Name: ADTRAN Total Access 5000
Brand: ADTRAN
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Total Access 5000 Business Services Deployment Guide

6-12 65K510DEP08-1A

EFM Bonding Overhead Description

Beforebeingtransportedoverthephysicallayer(DS3,T1,etc.),theEFMbondingenginefirst

encapsulatesEthernetframesintoEFMfragments.EFMFragmentpayloadscanvaryfrom64

to512bytesdependingontheEthernetpacketsize.IfanEthernetFrameis512bytesor

smaller,itisplacedintoone

EFMfragment.Iftheframeisbetween513and1024bytes,itis

splitbetweentwoEFMfragments.Iftheframeis1025bytes orgreater,itissplitbetweenthree

EFMfragments.

EachEFMfragmenthasthefollowingoverhead:

•Thereare2bytesofoverheadperfragmentthatarethe

sameforallfragments: astartbyte 

andCkbyte(anEOFdesignator)

•Theframechecksequence(FCS):Thesizeofthisdependsontechnology

•Thereare2additionaloverheadbondingheaderbytes

ForDS3,thiscomesoutto8overheadbytesperfragment.Inaddition,aspartofthe64/65

EFM

framing,therearecodewordsthatare64payloadbytesand1syncbyte.

Usingthisinformation,thefo llowingequationscanbeusedtodeterminetheeffective

percentageoftheEFMbondinggroupthatisavailableforcustomerEthernettransport(for

DS3):

•Ethernetframes512bytesorsmaller:

%Utilization=(Frame

Size)/(FrameSize+8)x(64/65)

•Ethernetframesbetween513and1024bytes,inclusive:

%Utilization=(FrameSize)/(FrameSize+16)x(64/65)

•Ethernetframes1025bytesorlarger:

%Utilization=(FrameSize)/(FrameSize+24)x(64/65)

TheequationsaboveassumethattheNetVanta

isnotaddinganextratagtothecustomer

traffic(ie.whenthecustomertrafficistagged,andthecustomeredgetagisnotbeing

preserved).Inanycasewherethecustomertagispreserve d(themostlikelyscenario),andthe

NetVanta800issimplystackingtheprovisionedserviceprovidertag

(s‐tag)tothecustomer

tag(ifpresent),thecalculationmustaccountfortheadditional4bytesforthes‐tag,asfollows:

•ForEthernetframes512bytesorsmaller:

%Utilization=(FrameSize)/(FrameSize+12)x(64/65)

•ForEthernetframesbetween513and1024bytes,inclusive:

%

Utilization=(FrameSize)/(FrameSize+20)x(64/65)

•Ethernetframes1025bytesorlarger:

%Utilization=(FrameSize)/(FrameSize+28)x(64/65)

TodeterminetheEFMbondinggroupbandwidththatneedstobeprovisionedsothatthe

customerʹscommissionedrateisprovided,dividethe

customerratebythispercentage:

RequiredEFMGroupRate=(CustomerCommissionedRate)/(%Utilization.

Followingareexamplecalculationsforcustomerthroughputpercentage,givenafixedframe

size,assumingtheNetVanta800isaddingaVLANtag:

•For64byteEthernetframes(worstcasescenario):

%Utilization=(64)/(64

+12)x(64/65)=82.9%

•Foran8Mbpsbondinggroup,theactualthroughputwouldbe:

8Mbpsx.829=6.632Mbps

•Ifacustomerissolda4Mbpsservice,therequiredEFMgroupsizecalculationwouldbe:

(4Mbps)/(.829)=4.825Mbps

ADTRAN Total Access 5000 Specifications

Interfaces

craft interface	DB-9 RS-232 Electrical Interface (Async)
admin interface	DB-9 RS-232 DTE Electrical Interface (Async with Modem Control Signals)
network management port	DB-9 RS-232 DTE Electrical Interface (Async)
ethernet interface	10Bt
external alarm inputs	16

Operating Environment