ADTRAN Total Access 5000 - TWAMP Provisioning; TWAMP Connection Setup; TWAMP Test Session Setup; TWAMP Overview

Total Access 5000 Business Services Deployment Guide
D-2 65K510DEP08-1A
TWAMP Overview
TWAMPisamechanismbywhichIPperformancemetricsandpacketlosscanbeobtained
acrosstheMetroEthernet.Thesetypesofmetricsverifythatacertainservicelevelisbeing met
acrossthenetworkthatwasagreeduponbetweenthecustomerandtheserviceprovider.
TWAMPallowsaunitin
theMetroEthernettosetupand sendIP packetstoadestinationunit
intheMetroEthernet.Thedestinationunitreceivesthepacketandtransmitsitrightbackto
thesendingunit.Thepacketcontainstimestampsinsertedbythesendinganddestination
unitsthatindicatesendingtime,timereceivedand
re‐transmittedat thedestination unit,and
thetimereceivedbackatthesendingunit.Withthisinformation,thesendingunitcan
calculatethefollowingstatistics:packetloss,two‐wayla tency,anddirectional/one‐wayjitter.
NOTE
TheNCTEonlysupportsreflectormode.
TWAMP Provisioning
InTWAMPterminology,thesourcenodeorsenderiscalledtheʺses si o n ‐senderʺandthe
reflectorissimplycalledtheʺses si o n ‐reflectorʺ.Inaddition,thesourcenodeusuallyhasthe
responsibilityofinitiallyrequestingaTWAMPsessiontocommence.InTWAMPterminology
thisiscalledtheʺControl‐Clientʺ‐sometimesjust
abbreviatedtoclient.Thereflectornode
alsohasanotherroleofbeingtheTWAMPʺserverʺ.Theʺserverʺisresponsibleforaccepting
theTWAMPrequestsfromthesourcenode.
TheTWAMPprotocolcanbedividedupintothe4logicalstates.Eachphasecommences
sequentiallyintimeinanormalTWAMP
probeexchange:
•Theconnectionsetupphase(runoverTCP)
•Thetestsessionsetupphase(runoverTCP)
•Theactivetestsessionphase(runoverUDP)
•Thetestsessionendandpmretrievalphase(runoverTCP)
NOTE
Theactivetestse ssion phaserunsoverUDP,whereastheother3phasesall
runoverasingleTCPconnection.
TWAMP Connection Setup
Thehostthatinitiatesthetcpconnectiontakestheroleofcontrol‐clientandsessionsender.
ThehostthatacknowledgestheTCPconnectionisthesession‐reflector.
TWAMP Test Session Setup
Thesession‐reflectordoesNOTprocessincomingtestpacketsforPMmetricsanddoesnot
careaboutthesendschedule.Consequently,thenumberofscheduledslotsandnumberof
packetsintherequest‐sessioncommandmustbesetto0.
SenderUDPportistheUDPportusedforsendertransmission.
ReceiverUDPportistheUDP
portusedforreflectortransmission.