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SCCP vs TCAP :Differences ??????

Viewing 15 posts - 1 through 15 (of 23 total)
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  • #38670 Reply
    Rakesh
    Guest

    In all SS7 documents SCCP is said to be the layer which takes care of the Non Circuit related signalling ,examples of which include the Communication between HLR & VLR, SSP & SCP et al . Howver TCAP is also said to be more or less catering to same functions. Can somebody please enumerate some very claer differentiators between SCCP & TCAP layers . Is TCAP just providing a medium for what is done by SCCP .Pl clear

    #38671 Reply
    Hari
    Guest

    Hello Rakesh,

    SCCP supported services in addition to MTP3 of OSI “Network layer” by supporting capability to transfer NSDU’s.

    MTP-3 supports messages delivered end-destination based on DPC, and using SIO (4-bits) to distribute messages with-in the local node.

    To this SCCP suppliments the capability of supporting Global Titles and SSN, where GTT can be used to identify a SS7-node globally and SSN to identify the specific application locally.

    supporting GTT by SCCP means, decoding GTT into DPC and SSN.

    Also, SCCP supports for class of communication Class 0 to 3, where 0 and 1 are connection-less ( like UDP) where in later one supports message sequencing capability.
    Class 2 and 3 support connection-oriented where in later one supports “Flow-Control”.

    TCAP exploits the capabilities of SCCP to support non-circuit signaling between two end-points ( SS7 TCAP based applications) by supporting remote-procedure execution on other node and providing facilities to transfer the results.

    For more on SCCP read ITU-T Recommendations Q.711 up to Q.716 and for TCAP refer to Q.771 to Q.774

    Hope this helps……..

    #38672 Reply
    Kumar
    Guest

    Dear Hari,

    SCCP Class 0& 1 Are for UDP ( MAP )
    SCCP Class 2& 3 Are for UDP ( BSSAP)

    What exactly is the difference in these two…?

    If I check protocal ANalyzer The message flow is similiar.

    What is the exact difference we can point out…?

    Rgds

    #38673 Reply
    Hari
    Guest

    hello Kumar,

    Please refer to following link
    http://www.ietf.org/proceedings/01aug/I-D/draft-ietf-sigtran-sua-07.txt

    and section: 1.4.2

    -Hope this helps

    #38674 Reply
    rakesh
    Guest

    I am still not clear as to the difference between the SCCP & TCAP. Could somebody give some example of an application where TCAP only can be used (not SCCP) & some application where only SCCP can be used (not TCAP) .
    I want to get it cleared whether TCAP is just an extension of SCCP or it is a separate entity altogether .
    Folks, please help me on this

    #38675 Reply
    New Guy
    Guest

    TCAP Runs Over SCCP.So if you have to use TCAP you have ot run it over SCCP Only.

    SCCP Without TCAP you can use for BSSAP / ISUP – ISDN Type.

    Rgds

    #38676 Reply
    Rakesh
    Guest

    basically comparing SCCP with TCAP!! wont make any sense

    we can compare SCCP with MTP
    For example
    MTP have the capabilty to send and receive the S.U from one end of the link to other end, vis-versa.
    But SCCP is end- end connection
    From a node in a local network to another node in the another remote network
    ok
    Now we back to SCCP and TCAP
    Actually SCCP is a transport medium for TCAP!! U can ask already MTP is there whats the need for SCCP??
    I will give u one example!
    TCAP core functionality is to enable the feature in the remote switch/SP/exchange and quering Toll free number application.
    In toll free number application ( 800)
    Prerequest: u should know abt how toll free number works!!
    In brief:
    If u dial a 800 number, the local SSP wont have intelligent to route directly, it as to be translated to a intelligent routing number,
    So it will query the home STP for retriving the actual routing number
    corresponding to this toll free number.
    STP will do the GTT and find in which network inturns in which (SCP and SSN) database the corresponding routing number is available.
    If home STP doesnt have this info it will pass on to next hierarcial STP and goes on still it gets the actual routing number.
    Once it gets the routing info.. from the SCP it pass back to the SSP which queried
    And from now home SSP will start to establish the call ..

