Raj JainThe Ohio State University1ATMATMSignalingSignalingRaj JainProfessor of Computer and Information ScienceThe Ohio State UniversityColumbus, OH [email protected]://www.cis.ohio-state.edu/~jain/Raj JainThe Ohio State University2q Call Endpoints: Address Formatsq Call setup/releaseq Traffic Contract: Bandwidth, Quality of Serviceq Signaling Mechanisms: Message formatsOverviewRaj JainThe Ohio State University3Signaling StandardsSignaling Standardsq Q.931 = Basic Call Control for ISDNq Q.932 = Extends/uses Q.931 for supplementaryservices (call forwarding, etc)q Q.933 = Q.931 Extension/subset for Frame-relayq Digital Subscriber Signaling System 1 (DSS1)= Call control signaling over the D channel= Q.931 + Q.932 + lower layersq Signaling System 7 (SS7) deals with inside thenetwork while DSS1 deals with outside.q Q.2931 = Q.93B = Basic Call Control for B-ISDNRaj JainThe Ohio State University4Signaling ChannelsSignaling Channelsq Reserved VPI/VCIm x/1 = Meta-signalingm x/2 = Broadcast signaling (not used initially)m 0/5 = ATM endpoint to local network signalingboth point-to-point and point-to-multipointsignalingm x/5 = point-to-point signaling with other endpointsand other networksRaj JainThe Ohio State University5Meta-SignalingMeta-Signalingq Used to setup signaling channelsq All meta-signaling messages are one cell longand have VPI/VCI = 0/1q Sets up 3 types of signaling channels:m Point-to-pointm General broadcastm Selective broadcastq Procedures to:m Set up new signaling channelsm Release channelsm Verify channelsRaj JainThe Ohio State University6ATM AddressesATM Addressesq ATM Forum specifies three NSAP-like addressformats: DCC ATM Format, ICD ATM Format, E.164ATM Format. NSAP = Network Service Access PointAFIEnd SystemID (6B)High-Order DSP (10B)Selector(1B)Data CountryCode (2B)E.164 Number (8 B)39End SystemID (6B)Selector (1B)International Code Designator (2B)47End SystemID (6B)Selector (1B)45End System SuppliedNot Usedin RoutingNetwork suppliedDomain Specific Part (DSP)High-Order DSP (4B)High-Order DSP (10B)Initial Domain IdRaj JainThe Ohio State University7AddressingAddressingq Authority and Format Identifier (AFI)39 = ISO DCC, 47 = British Standards InstituteICD, 45 = ITU ISDNq Initial Domain Identifier (IDI). Domain SpecificPart (DSP)q ISDN uses E.164 numbers (up to 15 BCD digits)q ATM forum extended E.164 addresses to NSAPformat. E.164 number is filled with leading zeros tomake 15 digits. A F16 is padded to make 8 bytes.AFI and DSP are added.Raj JainThe Ohio State University8Addressing (Cont)Addressing (Cont)q End System Identifier (ESI): 48-bit IEEE MACaddress.q Selector is for use inside the host and is not used forrouting.q All ATM addresses are 20 bytes long.q ATM forum removed the division of DSP into areas,etc.q Private networks must support all three formatsType of Number field = UnknownNumbering Plan Indication field = ISO NSAPRaj JainThe Ohio State University9Addressing (Cont)Addressing (Cont)q Public networks must support native E.164 and mayoptionally support three NSAP-encoded formats. ForE.164:Type of Number field = International numberNumbering Plan Indication field = RecommendationE.164q If only native E.164 addresses, subaddress field insignaling messages used to convey private ATMaddress across.q One Transit network selection possible using carrieridentification code field.Raj JainThe Ohio State University10NSAP is a Misnomer!NSAP is a Misnomer!q NSAP = Network Service Access Point. Identifiesnetwork layer service entryq SNPA = Subnetwork point of attachment. Identifiesthe interface to subnetworkq SNPA address (or part of it) is used to carry thepacket across the network.q CLNP uses NSAP to deliver thepacket to the right entity in the host.q ATM uses NSAP-like encodingbut ATM addresses identifySNPA and not NSAP.NetworkDatalinkPhysicalSNPANSAPRaj JainThe Ohio State University11Address RegistrationAddress Registrationq User and switch register addresses usingInterim Local Management Interface (ILMI)= Simple Network Management Protocol (SNMP)User SwitchColdStart TrapInitializeGetNext RequestWhat is your address?GetNext ResponseMy address is AA-...Set RequestUse prefix +1 614-...ResponseSure. Will do.q Similar activities can occur in the reverse direction.Raj JainThe Ohio State University12Connection TypesConnection Typesq Permanent and Switchedq Point to pointm Symmetric or asymmetric bandwidth (Uni- or bi-directional)q Point-to-multipoint: Data flow in one direction only.Data replicated by network.m Leaf Initiated Join (LIJ) or non-LIJRaj JainThe Ohio State University13Connection SetupConnection SetupSetupCall ProceedingSetupCall ProceedingConnectConnect AckConnectConnect AckConnectConnect AckReleaseRelease CompleteSetupCall ProceedingAcceptRejectRaj JainThe Ohio State University14Connection ReleaseConnection ReleaseReleaseRelease completeReleaseReleaseRelease completeRelease completeReleaseRelease completeRelease completeRelease completeReleaseReleaseOrRaj JainThe Ohio State University15Connection Release (Connection Release (contcont))ReleaseRelease completeRelease completeReleaseConnectionTerminatedRaj JainThe Ohio State University16Multipoint SetupMultipoint SetupSetupCall ProceedingSetupCall ProceedingConnectConnect AckConnectConnect AckConnectConnect AckSetupCall Proceeding221. Connect to the first party11Raj JainThe Ohio State University17Multipoint Setup (Cont)Multipoint Setup (Cont)Add PartyAdd PartyConnectConnect AckAdd Party AckAdd Party AckSetupCallProceeding222. Add the next party. The party accepts.11Raj JainThe Ohio State University18Multipoint Setup (Cont)Multipoint Setup (Cont)Add PartyAdd PartyReleaseReleaseCompleteAdd Party RejectAdd Party RejectSetupCallProceeding223. Add the next party. The party Rejects.11Raj JainThe Ohio State University19Multipoint Multipoint ConnConn. Release. ReleaseDrop PartyDrop Party AckDrop PartyDrop Party AckReleaseRelease complete221. Root Drops a party11ReleaseRelease completeReleaseRelease completeReleaseRelease complete2. Root Drops the last partyRaj JainThe Ohio State University20Multipoint Release (Cont)Multipoint Release (Cont)2211ReleaseRelease completeDrop Party AckDrop Party ackDrop PartyDrop Party3. A party drops outReleaseRelease completeRelease completeReleaseConnectionTerminatedDrop Party4. Network clears the callRaj JainThe Ohio State University21Leaf Initiated Join (LIJ)Leaf Initiated Join (LIJ)SetupCall ProceedingSetupCall ProceedingConnectConnect AckConnectConnect