Raj JainThe Ohio State University1ATMATMSignalingSignalingRaj JainProfessor of Computer and Information ScienceThe Ohio State UniversityColumbus, OH [email protected] slides are available at:http://www.cis.ohio-state.edu/~jain/cis777-99/Raj JainThe Ohio State University2OverviewOverviewq Call Endpoints: Address Formatsq Call setup/releaseq Traffic Contract: Bandwidth, Quality of Serviceq Signaling Mechanisms: Message formatsRaj JainThe Ohio State University3Meta-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 University4ATM 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 University5AddressingAddressingq 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 University6Addressing (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 University7Addressing (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 University8NSAP 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 University9Address 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 University10Connection 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 University11Connection SetupConnection SetupSetupCall ProceedingSetupCall ProceedingConnectConnect AckConnectConnect AckConnectConnect AckReleaseRelease CompleteSetupCall ProceedingAcceptRejectRaj JainThe Ohio State University12Connection ReleaseConnection ReleaseReleaseRelease completeReleaseReleaseRelease completeRelease completeReleaseRelease completeRelease completeRelease completeReleaseReleaseOrRaj JainThe Ohio State University13Connection Release (Connection Release (contcont))ReleaseRelease completeRelease completeReleaseConnectionTerminatedRaj JainThe Ohio State University14Multipoint SetupMultipoint SetupSetupCall ProceedingSetupCall ProceedingConnectConnect AckConnectConnect AckConnectConnect AckSetupCall Proceeding221. Connect to the first party11Raj JainThe Ohio State University15Multipoint Setup (Cont)Multipoint Setup (Cont)Add PartyAdd PartyConnectConnect AckAdd Party AckAdd Party AckSetupCallProceeding222. Add the next party. The party accepts.11Raj JainThe Ohio State University16Multipoint Setup (Cont)Multipoint Setup (Cont)Add PartyAdd PartyReleaseReleaseCompleteAdd Party RejectAdd Party RejectSetupCallProceeding223. Add the next party. The party Rejects.11Raj JainThe Ohio State University17Message Format: Q.2931Message Format: Q.2931Other Information ElementsProtocol Discriminator8 7 6 5 4 3 2 10000 Lenof Call RefFlagCall Reference ValueMessage TypeMessage (Content) LengthRaj JainThe Ohio State University18Message FormatMessage Formatq Protocol Discriminator (1 Byte) = DistinguishesQ.2931 messages from other messages08 = Q.931 09 = Q.2931q Call reference (4 bytes) : Identifies call to which thismessage is related to. One user may have many callssimultaneously.m Flag = 1 Message is from call reference originatorm Flag = 0 Message is to call reference originatorq Message Type (2 Bytes): Many types, e.g., connect,call proceeding, setup, release, etc.q Message Length (2 Bytes): Length of contentsRaj JainThe Ohio State University19Sample Message TypesSample Message TypesBits 876 Bits 54321 Type000 Call establishment messages00010 Call proceeding00111 Connect01111 Connect Ack00101 Setup01101 Setup Ack010 Call Clearing Messages01101 Release11010 Release complete011 Information10101 Status Inquiry11101 Status111 Reserved for extensionRaj JainThe Ohio State University20Information ElementInformation ElementFormatsFormatsInformation Element IdentifierCodingStandard Flag Res IE Action Ind1ExtLength of contents of IEContents of IEIE Instruction Field8 7 6 5 4 3 2 1123-45+Raj JainThe Ohio State University21Sample InformationSample InformationElementsElementsBits 87654321 Information Element01110000 Called party number01110001