    In this scenario
    SSP–>STP–>SCP and visversa
    Yes local SSP form a TCAP message with the toll free numeber attach the SCCP header and etc..
    the query messages are TCAP message
    how the message will travel??
    by means of SCCP
    so SCCP is a end- end transport medium for TCAP
    from this u can conclude that TCAP uses SCCP bcos it needs end to end transport protocol for retriving the routing number from the SCP which may be located any were in the large network,

    i hope u can get clear idea now..

    #38677 Reply
    Rakesh
    Guest

    basically comparing SCCP with TCAP!! wont make any sense

    we can compare SCCP with MTP
    For example
    MTP have the capabilty to send and receive the S.U from one end of the link to other end, vis-versa.
    But SCCP is end- end connection
    From a node in a local network to another node in the another remote network
    ok
    Now we back to SCCP and TCAP
    Actually SCCP is a transport medium for TCAP!! U can ask already MTP is there whats the need for SCCP??
    I will give u one example!
    TCAP core functionality is to enable the feature in the remote switch/SP/exchange and quering Toll free number application.
    In toll free number application ( 800)
    Prerequest: u should know abt how toll free number works!!
    In brief:
    If u dial a 800 number, the local SSP wont have intelligent to route directly, it as to be translated to a intelligent routing number,
    So it will query the home STP for retriving the actual routing number
    corresponding to this toll free number.
    STP will do the GTT and find in which network inturns in which (SCP and SSN) database the corresponding routing number is available.
    If home STP doesnt have this info it will pass on to next hierarcial STP and goes on still it gets the actual routing number.
    Once it gets the routing info.. from the SCP it pass back to the SSP which queried
    And from now home SSP will start to establish the call ..

    In this scenario
    SSP–>STP–>SCP and visversa
    Yes local SSP form a TCAP message with the toll free numeber attach the SCCP header and etc..
    the query messages are TCAP message
    how the message will travel??
    by means of SCCP
    so SCCP is a end- end transport medium for TCAP
    from this u can conclude that TCAP uses SCCP bcos it needs end to end transport protocol for retriving the routing number from the SCP which may be located any were in the large network,

    i hope u can get clear idea now..

    #38678 Reply
    Magi
    Guest

    hi rakesh
    if u have any doudt
    reply to this article

    #38679 Reply
    Magi
    Guest

    hi rakesh
    if u have any doudt
    reply to this article

    #38680 Reply
    Magi
    Guest

    hi rakesh
    if u have any doudt
    reply to this article

    #38681 Reply
    Hari
    Guest

    Rakesh,

    Could you please take some time and have a look at SS7 protocol architecture.

    I hope it will help you to know, what “New Guy” ment. Any way, if things are not clear, we will work together to resolve them………

    -Keep posting!!!!!
    Hari

    #38682 Reply
    hercules
    Guest

    first of all, I will show you a simple example, suppose you have two computer in the network, if you observe in the IP layer, you can find all the packaet is the same for they have same source and dest ip address, yet when you see it in the layer above, you will find two different packet the TCp and udp. maybe sccp is somewhat like ip, and the tcap is somewhat like the tcp.
    now let’s look at the sccp and tcap, suppose you can observe the ss7 message from a vlr to a hlr, if you observe them in the sccp level, you will find out that all the packet is the same, for the source and dest Gt is the same,you can not distinguish each packet. but when you observe them in the tcap level, you will see they are all different by the variable tcap id, what is more, if you catch a packet with a certain tcap id, you can also find some other tcap packets which have same tcap id. all these packets are delevered in sequence to work for an application for a certain subscriber.
    now we can see sccp works for the message transfer between network nodes, and tcap works for a special application defined by its rule.
    in one word, they are desined for different purpose.

    #38683 Reply
    MANISH
    Guest

    Now with all the discussions can we finally conclude that SCCP can be effectively used by TCAP only. Without TCAP the SCCP functionality cannot be used . Or in other words to really make use of the SCCP features we ought to have the TCAP layer essentially.
    NO SCCP FUNCTIONALITY WITHOUT TCAP .

    Am I right or wrong folks ??

    #38684 Reply
    hercules
    Guest

    the tcap can not work properly without the help of sccp,yet sccp can be used by other layer protocol.for example the omap.

    maybe you can say the sccp is the road, and the tcap is a kind of car that runs over it.

    yet there are also some other cars the run over it.

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