“Your Flight Will be Delayed by 20 ms” – Understanding Latency in MoIP Networks – Andreas Hildebrand — ALC NetworX

Presenters : Andreas Hildebrand - ALC NetworX

Year : 2022

dlp_document_download : # 1Understanding Latency in AoIPSystemsMoIPPavilion @ AES New York 2022Andreas Hildebrand, ALC NetworX"Your Flight Will Be Delayed by 20 ms" # 2Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) Andreas Hildebrand, RAVENNA Technology Evangelist•more than 25 years in the professional audio / broadcasting industry•graduate diploma in computer science•R&D, project& productmanagementexperience•memberof AES67 TG andST2110 DGALC NetworX GmbH, Munich/ Germany•established2008•R&D center•developing& promotingRAVENNA•Partnershipswith> 40 manufacturersRAVENNA•IP medianetworkingtechnology•designedtomeetrequirementsof professional audio / broadcastingapplications•open technologyapproach, license-free•fully AES67-and SMPTE ST2110-compliant # 3Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) Latency". . . i s a t i m e delay betweenthe causeand the effectof some physical change in the system being observed." [Wiki]". . . i s a consequenceof the limited velocity at which any physical interaction can propagate […] which is always less than the speed of light." [Wiki] # 4Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) (Traditional) Digital Signal Distribution # 5Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) Ve n u eStageboxesAudio RouterEquipment RoomAudio MixerControl RoomTran smi ssi o n(Traditional) Digital Signal Distribution # 6Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) = circuitswitchedroutingVe n u eStageboxesAudio RouterEquipment RoomAudio MixerControl RoomTran smi ssi o n(Traditional) Digital Signal Distributionfixed/ deterministiclatencyfixedconnectionbetweenmicrophoneand mixeroutput # 7Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) 7RAVENNACircuit switching # 8Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) DistanceTime1 m3.3 ns1 km3.3 µs4000 km (NYC –LA)13.3 msto geostationary orbit119 msaround Earth's equator134 msMoon to Earth1.3 sProxima Centauri (nearest star)4.2 yearsacross the Milky Way100,000yearsAndromeda Galaxy (nearest galaxy)2.5 million yearsApproximate light signal travel times # 9Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) NetworkedMedia Distribution=Packet Switching # 10Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) # 11Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) ABIP Packet Switching # 12Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) B1ABA sendsdatapacket toBDestination HeaderPayload DataIP Packet Switching # 13Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) A sendsdatapacket toBB1ABIP Packet Switching # 14Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) A sendsdatapacket toBB1ABIP Packet Switching # 15Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) A sendsdatapacket toBB1ABIP Packet Switching # 16Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) A sendsdatapacket toBB1ABIP Packet Switching # 17Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) A sendsanotherdatapacket toBB2ABIP Packet Switching # 18Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) B2ABA sendsanotherdatapacket toBIP Packet Switching # 19Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) B2ABEachpacket findsitswaythroughthenetworkbyusingitsdestinationadressIP Packet Switching # 20Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) B2ABEachpacket findsitswaythroughthenetworkbyusingitsdestinationadressIP Packet Switching # 21Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) B2ABEachpacket findsitswaythroughthenetworkbyusingitsdestinationadressIP Packet Switching # 22Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) B2ABEachpacket findsitswaythroughthenetworkbyusingitsdestinationadressIP Packet Switching # 23Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) B2ABB1And thus, latencymayvary…Eachpacket cantakea different route…Thereisnofixedconnectionanymore…IP Packet Switching # 25Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) •Underlying network technologyLatency –determining