Ady Wicaksono Daily Activities

Compare TCP/IP – SS7 Protocol Stack based on OSI Layer

with 4 comments

I gave you an example of SS7 – GSM MAP log from my previous post about GSM – MAP. I will give you a picture of SS7 protocol stack and TCP/IP protocol stack so you could easily understand about SS7 if you understand TCP/IP or vice versa.

SS7

tcp-ip-protocol.png

You see that GSM MAP – Mobile Application Part actually is similar with HTTP, SMTP and many other application layer on TCP/IP.

However, if on TCP/IP many application layer use user friendly protocol, not with SS7. For example, on SMTP Protocol, basically it’s very clear that Client (C) communicate with Server (S) like this:

C: EHLO localhost

S: 250 SMTP adywicaksono is ready

C: MAIL FROM: <testuser@domain.com>

S: 250 OK

……. and so on

But in GSM-MAP, you just talking about signalling means talking about bit & byte like this:

tc7e0 f15 d2d s00 i001b r0000 p(189)

4517090007320807001010151809040797440000000019199e400a915413131215000070206091553200a0050003e10201363c180c0693ddc2b78d0f447dbbf320213b9c9683d0e139681e4e9341e8f41c647ecbcbe9b31b047fb3d3e33c283d0789c66f375dfeb697e5f374982d0289eb74103a3d0785e170f93b3c4683de66503bcd4ed3c3f23c28eda697e5f6b29b9e7ebb41edfa9c0e1abfddf4b4bb5e7681926e5018d40eabdf72d01c5e2e8fd12c10ba0c9a87d31a000e010100

Yes, not user friendly for us but very effective & efficient for machinešŸ™‚

Actually the meaning of this MAP protocol is like this:

MAP-MT-FORWARD-SHORT-MESSAGE-REQ

Parameter Key           :   23 (0x17) (Short message destination address (IMSI, LMSI, MS-ISDN roaming number or srv centre address))                                                                                                                                                                                                                  
Parameter Length        :    9 (0x9)                                                                                                                                                                                                                                                                                                                  
Parameter Value         : 000732080700101015                                                                                                                                                                                                                                                                                                          
Parameter Key           :   24 (0x18) (Short message originating address (MS-ISDN or srv centre address))                                                                                                                                                                                                                                             
Parameter Length        :    9 (0x9)                                                                                                                                                                                                                                                                                                                  
Parameter Value         : 040797440000000019                                                                                                                                                                                                                                                                                                          
Parameter Key           :   25 (0x19) (Short message user data field)                                                                                                                                                                                                                                                                                 
Parameter Length        :  158 (0x9e)                                                                                                                                                                                                                                                                                                                 
Parameter Value         : 400a915413131215000070206091553200a0050003e10201363c180c0693ddc2b78d0f447dbbf320213b9c9683d0e139681e4e9341e8f41c647ecbcbe9b31b047fb3d3e33c283d0789c66f375dfeb697e5f374982d0289eb74103a3d0785e170f93b3c4683de66503bcd4ed3c3f23c28eda697e5f6b29b9e7ebb41edfa9c0e1abfddf4b4bb5e7681926e5018d40eabdf72d01c5e2e8fd12c10ba0c9a87d3
Parameter Key           :   26 (0x1a) (Srv centre has more short messages to send)
Parameter Key           :   14 (0xe) (invoke id)
Parameter Length       :    1 (0x1)
Parameter Value         : 0x01

Well, Short message user data field itself is also very complex.Read GSM 03.40, please :))

Written by adywicaksono

July 16, 2007 at 3:51 pm

Posted in Telco - GSM

4 Responses

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  1. I think that the main reason why SS7 messages aren’t in user friendly format is that normally too few peoples work with SS7 directly. For all others whole GSM is hided under small box called mobile handset. Of course, normally users don’t send SMTP commands while need to submit emailšŸ™‚ but they have such ability! In GSM they don’t, so no needs to simplify the dialog.
    Anyway, I’m still dreaming about tool which will be able to create such HEX-coded SS7 messages using nice GUI… Did you see any? :))))

    No … you better create onešŸ˜€ hehehehe

    Bogdan

    October 31, 2007 at 9:33 am

  2. tcp/ip protocol

    sandeep

    August 17, 2009 at 6:09 pm

  3. Nicely captured.

    gigadom

    January 15, 2011 at 2:02 am


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