahead of packet i.  The reservation time component W i R is the sum of time for the reservation intervals until the packet I is transmitted. 9

Analysis of DR-MPCP: System Model  Each ONU has a queue for the arriving packets.  The buffer size of each ONU is larger than the sum of all arriving packet sizes. 10

Analysis of DR-MPCP: System Model(Cont.)  Each arrival packet waits in the queue until the GATE message is received from OLT.  Waiting packets are transmitted in accordance with the assigned transmission window in FIFO (First-In-First- Out).  The guard time is set between the reservation and data intervals in order to switch to another ONU. 11

Analysis of DR-MPCP: System Model(Cont.)  To decrease the mean packet delay, propose a novel allocation method for the reservation interval(DR-MPCP method) that delays transmission timing of m ONUs for REPORT messages. 12

Analysis of DR-MPCP: System Model(Cont.)  To realize the DR-MPCP method, each ONU need to know the m of the transmission for REPORT messages.  GATE message for the registration process is broadcasted to all ONUs.  By writing the REPORT sift amount to the expansion slot of this GATE message, all ONUs can know m. 13

Analysis of DR-MPCP: Difference of Three Methods  EPON based on IPACT connecting N ONUs can be treated equally with the traditional polling system for N users.  Each ONU repeats data and reservation intervals alternately. 14

Analysis of DR-MPCP: Difference of Three Methods(Cont.) 15 aArrival time rReported time for REPORT message tTransmitted time of the waiting packet

Analysis of DR-MPCP: Difference of Three Methods(Cont.) 16  Thus, the delay time of this packet can be calculated by the difference t − a.

Analysis of DR-MPCP: Difference of Three Methods(Cont.) 17  In the traditional method, the reservation interval is set before the beginning of the data interval.  When the RTT (Round-Trip time) is long, the GATE message arrives with a delay.  Thus, when EPON uses the traditional method, the idle time occurs in which data cannot be transmitted because the waiting packets need to be transmitted immediately after sending REPORT message.

Analysis of DR-MPCP: Difference of Three Methods(Cont.) 18  In the IPACT method, the data interval is set before the beginning of the reservation interval.  If the packet arrives after the reservation interval has finished, the request timing for the packet (REPORT message) is the next cycle.  Thus, the packet transmission timing is the cycle after next.  In this situation, the packet delay becomes very long.

Analysis of DR-MPCP  The transmission times are divided into two areas in accordance with the packet arrival time before or after its own REPORT message.  The patterns are divided into four patterns in accordance with the packet arrival time of the data or reservation interval. 19

Analysis of DR-MPCP(Cont.) 20

Analysis of DR-MPCP(Cont.) 21 NNumber of ONU ρTraffic load nONU number mREPORT sift amount

Theoretical Analysis 22 NNumber of ONU ρTraffic load λPoisson distribution mREPORT sift amount Variance of the reservation interval The first two moments of each packet service time The first two moments of each reservation time

Theoretical Analysis(Cont.) 23

Theoretical Analysis(Cont.)  Confirm that the efficiency of mean packet delay depends on the REPORT sift amount m and traffic intensity ρ, surprisingly but not on the number of ONUs N. 24

Simulation  The numbers of ONUs are set to 8, 16 and 32.  The bandwidth of uplink is set to C up = 1 Gb/s.  The guard time t g is set to.  The mean reservation time is.  The variance. 25

Simulation(Cont.) 26

Simulation(Cont.) 27

Conclusion  To decrease the mean packet delay time, proposed a novel reservation interval allocation method(DR-MPCP method) that delays the transmission timing of the REPORT message.  By using DR-MPCP, I observed that the mean packet delay can decrease much more than by using the IPACT method.  I found that the efficiency of mean packet delay depends on the REPORT sift amount m and traffic intensity ρ but on the number of ONUs. 28

Reference  Sumiko Miyata, Ken-ichi Baba, Katsunori Yamaoka, and Hirostsugu Kinoshita, “DR-MPCP: Delayed REPORT message for MultiPoint Control Protocol in EPON,” International Workshop on Reliable Network Design and Modeling, pp , Oct

Thanks for listening 30