network protocols handbook.pdf

305Protocols GuideSS7 / C7 ProtocolProtocol StructureThe SS7 / C7 protocol suite covers all 7 layers of the OSI modelas shown in the following diagram:Layer 7Layers4,5,6Layer 3TCAPASPSCCPTUPISUPBISUPLevel 4Network Level 3Layer 2 Data Link MTP Level 3Layer 1 Physical Level 2Figure 2-28: SS7/C7 Protocol Suite ArchitectureSCCPTCAPTUPSignalling ConnectionControl PartTransaction CapabilitiesApplicationPartTelephone UserPartSCCP provides end-to-end routing.SCCP is required for routing TCAPmessages to their proper database.TCAP facilitates connection to anexternal databaseTUP is an analog protocol thatperforms basic telephone call connectand disconnect.Related protocolsASP, BICC, BISUP, DUP, ISUP, MTP, SCCP, TCAP, TUP, MAPSponsor SourceSS7 / C7 protocols are defined by ITU-T in Q.700 documentsseries.ReferenceASPBICCApplication ServicePartBearer IndependentCall ControlprotocolASP provides the functions of Layers4 through 6 of the OSI model.BICC is a call control protocol basedon ISUP used between servingnodes to support the ISDN servicesindependent of the bearer technologyand signalling message transporttechnology used.http://www.cisco.com/univercd/cc/td/doc/product/tel_pswt/vco_prod/ss7_fund/SS7 Fundamentalshttp://www.itu.int/rec/recommendation.asp?type=folders&lang=e&parent=T-REC-Q.700Introduction to Signaling System No. 7BISUPB-ISDN User PartBISUP is an ATM protocol intended tosupport services such as high-definitiontelevision (HDTV), multilingual TV,voice and image storage and retrieval,video conferencing, high-speed LANsand multimedia.DUPData User PartDUP defines the necessary callcontrol, and facility registration andcancellation related elements for internationalcommon channel signallingby use of SS7 for circuit-switched datatransmission services.ISUPISDN User PartISUP supports basic telephone callconnect/disconnect between endoffices. ISUP was derived from TUP,but supports ISDN and intelligentnetworking functions. ISUP also linksthe cellular and PCS network to thePSTN.MAPMobile ApplicationPartMAP is used to share cellular subscriberinformation among differentnetworks.MTPMessage TransferPartMTP crosses physical, data linkand network layers. It defines whatinterface to be used, provides thenetwork with sequenced delivery of allSS7 message packets; and providesrouting, message discrimination andmessage distribution functions.