Table of Contents
1DTE/DCEinterfacecharacteristics(physicallayer)
1.1X.21interface
1.2X.21bisinterface
1.3V-Seriesinterface
1.4X.31interface
2LinkaccessproceduresacrosstheDTE/DCEinterface
2.1Scopeandfieldofapplications
2.2Framingaspects
2.3LAPBelementsofprocedures
2.4DescriptionoftheLAPBprocedure
2.5MultiLinkProcedure(MLP)
(Subscription-timeselectableoption)
3DescriptionofthepacketlayerDTE/DCEinterface
3.1Logicalchannels
3.2Basicstructureofpackets
3.3Procedureforrestart
3.4Errorhandling
4Proceduresforvirtualcircuitservices
4.1Proceduresforvirtualcallservice
4.2Proceduresforpermanentvirtualcircuit
service
4.3Proceduresfordataandinterrupttransfer
4.4Proceduresforflowcontrol
4.5Effectsofclear,resetandrestart
proceduresonthetransferofpackets
4.6Effectsofthephysicallayerandthedata
linklayeronthepacketlayer
5Packetformats
5.1General
5.2Callset-upandclearingpackets
5.3Dataandinterruptpackets
5.4Flowcontrolandresetpackets
5.5Restartpackets
5.6Diagnosticpacket
5.7Packetsrequiredforoptionaluser
facilities
6Proceduresforoptionaluserfacilities
(packetlayer)
6.1TOA/NPIaddresssubscription
6.2Extendedandsuperextendedpacket
sequencenumberingfacilities
6.3D-bitmodification
6.4Packetretransmission
6.5Incomingcallsbarred
6.6Outgoingcallsbarred
6.7One-waylogicalchanneloutgoing
6.8One-waylogicalchannelincoming
6.9Non-standarddefaultpacketsizes
6.10Non-standarddefaultwindowsizes
6.11Defaultthroughputclassesassignment
6.12Flowcontrolparameternegotiation
6.13Throughputclassnegotiationfacilities
6.14Closedusergrouprelatedfacilities
6.15Bilateralclosedusergrouprelated
facilities
6.16Fastselect
6.17Fastselectacceptance
6.18Reversecharging
6.19Reversechargingacceptance
6.20Localchargingprevention
6.21Networkuseridentification(NUI)
relatedfacilities
6.22Charginginformation
6.23ROArelatedfacilities
6.24Huntgroup
6.25Callredirectionandcalldeflection
relatedfacilities
6.26Calledlineaddressmodifiednotification
6.27Transitdelayselectionandindication
6.28Alternativeaddressingrelatedfacilities
7Formatsforfacilityfields
7.1General
7.2Codingofthefacilitycodefields
7.3Codingofthefacilityparameterfields
AnnexA-Rangeoflogicalchannelsusedforvirtualcalls
andpermanentvirtualcircuits
AnnexB-PacketlayerDTE/DCEinterfacestatediagrams
B.1Symboldefinitionofthestatediagrams
B.2Orderdefinitionofthestatediagrams
AnnexC-ActionstakenbytheDCEonreceiptofpackets
inagivenstateofthepacketlayerDTE/DCE
interfaceasperceivedbytheDCE
AnnexD-PacketlayerDCEtime-outsandDTEtime-limits
D.1DCEtime-outs
D.2DTEtime-limits
AnnexE-CodingofX.25networkgenerateddiagnostic
fieldsinclear,resetandrestartindication,
anddiagnosticpackets
AnnexF-Subscription-timeoptionaluserfacilities
thatmaybeassociatedwithanetworkuser
identifierinconjunctionwiththeNUI
overridefacility
AnnexG-ITU-TspecifiedDTEfacilitiestosupportthe
OSINetworkserviceandotherpurposes
G.1Introduction
G.2Codingofthefacilitycodefields
G.3Codingofthefacilityparameterfield
AppendixI-Examplesofdatalinklayertransmittedbit
patternsbytheDCEandtheDTE
AppendixII-AnexplanationofhowthevaluesforN1in
2.4.9.5arederived
II.1DTEN1
II.2DCEN1
II.3GeneralDCEN1calculations
AppendixIII-Examplesofmultilinkresettingprocedure
III.1Introduction
III.2MLPresetinitiatedbyeithertheDCE
ortheDTE
III.3MLPresetinitiatedbyboththeDCE
andtheDTEsimultaneously
AppendixIV-Informationonaddressesincallset-up
andclearingpackets
IV.1Mainaddressandcomplementaryaddress
IV.2Addressesincallrequestpacket
IV.3Addressesinincomingcallpackets
IV.4Addressesincallacceptedpackets
IV.5Addressesincallconnectedpackets
IV.6Addressesinclearrequestpackets
IV.7Addressesinclearindicationpackets
IV.8Addressesinclearconfirmationpackets
IV.9Addressesincallredirectionandcall
deflectionrelatedfacilities
AppendixV-Guidelinesfortransmissionoverchannelswith
longroundtripdelayand/ortransmission
rateshigherthan64000bit/s
V.1Preamble
V.2Commonguidelines
V.3Guidelinesforchannelswithlongroundtrip
delaysoperatingat64000bit/s
V.4Guidelinesforcircuitswithlongroundtrip
delaysoperatingat1920kbit/s
AppendixVI-FormatforNUIparameterfield
AppendixVII-Examplesoftheuseofmulti-selective
rejectoption Abstract
This Recommendation gives the protocol to be used between a Data Terminal Equipment (DTE) and a Packet Switched Public Data Network (PSPDN), when the access is made by a dedicated circuit. When referring to the OSI model, three layers are described: the physical layer, the data link layer and the packet layer. The offered service is compliant with the OSI network service and permits the transmission of data without loss nor duplication. Th The access speeds and the throughputs may go up to 2 Mbit/s.
