Support for Coordinated Shared Network in 802.1AVB. Jan 08 IEEE AVB WG Philippe Klein

Transcription

1 Support for Coordinated Shared Network in 802.1AVB Jan 08 IEEE AVB WG Philippe Klein

2 This presentation is available online at: avb_phkl-csn

3 What is a Coordinated Shared Network (CSN)? 3 - avb_phkl-csn

4 Coordinated Shared Network (CSN) Time domain multiple access (TDMA) network Coordinated contention free media access controlled by a single elected or designated network controller (NC) Interface for priority (& parameterized) QoS Support both Point to Point and Broadcast traffic The trend of the more recent (OFDM based) home networks : Moca (coax) Homeplug (powerline) HomePNA (copperline) Source: Microsoft Corporation 4 - avb_phkl-csn

5 CSN Support in IEEE AVB Currently not supported by the 802.1AVB umbrella but shares multiple similarities * to the topology if the CSN cloud is an leaf. [*] SN supports node-to-node connections while does not support STA-STA connections (unless Direct Link Protocol is supported) Bridge Bridge AP SN node CSN STA STA SN node SN node Bridge 5 - avb_phkl-csn

6 CSN Backbone Support in IEEE AVB Currently not supported by the 802.1AVB umbrella but CSN backbone support will be needed for STA/Bridges Bridge Bridge AP SN node CSN STA STA SN node SN node Bridge Bridge 6 - avb_phkl-csn

7 Problem Statement 7 - avb_phkl-csn

8 The Facts Are CSNs optimal solutions for AV services? No! Are CSNs been deployed as residential networks? Yes! Will CSNs be used for residential AV services? Yes! Is End to End QoS a prerequisite to any residential SLA (paid per view) service? Yes! Should AVB supports residential networks? Yes! 8 - avb_phkl-csn

9 The Proposal Include support for Coordinated Shared Networks in the 802.1AVB specifications as a generic interface for all CSN Networks: MoCA, HomePlug, network w/ STA-Bridge capabilities, AVB AVB CSN NC AVB NC = Network Controller AVB 9 - avb_phkl-csn

10 AV Bridge / CSN Network Topology Questions 10 - avb_phkl-csn

11 Topology Option #1 CSN Adapter (CSNA) is a / CSN bridge 802 MAC 802 MAC B2B Interface BRIDGE E E MAC Relay 802 CL MAC Relay 802 CL BRIDGE E E B2B Interface CSNA E Bridge #3 E E Bridge #4 CSN MAC CSN PHY CSN MAC CSN PHY E E Bridge #1 E CSNA Bridge #2 B2B Interface CSNA E BRIDGE E E E E CSN link Bridge #3 Bridge #4 PRO CONS Natural decomposition Cascaded bridges Bridge 2 Bridge interface is defined Implementing a full bridge HW/SW functionality might be too expensive for low end adapters Double bridge entities within the same enclosure when co-located 11 - avb_phkl-csn

12 Topology Option #2 CSN Adapter emulates links (CSNA is seen as a PHY) Link Emulation BRIDGE E E 802 MAC 802 MAC BRIDGE CSNA E E E 802 CL 802 CL E E Bridge #3 Bridge #4 CSN MAC CSN PHY CSN MAC CSN PHY E E Bridge #1 E CSNA Bridge #2 CSNA E BRIDGE E E E E CSN link Bridge #3 Bridge #4 PRO CONS Cheaper implementation Could be added as a port to existing AVB bridges CSN access latencies CSN link characteristics might change over time Need a new AVB interface to CSN sub-layer to query CSN characteristics 12 - avb_phkl-csn

13 QoS on Coordinated Shared Networks 13 - avb_phkl-csn

14 Coordinated Shared Network supports: Contention free access Bandwidth reservation: solicited bandwidth unsolicited bandwidth Prioritized QoS: either uses 802.1Q priority levels or maps a subset of priority levels from 802.1Q Parameterized QoS: flow specifications 14 - avb_phkl-csn

15 CSN - Solicited Media Access Pros: Optimized bandwidth usage (Bandwidth on Demand) Cons: Access latency, difficult management for QoS Flows Ingress Packet STA Tx Request Opportunity Network Controller STA Media Access Latency Tx Request Request Grant Packet Transmission 15 - avb_phkl-csn

16 CF Media Access Plan cycle n cycle n+1 cycle n+2 MAP(n+1) MAP(n+2) time MAP(n+1) MAP(n+2) TRO Flow1 TRO Flow2 TRO Flow3 Granted Tx Flow1 Granted Tx Flow1 MAP (n+2) Granted Tx Flow avb_phkl-csn

17 Contention Free Media Access cycle n cycle n+1 cycle n+2 MAP(n+1) TRO Flow1 MAP(n+2) TXOP Flow1 time NC STA Packet j Txm TRQ Pj MAP(n+2) Packet j Txm time Ingress Data Packet j of Flow i Arrival Bandwidth Rsv Request for Packet j Media Access Latency 17 - avb_phkl-csn

18 Unsolicited Media Access Pros: Bandwidth management, QoS, low latency Cons: Wasted bandwidth for bursty flows MAP cycle i TXOP Flow 1 time TXOP time ( t from Start of cycle) TXOP Flow1 TXOP Flow2 TXOP Flow1 TXOP Flow1 TXOP Flow2 TXOP Service time ( t from TXOP to TXOP) for Flow1 time TXOP Service time for Flow avb_phkl-csn

