2CFA_SDE AGM LICE

• BHARAT SANCHAR NIGAM LIMITED is a Govt. of India Enterprise
• This is SDE/AGM LICE MATERIAL
• This is AGM/DGM LICE material
• Index


  • 1 SIGNALING IN PSTN
  • 2 NGN ARCHITECTURE
  • 3 NGN PROTOCOLS (SIP/H.248/RTP/SIGTRAN)
  • 4 CDOT MAX NG
  • 5 C5 NGN LMG ARCHITECTURE
  • 6 SSTP IMPLEMENTATION IN BSNL
  • 7 IMS NETWORK ARCHITECTURE
• Signaling


  The process of exchanging information between switching equipment to set up calls
• Types of signaling


  • Subscriber Line signaling
  • Inter-Exchange Signalling
• Subscriber Line signaling


  Signaling between the subscriber and the exchange
• Calling Subscriber Line Signaling

  1. Call request

  2. Address signal

  3. End of selection signal

  4. Answer Back Signal

  5. Release signal

  6. Permanent Line (PG) Signal
• Called Subscriber Line Signaling

  1. Ringing Signal

  2. Answer Signal

  3. Release Signal

  4. Register Recall Signal
• Channel-Associated signalling (CAS)


  Signaling information is conveyed on a separate channel rigidly associated with the speech channel
• Common Channel Signaling System No. 7 (CCS#7)

  A signaling protocol that has become a worldwide standard for modern telecommunications networks
• Key features of CCS#7

  • Internationally standardized
  • Suitable for national, international and intercontinental network level
  • Suitable for various communication services
  • High performance and flexibility
  • High reliability for message transfer
  • Processor-friendly structure of messages
  • Signaling on separate signaling links
  • Signaling links always available, even during existing calls
  • Use of signaling links for transferring user data
  • Used on various transmission media
  • Use of 64 Kbit/s transfer rate typical in digital networks
  • Automatic supervision and control of the signaling network
• Signaling Points (SP)


  The sources and sinks of signaling traffic, primarily the exchanges
• Signaling Transfer Points (STP)


  Switch signaling messages received to another STP or to a SP on the basis of the destination address
• Signaling links


  Consist of a signaling data link and its transfer control functions
• Signaling Modes


  Associated mode: Signaling link is routed together with the circuit group

  Quasi-associated mode: Signaling link and speech circuit group run along different routes
• Signaling Routes


  The route defined for the signaling between an originating point and a destination point
• Network Structure


  Worldwide signaling network is divided into an international level and national level, each with its own numbering plans
• Signaling Functions in CCS7

  • Message Transfer Part (MTP)
  • Function-specific User Parts (UP)
• The MTP represents a user-neutral means of transport for messages between the users
• Each user part encompasses the functions, protocols and coding for the signaling via CCS7 for a specific user type
• Uniform mode of signalling


  Associated or quasi-associated
• Mixed mode of signalling


  Associated and quasi-associated
• Worldwide signalling network


  • Divided into two levels that are functionally independent of each other
  • An international level with an international network
  • A national level with many national networks
  • Each network has its own numbering plans for the SPs
• Signalling functions in CCS7

  • Message transfer part (MTP)
  • Function-specific user parts (UP)
• Message transfer part (MTP)


  User-neutral means of transport for messages between the users
• User part


  Encompasses the functions, protocols and coding for the signalling via CCS7 for a specific user type (e.g. telephone service, data service, ISDN)
• Functions of the MTP and the UP of CCS7

  • Divided into 4 levels
  • Levels 1 to 3 are allotted to the MTP
  • User parts form level 4
• Message exchange between two Signalling Points with CCS7

  1. Messages to be transferred from one UP to another are given to the MTP

  2. MTP ensures messages reach the addressed UP in the correct order without information loss, duplication or sequence alteration and without any bit errors
• Level 1 (Signalling Data Link)


  • Defines the physical, electrical and functional characteristics of a signalling data link and the access units
  • Represents the bearer for a signalling link
  • In a digital network, 64-kbit/s channels are generally used as signalling data links
  • Analog channels (preferably with a bit rate of 4.8 kbit/s) can also be used via modems as a signalling data link
• Level 2 (Signalling Link)

  1. Defines the functions and procedures for a correct exchange of user messages via a signalling link

  2. Delimitation of the signal units by flags

  3. Elimination of superfluous flags

  4. Error detection using check bits

  5. Error correction by re-transmitting signal units

  6. Error rate monitoring on the signalling data link

  7. Restoration of fault-free operation, for example, after disruption of the signalling data link
• Level 3 (Signalling Network)

  1. Defines the inter-working of the individual signalling links

  2. Message handling, i.e. directing the messages to the desired signalling line, or to the correct UP

  3. Signalling network management, i.e. control of the message traffic, for example, by means of changeover of signalling links if a fault is detected and changeback to normal operation after the fault is corrected
• Signal Units (SU)


  • The MTP transport messages in the form of SUs of varying length
  • In addition to the message it also contains control information for the message exchange
• Types of Signal Units

  • Message Signal Units (MSU)
  • Link Status Signal Units (LSSU)
  • Fill-in Signal Units (FISU)
• Message Signal Units (MSU)

  Used to transfer user messages, that is, messages from UPs (level 4) and messages from the signalling network management (level 3)
• Link Status Signal Units (LSSU)


  Contain information for the operation of the signalling link (e.g. of the alignment)
• Fill-in Signal Units (FISU)


  Used to maintain the acknowledgement cycle when no user messages are to be sent in one of the two directions of the signalling link
• Flag


  1. bit pattern 01111110 used to clearly separate SUs from one another
• Backward Sequence Number (BSN)

  1. bit number used as an acknowledgement carrier within the context of error control
• Backward Indicator Bit (BIB)


  1. bit field needed during general error correction