Bandwidth,Inter-SwitchLinksAndLargerNetworks - Calrec TYPE R Installation Manual

Bandwidth,Inter-SwitchLinksandLargerNetworks

Networktopologyandbandwidthmanagementareimpactednotjustbythequantity,butalsobythephysicallocationofdevices.
EachcopperEthernetcableshouldbelessthan100mtotallength(factoringincableroutingandlooming,sooften90misquoted).
FibreSFPportsoradditionalswitchhopsneedtobeusedtoextendtherangebeyond100m.
Whereswitchesareconnectedtogether,oneshouldbemindfulofthebandwidthavailableontheinter-switchlinks.
Multiplelinkscanbefittedbetweenswitchesastrunkstoincreasebandwidth(switchesneedtobeappropriatelyconfiguredto
supportsuchconnectionsusingLACPlinkaggregation),andmanyswitcheshaveapairormoreofSFPslotsthatarecapableof
higherbandwidth,intendedtobeusedtoconnecttootherswitches.
Onthe10(8+2)portQuarraswitchesthatCalreccurrentlyuse,2oftheportsareSFPslotsthatcanbefittedwitheither1Gbpsor
2.5GbpsSFPinterfaces.NotethatswitchesarenotsuppliedwiththeSFPinterfaces.
AsageneralruleofthumbforAoIP,audiotrafficshouldnotexceedroughly50%ofthecapacityonalink.
Thisbroadlyequatesto256channelsofaudioovera1Gbpslink.Thisisasomewhatconservativeguideline,butitisasafe
recommendationforcriticalliveaudioapplicationsuchasbroadcast.
Audioisnottheonlydatabeingpassed,evenonadedicatedaudionetworkthereisstilladditionaltraffic.Higherchannelcountscan
beachieved,butdeterministicnetworkconditionsarerequiredtosuccessfullyexceedthesafeworkingrecommendations.
TypeRCorescanpassupto256audiochannelsovereachAoIPInterfacecard.
Using32x8channelstreams(at32bit/48kHz/125uspackettime),thebandwidthconsumptionofaudioforeachportwouldbe
554Mbps.With2cardsfitted,theoverallaudioconsumptionofaTypeRcorecanpotentiallybemorethan1Gbps
Iflargeamountsofaudio/datahavetopassoveragivennetworksegmentsuchasaninter-switchlink,thenhigherbandwidthSFPs
shouldbeusedforthosesegments(ormultipleaggregatedlinks).
TypeRI/OboxeshaveasingleredundantpairofAoIPports,capableofpassingupto64channelsofaudio.
AsthelargestTypeRI/Oboxesonlyhave16channelsofphysicalaudioI/Oports,typicalactualusagewouldbeonly35Mbps.
Ifrequired,audiobandwidthcanbereducedbyusinga1mspackettime(atthecostofincreasedlatency),orbyusing24bitaudio
(sacrificingtheadditionalheadroomweprovideforourmicinputs).
Forlargernetworkswithlotsofswitches,insteadofdaisy-chainingthemtogether,theyshouldconnectviaanadditionalswitch,as
showninExamples6,7,11,12and13,inordertolimitthenumberofswitchesthatdatahastopassthroughtogetfrompointAto
pointB,providingmoreuniformlatency,andmakingbandwidthsimplertomanage.
ThedottedlinesshowninExample6representtheoptiontoincreasebandwidthonswitchlinksthroughaggregationifneeded.
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