MPCP: Auto Discovery. 1 IEEE 802.3ah

Transcription

1 1 IEEE 802.3ah MPCP: Auto Discovery Onn Haran, Passave Ajay Gummalla, Broadcom Ariel Maislos, Passave Dolors Sala, Broadcom Hiroshi Suzuki, Cisco Systems Jian Song, Salira John Limb, Broadcom Lior Khermosh, Passave Osamu Yoshihara, NTT Vincent Bemmel, Alloptic Yukihiro Fujimoto, NTT

2 2 IEEE 802.3ah Problem Description How to harmonize a new ONU into a PON Knowing it s there Knowing who it is Assigning ports in P2PE Compensating for RTD Negotiating network parameters

3 3 IEEE 802.3ah Auto-discovery Background ONU address is unknown Discovery should be broadcast to all stations ONUs can wake-up independently Discovery should deal with contention in ONU responses Discovery is performed perpetually RTD to ONU is unknown OLT should allocate big enough discovery slot

4 4 IEEE 802.3ah Discovery and MP2PE P2PE is not active before discovery, and PHY IDs are not assigned A discovery PHY ID (=0?) is pre-assigned following reset A logical link is established between OLT to all undiscovered ONUs Discovery PHY ID is used until channel establishment

5 5 IEEE 802.3ah Virtual MAC Instances Before registration After registration MA_control_ request MA_control_ indication MAC control sublayer MA_ control_ request MA_ control_ indication MA_ data_ request MAC control sublayer MA_ data_ indication MA_ control_ request MA_ control_ indication MA_ data_ request MAC control sublayer MA_ data_ indication Transmit frame Receive frame Medium Access Control Discovery instance Transmit frame Receive frame Medium Access Control Transmit frame Receive frame Medium Access Control Multiple virtual MAC instances

6 6 IEEE 802.3ah Discovery Protocol A globally assigned multicast address may be used (for example, Pause): C A GATE message creates a transmission opportunity to unregistered devices REGISTER_REQUEST, REGISTER and REGISTER_ACK messages complete the protocol Contention is solved by ONU time-out on REGISTER message

7 Sequence Summary OLT ONU GATE (dest_addr=multicast, content = GRANT+OLT capabilities) REGISTER_REQUEST(content=PHY ID capabilities+onu capabilities+echo of OLT capabilities) CONTENTION ZONE REGISTER (dest_addr=onu MAC addr, content=phy ID list+echo of ONU capabilities) GATE (dest_addr=onu MAC addr, content = GRANT) REGISTER_ACK(content = echo of registered PHY ID) Channel established 7 IEEE 802.3ah

8 8 IEEE 802.3ah GATE Message OLT transmits a GATE message with the following parameters: Number of grants: 1 Grant type: discovery grant Grant #1 start: First time to expect REGISTER_REQUEST Grant #1 length: Bigger than duration of one register packet transmission OLT optional capabilities OLT vendor extensions OLT should allocate reception window in the size of: <Grant length> + <maximal round trip delay>

9 9 IEEE 802.3ah Registration Behavior ONU responds only if received PHY ID matches discovery PHY ID and grant type is discovery ONU must have a REGISTER_REQUEST packet ready ONU starts to transmit randomly between <Grant start> and <Grant start> + <Grant length> <duration of one register packet transmission> Destination address is OLT multicast address ONU MAC address is reported in src_addr field For security reasons, a random MAC ADDR may be used, though it is useless without a complete security solution

10 10 IEEE 802.3ah REGISTER_REQUEST Message Logical PHY ID registration is static by nature and can be performed only during discovery phase REGISTER_REQUEST message contains the following parameters: Number of shared media MACs [0..1] Number of P2PE MACs [0..TBD] ONU optional capabilities ONU vendor extensions Echo of understood OLT capabilities

11 11 IEEE 802.3ah GATE and REGISTER_REQ Discovery Slot Round trip time #1+ Random delay #1 Round trip time #2+ Random delay #2 OLT TX RX Discovery GATE REGISTER_ REQUEST REGISTER_ REQUEST ONU #1 TX RX Discovery GATE Slot start REGISTER_ REQUEST Random delay ONU #2 TX RX Discovery GATE Slot start REGISTER_ REQUEST Random delay

12 12 IEEE 802.3ah REGISTER Message REGISTER message contains the following parameters: Destination address: ONU MAC address Number of shared media MACs assigned Shared media PHY ID value (U/M bit is set to M) Number of P2P MACs assigned List of P2P PHY IDs (U/M bit is set to U) Echo of understood ONU capabilities

13 13 IEEE 802.3ah REGISTER_ACK Message ONU sends REGISTER_ACK message at the first grant opportunity (grant type = regular) The registered PHY IDs are reported to guarantee creation of virtual MAC instances Allows ONU to convey non-support for an OLT capability requested in prior message, e.g.: Not enough resources remaining to support it at present time Request not understood Request out of range

14 14 IEEE 802.3ah Sequence 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 must respond to query GATE if it hasn t received a REGISTER message after sending a REGISTER_REQUEST message Reset / timeout should be investigated

15 15 IEEE 802.3ah Discovery Convergence Some sort of randomization must be applied in ONU responses to discovery Two options are investigated: ONU skips (ignores) random number of discovery opportunities after previous ONU response wasn t acknowledged Graph is showing exponentially growing backoff ONU responds to every discovery opportunity using a random delay within the discovery grant Graph is showing a scenario in which up to 8 ONUs can be registered at one attempt: grant length = 16*(packet length+switching time)

16 Convergence Comparison 50 Tries expecteny until all registered Random start time Random GATE skip Number of ONUs trying to register 16 IEEE 802.3ah

17 17 IEEE 802.3ah Summary Auto-discovery protocol enabling ONU plug-andplay includes: MP2PE registration RTT measurement Capabilities negotiation Efficient collision-avoidance scheme was suggested