factorsNetwork technologyNetwork speedFrame transmission time (MTU)FE100 Mbit/s258,58 µsGbE1 Gbit/s25,86 µs (~ 1 sample time @ 48 kHz)10G10 Gbit/s2,6 µs40G40 Gbit/s10,4 µs100G100 Gbit/s260 ns•Type of swi tchi ng / routi ng equi pmentoHardware / switching fabric (switches, most routers)oSoftware (some routers / firewalls etc.)oMixed (routers w/ firewalls and / or advanced processing / filtering functions)oStore-and-forward vs. cut-through # 26Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) •Network topology oNumber of hops §1 hop @ GbE / switched: ~ 1 sample time @ 48 kHz§4 hops @ FE / switched: ~ 1 msoUnfortunately: delay not static due to dynamic traffic situationLatency –determining factors # 27Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) •Network topology oNumber of hops oDistances (speed of light)Latency –determining factorsDistanceTime1 m3.3 ns1 km3.3 µs4000 km (NYC –LA)13.3 msto geostationary orbit119 msaround Earth's equator134 msMoon to Earth1.3 s # 28Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) •Network topology onumber of hops oDistances (speed of light)Latency –determining factorsDistanceTime1 m3.3 ns1 km3.3 µs6 km20 µs (1 sample @ 48 kHz)300 km1 ms(mandatoryAES67 packet time)4000 km (NYC –LA)13.3 msto geostationary orbit119 msaround Earth's equator134 msMoon to Earth1.3 s3x round-trip Earth -Neptun~ 1 d 51 m 19 s (RTP counterrollover@ 48 kHz) # 29Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) •Network jitter ("PDV –packet delay variation")Latency –determining factors123456Txpacket streamRxpacket streamNetwork transitdelay123456t # 30Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) •Network jitter ("PDV –packet delay variation")Latency –determining factors123456Txpacket streamRxpacket stream123456Network transitdelayNetwork jittert # 31Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) •Network jitter ("PDV –packet delay variation")oswitch performance (hardware / software) ohops / routing (routing may change àno. of hops may change, network speed may change between hops)obandwidth utilizationLatency –determining factors # 32Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) •Network jitter ("PDV –packet delay variation")oswitch performance (hardware / software) ohops / routing (routing may change àno. of hops may change, network speed may change in between)obandwidth utilization –without QoS:Latency –determining factors # 33Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) •Network jitter ("PDV –packet delay variation")oswitch performance (hardware / software) ohops / routing (routing may change àno. of hops may change, network speed may change in between)obandwidth utilization –with QoS:Latency –determining factors # 34Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) QoS–Differentiated Services (DiffServ) # 35Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) •Network jitter ("PDV –packet delay variation")oswitch performance (hardware / software) ohops / routing (routing may change àno. of hops may change, network speed may change in between)obandwidth utilization –with QoS:Latency –determining factorsCompetingtraffic!May causeoverflow! # 36Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) Bytes 100 1000 Mbit/s MTU RTP 1460 MTU IP 1472 98,70 987,03 Mbit/s MTU Ethernet 1500 Ethernet Frame Size 1518 123,04 12,30 µs Ethernet Frame Size w/ VLAN tag 1522 123,36 12,34 µs Preamble: 8 Interframe Gap: 12 Formula for max. Bridge Latency MaxLatency = t_BridgeDelay + t_MaxFrame + n * t_StreamFrame n= number of concurrent RTP streams from different ingress ports for same egress port t_BridgeDelay 10,24 1,024 µs max. BridgeLatency 258,58 25,86 µs n= 1 Max. Ethernet Frame Size 1522 Bytes Bytes Bytes 1. stream FE GbE FE GbE FE channels 8 8 8 bytes / sample 3 3 3 frames/packet 48 48 48 sample rate 48000 48000 48000 payload 1152 1152 1152 frame size 1214 1214 1214 frame + pre + IFG 1234 1234 1234 Worst Case Latency 1713,12 171,31 3426,24 342,62 5139,36 Competing streams number 15 15 15 channels 8 8 8 bytes / sample 3 3 3 frames/packet 48 48 48 sample rate 48000 48000 48000 payload 1152 1152 1152 Net Data Rate Ethernet Transfer