Through the ITU of standard the corresponding relations of SS7 are similar as OSI Seven-layer Architecture of data networking, including MTP(Message Transfer Part) , SCCP, TCAP , INAP,OMAP,MAP, ISUP , TUP .
There are 3 MPT has assigned for communicating, including MTP 1 , MPT 2, MTP 3, The signaling data link layer of MTP1 match with Physical layer of OSI , the signaling data link layer of MTP2 matchs with Datalink layer of OSI, the signaling data link layer of MTP3 matchs with Network layer of OSI.The SCCP part matchs with Transfer layer, TCAP matchs with Session layer and Presentation layer. About the INAP, OMAP, MAP , ISUP , TUP are matched with Application layer of OSI.
MTP1、2、3 protocol
-Signaling network functions of MTP3 :
MTP3: implement the functions of the
network layer of the OSI reference model, and is used to enable management
message transmission between the signaling points for the purpose of ensuring a
reliable transfer of the signaling messages over the signaling network in case
that signaling links and signaling transfer points fail 。
-Signaling network functions of MTP2 :
MTP2 is
used to transfer signaling to a data link. The level 2 functions together with
a level 1 signaling data link provide a signaling link for reliable signaling
transfer between two directly associated signaling points; MTP2 can provide
signal unit delimitation, signal unit alignment, error detection, error
correction, initial alignment, processor outage, level 2 flow control and
signaling link error monitoring
-Signaling data link MTP1 :
MTP1 is equivalent to the physical layer of
the OSI reference model and is used to generate and receive the signals through
the physical channels. It defines the physical, electrical and functional
characteristics of a signaling data link and the means to access it.
ISUP and TUP
ISUP (ISDN User Part ):
-It defines the signaling messages,
functions and procedures required to control voice and non-voice services (for
example, circuit switched data communication). The ISUP can not only implement
the functions of the Telephone User Part (TUP) and the Data User Part (DUP),
but also achieve the ISDN services on a wide basis, thus having a spacious
application scope
TUP (Telephone
User Part
)
-
The TUP function is similar to ISUP, but can not support data type
applications
SCCP protocol
SCCP protocol (Signaling Connection
Control Part ):
-SCCP is one of the user parts in
the hierarchical architecture of the Signaling System No. 7, and resident at
the functional level 4.
-The SCCP provides additional functions to the Message
Transfer Part (MTP) to cater for both connectionless as well as
connection-oriented network services to transfer circuit related and
non-circuit related signaling information and other types of information
between exchanges and specialized centers in telecommunication networks through
a SS7 network
MAP protocol
MAP protocol (Mobile Application Part ):
-MAP defines how information is
exchanged between mobile system communication network entities for the purpose
of achieving Mobile Station (MS) roaming function .
MAP can support location update,
authentication, encryption, hand over functions for MS
CAP protocol
CAP (CAMEL Application Part ):
CAP is from INAP, and it is used
for the IN services
CAP enables signaling interworking
between GSM Service Switching Function (gsmSSF), GSM Specialized Resource Function (gsmSRF) and GSM Service Control Function
(gsmSCF) of radio IN functional entities,
for the purpose of supporting CAMEL services
