1 / 33

Signaling System 7 (SS7)

Signaling System 7 (SS7). Dr. Adeel Akram Telecommunication Engineering Department UET Taxila. Lecture Overview. Signaling System Signaling Environments Types of Signaling SS7 Signaling History of SS7 Introduction to SS7 PTN PSTN SS7 Network Elements SS7 Network SS7 Protocol Stack.

takara
Download Presentation

Signaling System 7 (SS7)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Signaling System 7 (SS7) Dr. Adeel Akram Telecommunication Engineering Department UET Taxila

  2. Lecture Overview • Signaling System • Signaling Environments • Types of Signaling • SS7 Signaling • History of SS7 • Introduction to SS7 • PTN • PSTN • SS7 Network Elements • SS7 Network • SS7 Protocol Stack

  3. Signaling System • It is a system which allows various network components to exchange information • In particular, it supports • call / connection control • network management

  4. Signaling Environments • Subscriber Signaling • Applied on Access Links • Tends to be only Call Control • Relatively Simple • e.g. DSS1 in ISDN • Network Signaling • In the network • Call Control and Network Control • Complex • e.g Signaling System 7 (SS7)

  5. Types of Signaling • Types of signaling • In-band signaling • signaling messages carried in same channel as user information • e.g. • TCP/IP • Analogue access links in telephone networks • Out-band signaling • Separate signaling channel for signaling messages • e.g. • ISDN access links • SS7

  6. Types of Signaling (contd.) • Within out-band signaling another distinction can be made: • Channel Associated Signaling (CAS) • Direct relationship between the signaling channel and information channel • Common channel signaling (CCS) • Signaling channel is shared on a demand basis

  7. Types of Signaling (contd.) • Modern signaling systems use out-band CCS • More secure (main reason why out-band signaling developed) • Signaling can be carried out at the same time as user information is exchanged • More efficient use of resources - allocated on a demand basis • Separate signaling network means less processing on messages - no need to separate signaling from user information • Signaling protocol can evolve independently, without effecting user application communication stack, can also be more complex. • At call set-up, signaling messages can be transmitted in parallel with the establishment of information channel (Not possible with CAS) • set-up times tend to be shorter

  8. Types of Signaling (contd.) • In CCS, signaling network is a separate network • Two modes of operation are possible with CCS • Associated mode • Same topology as information network • Signaling switches located with information switches • Non Associated mode • Combined signaling / information switches • Also, separate signaling switches called Signaling Transfer Points (STPs) • Result is a separate signaling network topology, with links and interfaces into underlying information network

  9. Types of Signaling (contd.) • Two signaling standards which operate at different levels: • Subscriber signaling • e.g. Digital subscriber system 1 (DS1) • Network signaling • Signaling System 7 (SS7)

  10. SS7 Signaling • Concerned with connection set-up and network management • Defined in Q700 series • Network components are • Signaling Points • Process signaling messages • Signaling Transfer Points • SPs with switching facilities • Signaling links

  11. History of SS7 • The SS7 protocols were developed by AT&T in 1975 • Replaces SS5 and SS6 in the United States. • SS6 was introduced in the mid 1960s. • It was the first widely used, high speed (2400 bps), digital, packet switched network. • Many people consider this to be the first packet switched network. • SS7 overcomes the security problems of SS5 • Called CCS7 /CCISS7 in the rest of the world. • Common Channel Interoffice Signaling System Number Seven

  12. Introduction to SS7 • In-band & Out-band

  13. PTN Securing SS7 Telecommunications Networks - http://www.itoc.usma.edu

  14. PSTN • World's public circuit-switched telephone networks • The Internet is the concentration of the world's public IP-based packet-switched networks • Originally a network of fixed-line analog telephone systems, the PSTN is now almost entirely digital

  15. PSTN Securing SS7 Telecommunications Networks - http://www.itoc.usma.edu

  16. SS7 Network Elements • SSP (Service Switching Point) • Service Switching Points (SSP) are switches that originate, terminate, or exchange calls • An SSP sends signaling messages to other SSPs • Allows querying of SCP (Service Control Point) • STP (Signal Transfer Point) • Provides Routing SS7 messages • Deployed in pairs • Three levels of STPs • National • International • Gateway

  17. SS7 Network Elements • SCP (Service Control Point) • Interface to a database • It is always connected to the STPs • Types of databases • Line information database (LIDB) • Home location register (HLR) • Local number portability (LNR)

  18. SS7 Network http://www.pt.com/tutorials/ss7/

  19. SS7 Protocol Stack Securing SS7 Telecommunications Networks - http://www.itoc.usma.edu/Workshop/2001/Authors/Submitted_Abstracts/paperW2A3.pdf

  20. MTP • Message Transfer Part • Level 1: Physical layer • Level 2: Reliable transfer of signaling information between Signaling Points (SPs) • Level 3: Message routing and Network management

  21. TUP • TUP – Telephone User Part • International telephone control signaling functions • Doesn’t support advanced features • Being phased out in favor of ISUP

  22. ISUP • ISUP – ISDN User Part • Compatible with TUP • Supports both analog and digital voice circuits • Supports both ISDN and non ISDN calls • Defines the protocol used to setup, manage, and release trunk circuits that carry voice and data between SSPs

  23. SCCP & TCAP • SCCP – Signaling Connection Control Part • Provides functionality for MTP (Message Transfer Part) • Supports both connectionless and connection-oriented • Global Title Translation • TCAP – Transaction Capabilities Application Part • Deployment of Advanced Intelligent network services

  24. Role of SS7 • SS7 carries information of every call in the network • SS7 provide the bridge between circuit and packet switched networks • The private nature of SS7 networks is critical for security and reliability

  25. Self Test • SS7 uses ____________ type of Signaling • In-band • Out-band

  26. Self Test • SS7 _________ Multi-frequency Signaling • Uses • Does not Use

  27. Self Test • Identify elements of the figure?

  28. Self Test • SSPs and STPs are not commonly deployed in pairs

  29. Self Test • SCPs are always deployed in pairs

  30. Self Test • 800 numbers are charged to the Calling party

  31. Self Test • A link connects an STP and either SCP or SSP

  32. Self Test • Basic unit of communication links is • 16 Kbps • 32 Kbps • 56 Kbps • 64 Kbps

  33. Questions • ????

More Related