MPCP (Multipoint Control protocol) Professor : Ho-Ting Wu Speaker : 簡睿毅

Outline Overview EPON MPCP Summary

Outline Overview EPON MPCP Summary

PON (Passive Optical Network ) Features of a passive optical network: an attractive solution to implement FTTB (fiber to the build) and FTTH (fiber to the home)access networks FTTH deployment scenarios a point-to-multipoint optical network only passive optical components: Couplers and Splitters two primary types of PON technologies: ATM PON (APON) Ethernet PON (EPON)

FTTH deployment scenarios

Architecture of PONs OLT: Optical Line Terminal ONU: Optical Network Unit

Ethernet PON EPON started to be standardized by IEEE 802.3ah EFM since 2001 Ethernet is a ubiquitous technology: deployed widely in LAN, MAN and WAN Ethernet is more attractive to PON than ATM high speed: up to 10 Gigabit/s lower cost of Ethernet equipments than those of ATM easier interoperability than that in ATM lower overhead

Features of Ethernet PON All data packets carried in EPON are encapsulated in Ethernet frames Broadcasting in the downstream direction from the OLT to ONUs Sharing the upstream channel capacity among ONUs Collision will occur when different ONUs transmit data simultaneously Method is needed for multiple access — Medium Access Control (MAC) protocols

Downstream traffic in EPON

Upstream traffic in EPON

Outline Overview EPON MPCP Summary

MPCP (Multipoint Control protocol) Introduction Two mode of operation Discovery Protocol RTT (Round-trip time) measurement Messages Format Messages Operation MPCP-Goals

MPCP (Multipoint Control protocol) Introduction Two mode of operation Discovery Protocol RTT (Round-trip time) measurement Messages Format Messages Operation MPCP-Goals

Basic Characteristics The Multi-Point Control Protocol (MPCP) specifies a control mechanism between a Master unit and Slaves units connected to a Point-to-Multi-Point (P2MP) segment to allow efficient transmission of data MPCP is implemented in MAC Control layer MPCP uses five MAC Control messages - GATE, REPORT, REGISTER_REQ,REGISTER,REGISTER_ACK

MPCP (Multipoint Control protocol) Introduction Two mode of operation Discovery Protocol RTT (Round-trip time) measurement Messages Format Messages Operation MPCP-Goals

Two mode of operation Auto Discovery mode - to detect newly connected ONUs and learn the round-trip delay and MAC address of that ONU Normal mode - to assign transmission opportunities to all initialized ONUs

Auto Discovery mode (1/2) OLT allocates an initialization slot, an interval of time when no previously initialized ONUs are allowed to transmit OLT sends an initialization GATE message advertising the start time of the initialization slot and its length Only un-initialized ONUs will respond to the initialization GATE message

Auto Discovery mode (2/2) When the local clock located in the ONU reaches the start time of the initialization slot ,the ONU will transmit its own message (initialization REPORT) When the OLT receives the REPORT from an un-initialized ONU, it learns its MAC address and round-trip time

MPCP (Multipoint Control protocol) Introduction Two mode of operation Discovery Protocol RTT (Round-trip time) measurement Messages Format Messages Operation MPCP-Goals

Discovery Protocol Four MAC control messages – Discovery GATE: Creates transmission opportunity for undiscovered devices – Register_Request: ONU response to “Discovery Gate” – Register: OLT response to Register_Request – Register_Ack: ONU response to Register ONUs can wake-up Simultaneously – Protocol must deal with contention in Register_Requests Multiple ONUs can potentially be registered within single Discovery time period

Auto Discovery

ONU Behavior During Discovery At Power-up / Reset, an ONU enters Discovery State: – Undiscovered ONUs Await Reception of “Discovery Gate” message from OLT Unregistered ONU responds only: – If received message’s Logical Link ID(LLID) matches discovery/default LLID and the grant type is discovery

OLT Behavior During Discovery OLT Must Periodically Reserve Time Periods for Discovery –The Frequency of discovery windows can be chosen for desired overhead Since Undiscovered ONU Addresses are Unknown – “Discovery Gates” are broadcast to all ONUs

Failure Modes OLT assumes ONU is unregistered if: – REGISTER_ACK message wasn’t received at the first grant opportunity – ONU responds to “Discovery GATE” messages ONU assumes it is unregistered if: – After sending a REGISTER_REQUEST message, it receives a “Discovery GATE” before receiving a REGISTER message – After sending a REGISTER_ACK message, it receives a “Discovery GATE” before receiving a “Normal GATE” message

Resolving Discovery Contention Some sort of randomization must be applied to ONU Register messages to minimize collisions

MPCP (Multipoint Control protocol) Introduction Two mode of operation Discovery Protocol RTT (Round-trip time) measurement Messages Format Messages Operation MPCP-Goals

RTT measurement

MPCP (Multipoint Control protocol) Introduction Two mode of operation Discovery Protocol RTT (Round-trip time) measurement Messages Format Messages Operation MPCP-Goals

Messages Format OLTONU GATE , REGISTER ONUOLT REPORT , REGISTER_REQUEST , REGISTER_ACK Used only during discovery process REGISTER , REGISTER_REQUEST , REGISTER_ACK

GATE/REPORT Behavior Protocol layer conveys information - OLTONU bandwidth assignment - ONU OLT bandwidth request Service layer sitting above makes decisions - OLT bandwidth allocation - ONU bandwidth utilization OLT sends GATE messages to ONU and guarantees no overlaps

MPCP (Multipoint Control protocol) Introduction Two mode of operation Discovery Protocol RTT (Round-trip time) measurement Messages Format Messages Operation MPCP-Goals

GATE Operation(1/2)

GATE Operation(2/2) ONU transmits only during the time indicated in the GATE ONU MAC-control enables PHY transmission at the start of a GATE duration and disables it at the end of the GATE duration GATE messages can be used with timestamps only

REPORT Operation(1/3)

REPORT Operation(2/3) REPORTs are generated in ONU MAC control client - Indicate local conditions to OLT REPORTs pass through the MAC-control REPORTs are optional

REPORT Operation(3/3) 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 only

MPCP (Multipoint Control protocol) Introduction Two mode of operation Discovery Protocol RTT (Round-trip time) measurement Messages Format Messages Operation MPCP-Goals

MPCP- Goals Optimize Network Resources Address Service Provider Requirements

Outline Overview EPON MPCP Summary

Point-to-Point Emulation (PtPE)

Shared-Medium Emulation (SME)

Combined PtPE and SME Mode

Summary MPCP is compliant with deployed Ethernet by using P2P Emulation layer An 802.3ah point-to-multipoint network is a layer 2 domain with a Bridge at the OLT having a direct link to each ONU Traditional Ethernet framing is maintained Peer-to-peer communications can be disabled at bridge MPCP is confined to one sub-layer – MAC Control MPCP allows higher layer to implement various DBA algorithms

Reference Ethernet Passive Optical Network (EPON) Glen Kramer, University of California, Davis Biswanath Mukherjee, University of California, Davis Ariel Maislos, Passave Networks, Israel Supporting differentiated classes of service in Ethernet passive optical networks Glen Kramer and Biswanath Mukherjee , University of California, Davis Sudhir Dixit and Yinghua Ye , Center, 5 Wayside Road, Burlington Ryan Hirth , Communications, 755 Baywood Drive, Petaluma