Time 1. Hop Delay (µs) 2. Hop Delay (µs) 3. Hop Delay (µs) Latency –worst case multi-hop calculations # 37Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) Latency –determining factors•Stream / packet configuration & sampling rate # 38Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) …•Sampling rate: 48 kHz(optional: 44.1 / 88.2 / 96 kHz)•PCMbit width: 16 and 24 bits•# of channels per stream: 1..8……R4L4R3L3R2L2R1L1R1R2R3R4L1L2L3L4…Right channelCombinedstereoPCM dataLeftchannelAES67 –(mandatory) encoding parameter # 39Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) •Packet time: # of frames (samples x channels) per packet at given sample rateFrame 1Frame 2Frame 3…Sample 1Sample 2Sample 3…Channel 1Sample 1Sample 2Sample 3…Channel 2Sample streamStream offramesFrame 1Frame 2Frame 3…Sample 1Sample 1Sample 1…Sample 2Sample 2Sample 2…Sample 3Sample 3Sample 3……Sample 1Sample 2Sample 3……………Channel n•Packet time:AES67 –(mandatory) encoding parameter # 40Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) Bytes per sample 3 MTU- RTP 1460 Freq 48000 Frames per packet 1 8 12 32 48 128 256 Latency ms 0, 02 0, 17 0, 25 0, 67 1, 00 2, 67 5, 33 Channels 1 3 24 36 96 144 384 768 per 2 6 48 72 192 288 768 1536 frame 3 9 72 108 288 432 1152 2304 4 12 96 144 384 576 1536 3072 5 15 120 180 480 720 1920 3840 6 18 144 216 576 864 2304 4608 7 21 168 252 672 1008 2688 5376 10 30 240 360 960 1440 3840 7680 Bytes per sample 3 MTU-RTP 1460 Freq 48000 Speed 1000 max. Load % 90 Frames per packet 1 8 32 48 64 128 256 Latency ms 0,02 0,17 0,67 1,00 1,33 2,67 5,33 max. channels 486 60 15 10 7 3 1 Channels 1 3 24 96 144 192 384 768 per 2 6 48 192 288 384 768 1536 frame 3 9 72 288 432 576 1152 2304 4 12 96 384 576 768 1536 3072 5 15 120 480 720 960 1920 3840 6 18 144 576 864 1152 2304 4608 7 21 168 672 1008 1344 2688 5376 64 192 1536 6144 9216 12288 24576 49152 = MTU size exceeded Channels 1 32,64 5,09 2,14 1,81 1,64 1,40 1,28 per 2 33,79 6,24 3,29 2,96 2,80 2,55 2,43 frame 3 34,94 7,39 4,44 4,11 3,95 3,70 3,58 4 36,10 8,54 5,59 5,26 5,10 4,85 4,73 5 37,25 9,70 6,74 6,42 6,25 6,01 5,88 6 38,40 10,85 7,90 7,57 7,40 7,16 7,04 7 39,55 12,00 9,05 8,72 8,56 8,31 8,19 64 105,22 77,66 74,71 74,38 74,22 73,97 73,85 Channels 1 27 176 421 497 547 643 705 per 2 26 144 273 304 321 352 370 frame 3 25 121 202 218 227 243 251 4 24 105 160 170 176 185 190 5 24 92 133 140 143 149 152 6 23 82 113 118 121 125 127 7 22 75 99 103 105 108 109 64 8 11 12 12 12 12 12 Packet size in bytes Bandwidth in Mbit/s Packetization Latency Streams per Link Latency –determining factors•Stream / packet configuration & sampling rate # 41Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) •Sender / receiver implementationoHardwareoEmbeddedoSoftware (VSC)Latency –determining factors # 42Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) •Fully self-contained RAVENNA implementation•Audio interfaces: I2S (8 ch) / TDM, MADI (64 ch)•Up to 192 kHz sampling rate•Lowest latency support: down to 1 sample/packet!•2 GbE NICs w/ ST2022-7 redundancy or load balancing•2x 64 channels in & out•Full AES/EBU bit-transparent operation supported•Jitter / delay buffer up to 40 msper channel•4-tier 256 x 256 audio matrix•Full AES67 & ST2110-30/-31 supportCOMi.MX –RAVENNA / AES67 SoM2x GbE8 chI2S64 ch TDM64 chMADI # 43Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) BACH Minuet System-on-a-ChipHighest performance SoC for small & medium channel applications•Up to 16 channels•8 audio streams•Cost-efficient for even the smallest 2 or 4-channel solutions•Fully AES67 and ST 2110 standards compliant•2022-7 glitch-less redundancy # 44Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) VSC –Virtual Sound Cards•Windows / MacOS / Linux•Up to 64 channels playback / record•Typ. processing latency: ~ 10 ms # 45Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) Latency –determining factorsBufferImage courtesy of Andy Rayner (Nevion)•Stream alignment # 46Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) àLink offset & receiver buffer sizeLatency –determining factors # 47Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) AES67 synchronization -link offset (latency)RTP timestampof(first) sample (in packet)Desiredplayouttime forsampleRTP offsetSDP (a=mediaclk:direct=<offset>)+- # 48Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) Latency –determining factors123456Txpacket streamRxpacket stream123456Network transitdelayNetwork jitteràLink offset & receiver buffer sizeRxplayout123456Max. network jitterAlignment offset(+ safetymargin)tLink offset(latency) # 50Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) Latency –determining factorsGlobal AES67over WAN Demo # 51Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) AWS VirginiaLausanneMittweidaOttawaAWS FrankfurtGrenobleGlobal AES67over WAN Demo•2 continents•4 sites•3 RAVENNApartners•AWS cloud•SRT codec # 53Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) •Synchronization works via GPS-synchronized local GMs (no need to transport PTP)•There is packet loss but this can managed via SRT•Latency ranged from 200 to 600 ms•Receivers need to have deep receive buffers or mechanisms to compensate for the network delay and PDVAES67 over WAN -lessionslearned # 54Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) •Underlying network technology •Network topology•Network jitter (PDV)•Stream / packet configuration (packet time)•Sender / receiver implementation •Stream alignmentLatency –determining factors (summary)Ta ke a w a y s : ðsub-millisecondslatency is achievableðreq’dreceiver buffer size depends on application•AES67 requires 3 ms, but recommends 20 msàLink offsetàReceiver buffer sizeReceiver buffersize≠ Link offset(latency) # 55Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) Questions? # 56Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) More information…www.ravenna-network.com/resourcesRAVENNA / AES67 / SMPTE ST 2110 Resources:ravenna@alcnetworx.dewww.aimsalliance.org (resources) # 57Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) Contact information:www.ravenna-network.comAndreas HildebrandALC NetworX GmbHravenna@alcnetworx.de12X # 58SupplementalSlides # 59Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) DistanceTime1 m3.3 ns1 km3.3 µs6 km20 µs (1 sample @ 48 kHz)300 km1 ms(mandatoryAES67 packet time)4000 km (NYC –LA)13.3 msto geostationary orbit119 msaround Earth's equator134 msMoon to Earth1.3 s3x round-trip Earth -Neptun~ 1 d 51 m 19 s (RTP counterrollover@ 48 kHz)Proxima Centauri (nearest star)4.2 yearsacross the Milky Way100000yearsAndromeda Galaxy (nearest galaxy)2.5 million yearsApproximate light signal travel times # 60Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) # 61Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) RTP headerRTP payloadRTP Packets (Layer 5)•A format-agnostic transport protocol for real-time media data (RFC 3550)•Consists of an RTP header and a payload area # 62Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) RTP Packets (Layer 5)•A format-agnostic transport protocol for real-time media data (RFC 3550)•Consists of an RTP header and a payload area•RTP header (overhead) = 12 Bytes•IP + UDP + RTP overhead = 20 + 8 + 12 = 40 Bytes•MTU (maximum transmission unit, largest size of a packet that can be transmitted without being split): 1500 Bytes in an IP/Ethernet LANð0 to 1460 bytes available for RTPpayload dataper packet # 63Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) TrailerEthernet PayloadLayered Packet Encapsulation1518 / 1522Bytes14601282014/1841500 # 64Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) TrailerIP PayloadLayered Packet Encapsulation1518 / 1522Bytes14601282014/1841480 # 65Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) TrailerUDP PayloadLayered Packet Encapsulation1518 / 1522Bytes14601282014/1841472 # 66Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) Layered Packet Encapsulation1518 / 152214601282014/184TrailerBytes # 67Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) RTP -Layered Packet EncapsulationAudio Data (0..1460 bytes) # 68Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) RTP Packets -Payload•Consist of RTP header, optional payload headers and the payload itself•RTP overhead = 12 Bytes•IP + UDP + RTP overhead = 20 + 8 + 12 = 40 Bytes•MTU (maximum