19 QoS Flow Parameters for AVB/CSN 19 - avb_phkl-csn

20 QoS Flow Parameter Comparison AVB MoCA e upnp QoS v3 HomePlug v1.1 HPNA v3 TSPEC TSPEC TSPEC TSPEC CSPEC Service Flow Max Bit Rate Peak Data Rate Mean, Peak & Min Data Rates Mean, Peak & Min Data Rates Average, Max & Min Data Rate Average, Max & Min Data Rate Max Frame Rate (Max) Burst Size Burst Size Max Burst Size Max Burst Size (Max) Packet Size Nominal & Max MSDU Sizes Max Packet Size Mean & Max MSDU Sizes Nominal Packet Size Medium Time (access s max latency) Reserved Service Rate Delay Bound (MAC End to End max latency) End to End Max Delay High Delay Bound Max Latency End to End Max Jitter Jitter Bound Max Jitter Minimum & Max Service Intervals Min & Max Service Intervals Min & Max Inter-TXOP time TX timeslot (within the MAP cycle) Surplus Bandwidth Allowance Surplus Bandwidth Loss Sensitivity (max size frames/sec) MSDU Error Rate Requirement Service Level BER Requirement Min PHY Rate QosSegment Max Delay High & Max Jitter Arrival Time Stamp tolerance at TX CL SAP 20 - avb_phkl-csn

21 Questions 21 - avb_phkl-csn

22 #1: Path Delay Measurement AVB1 CSNA1 CSNA link 1 CSN link link 2 AVB2 Pdelay_req? CSN_MSG [Pdelay_req] Pdelay_req Pdelay_resp = Σ link_dealy (1,2) Σ link_delay(1,csn,2)? CSN_MSG [Pdealy_resp = link_2 delay] Pdelay_resp = link_2 delay Option #1: Pdelay = Σ Pdelay (l1,csn,l2) CSN delay to high for current P2P link selection (AVB capable path) Option #2: Pdelay = Σ Pdelay (l1,l2) Not reporting the CSN delay ( cheating mode ) will not work if AVB establish the data link cost of the data STP based on Pdelay Is MSTP / 802.1s a solution to create specific data spanning tree per CoS? 22 - avb_phkl-csn

23 #2: Credit Based Shaper with Sub Layer Queuing Sub-layer interface SHAPER Tx Flow Shaped Flow CSN Tx Flow IBQ EBQ IAQ EAQ Shaped Flow Rx Flow CSN Rx Flow CSN EBQ IBQ EAQ IAQ AVB Shaper Parameters: lolimit = maxframesize * (sendslope/linktransmitrate) hilimit = (max interference size) * (idleslope/linktransmitrate) max burst size = (linktransmitrate x ((hilimit+lolimit)/sendslope)) maxframesize linktransmitrate maxburstsize CSN Adapter CSN Parameters (queried during SRP reservation) Flow Control 23 - avb_phkl-csn

24 802.1AS Clock Synchronization on CSN 24 - avb_phkl-csn

25 SN AVB Timing Services AVB Timing Services If the CSN clock is accurate enough, the 802.1as CSN media dependant part could be provided by the CSN time services: NC s master clock periodically (~1 100ms) broadcasted to all CSNAs CSNAs local timer synchronized on NC s master clock references Time-Stamped Txm frames AVB CSN Timing SAP: Sync, Follow_Up, Pdelay_Req, Pdelay_Resp, Pdelay_Resp_Follow_Up 25 - avb_phkl-csn

26 Link Delay SAP AVB CSNA Pdelay_Req T 1 t 1 Pdelay_Resp t 2 T 2 Pdelay_FU (t 1,t 2 ) LinkDelay* = ( (T 2 -T 1 ) - (t 2 -t 1 ) ) / 2 * In most cases,csna will be co-located on the AVB board and LinkDelay will be = avb_phkl-csn

27 CSN Propagation Delay Measurement between 2 CSNAs CSNA a CSN CSNA b CSNA a CSN CSNA b ta 1 CSN Pd_Request() [ta 1 ] ta 1 CSN Pd_Request() tb 1 tb 1 ta 2 CSN Pd_Resp(tb 1 ) [tb 2 ] tb 2 ta 2 CSN Pd_Resp(tb 1 ) CSN Pd_Resp_FU(tb 2 ) tb 2 w/i Txm packet timestamps w/o Txm packet timestamps CSN_PropagationDelay = ( (ta 2 -ta 1 ) - (tb 2 -tb 1 ) ) / 2 [t] Tx Packet Header s TimeStamp (t) API Parameters 27 - avb_phkl-csn

28 Scheme 1: Clock Sync w/o CSN Master Clock Ref AVB a Sync () T 1 ta 1 CSNA a CSN CSNA b ld a pd a-b ld b FRC ta FRC tb AVB b Sync_FU (T 1 ) GT ta1 = T 1 + ld a CSN Sync () ta 2 GT ta2 = GT ta1 + T(ta 2 -ta 1 ) tb 1 CSN Sync_FU (GT ta2 ) GT tb1 = GT ta2 + pd a-b tb 2 Sync () GT tb2 = GT tb1 + T(tb 2 -tb 1 ) Sync_FU (GT tb2 ) GT = AVB Grand Time FRC = free running clock ld = AVB - SNA link delay tx i = free running clock time pd = SN propagation delay 28 - avb_phkl-csn

29 Scheme 2: Clock Sync w/ CSN Master Clock Ref AVB a ld a Sync () T 1 ta 1 CSNA a CSN CSNA b LCSNC ta CSN Clock CSNC Sync CSNC Sync LCSNC tb ld b AVB b Sync_FU (T 1 ) GT ta1 = T 1 + ld a t = GT ta1 ta 1 ~ ~ CSN GT Sync ( t ) tb 1 ~ ~ Sync () GT tb1 = tb 1 + t Sync_FU (GT tb1 ) GT = AVB Grand Time LCSNC = Local CSN Clock ld = AVB - CSNA link delay tx i = Local CSN Clock time pd = CSN propagation delay 29 - avb_phkl-csn

30 Thank you