transmission unit, largest size of a packet that can be transmitted without being split) 1500 Bytes in an IP/Ethernet LAN: in principle 0 to 1460 bytes available for RTP payloaddata per packet•Examples: #1: 16 bit PCM, 2 channels, 96 samples (2 ms@ 48kHz): 384 bytes#2: 24 bit PCM, 8 channels, 48 samples (500 µs @ 96kHz): 1152 bytes#3: AES3 24 Bit PCM, 64 channels, 5 samples (104 µs @ 48 kHz): 1280 bytes # 69Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) AES67 technology components:•Network: IPv4 (IPv6), unicast / multicast & IGMPv2•Tra n s p o r t: RTP/AVP (RFC 3550 & 3551) / UDP / IP •Quality of Service: DiffServw/ 3 suggested traffic classes (DSCP) # 70Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) Quality of ServiceLunch?Coffee? # 71Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) QoS–Differentiated Services (DiffServ)•Defined in RFC 2474 •Defines up to 64 traffic classes (i.e. EF, AFx, CSx, BE etc.)•Packets are tagged with DSCP value (0 –63) # 72Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) Audio Data (0..1460 bytes)QoS–Differentiated Services (DiffServ)To S= DSCP (6 bits) # 73Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) CS6CS6EFEFAFAFBEBEBEBEBECS6QoS–Differentiated Services (DiffServ)CS6CS6BEAFAFEFEFBEBEBECS6 = q1EF = q2AF = q2BE = q3 # 74Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) QoS–Differentiated Services (DiffServ)•Defined in RFC 2474 •Defines up to 64 traffic classes (i.e. EF, AFx, CSx, BE etc.)•Packets are tagged with DSCP value (0 –63)•Switches store packets in different priority queues (requires proper configuration) # 75Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) CS6CS6EFEFAFAFBEBEBEBEBECS6QoS–Differentiated Services (DiffServ)CS6CS6BEAFAFEFEFBEBEBECS6 = q1EF = q2AF = q2BE = q3Queue 1 (High Priority)Queue 2 (Medium Priority)Queue 3 (Low Priority) # 76Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) CS6CS6EFEFAFAFBEBEBEBEBECS6QoS–Differentiated Services (DiffServ)CS6CS6BEAFAFEFEFBEBEBECS6 = q1EF = q2AF = q2BE = q3 # 77Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) QoS–Differentiated Services (DiffServ)•Defined in RFC 2474 •Defines up to 64 traffic classes (i.e. EF, AFx, CSx, BE etc.)•Packets are tagged with DSCP value (0 –63)•Switches store packets in different priority queues (requires proper configuration)•Egress scheduler forwards packets from higher prioritized queues first (strict priority / weighted round robin / guaranteed minimum bandwidth …) # 78Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) CS6CS6EFEFAFAFBEBEBEBEBECS6QoS–Differentiated Services (DiffServ)CS6CS6BEAFAFEFEFBEBEBECS6 = q1EF = q2AF = q2BE = q3 # 79Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) CS6CS6EFEFAFAFBEBEBEBEBECS6QoS–Differentiated Services (DiffServ)CS6CS6BEAFAFEFEFBEBEBECS6 = q1EF = q2AF = q2BE = q3 # 80Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) CS6CS6EFEFAFAFBEBEBEBEBECS6QoS–Differentiated Services (DiffServ)CS6CS6BEAFAFEFEFBEBEBECS6 = q1EF = q2AF = q2BE = q3AF # 81Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) QoS–Differentiated Services (DiffServ) # 82Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) QoS–Differentiated Services (DiffServ)•Defined in RFC 2474 •Defines up to 64 traffic classes (i.e. EF, AFx, CSx, BE etc.)•Packets are tagged with DSCP value (0 –63)•Switches store packets in different priority queues (requires proper configuration)•Egress scheduler forwards packets from higher prioritized queues first (strict priority, weighted round robin, guaranteed minimum bandwidth)•Needs to be supported along full path from the transmitting to the receiving end•No admission control àcongestion / packet dropping possible when bandwidth is exceeded # 83Latency in AoIPSystemsLatency in AoIPSystems –A. Hildebrand (ALC NetworX) AES67 synchronization -link offset (latency)RTP timestampof(first) sample (in packet)Desiredplayouttime forsampleRTP offsetSDP (a=mediaclk:direct=<offset>)+- # 84AES standardforaudioapplicationsof networks-High-performance streaming audio-over-IP interoperabilityAES67# 84© ALC NetworX GmbH 2022Production Workflow TimingBufferImage courtesy of Andy Rayner (Nevion)