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NETE0510 ISDN

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  1. NETE0510ISDN Dr. Supakorn Kungpisdan supakorn@mut.ac.th NETE0510: Communication Media and Data Communications

  2. Outline • ISDN Overview • Integrated Digital Network • A Conceptual View of ISDN • ISDN Interfaces and Functions • ISDN Tutorial NETE0510: Communication Media and Data Communications

  3. Traditional Telephone Network VS Integrated Digital Network • Traditional Telephone Networks • Separately designed and administrated transmission and switching systems • Demultiplexing and demodulating are necessary at each switching center • A repeated process results in an accommodation of noise as well as cost • Integration of transmission and switching systems • Achievable when both systems are digital • Using PCM modulation and TDM multiplexing • Switching without decoding along the way • Separate multiplex/demultiplex channel banks are not required NETE0510: Communication Media and Data Communications

  4. Analog Communications w/o ISDN NETE0510: Communication Media and Data Communications

  5. The Integrated Digital Network Multiplex and modulate signals Space-division switch Demultiplex and demodulate signals Analog telephone network PCM: pulse-code modulation NETE0510: Communication Media and Data Communications

  6. Digital Communications with ISDN NETE0510: Communication Media and Data Communications

  7. The Integrated Digital Network (cont’d) • The IDN will combine the coverage of the geographically extensive telephone network with the data carrying capacity of digital data networks in a structure called the “integrated services digital network (ISDN)” • “integrated” refers to the simultaneous carrying of digitized voice and a variety of data traffic on the same digital transmission links and by the same digital exchanges NETE0510: Communication Media and Data Communications

  8. Outline • ISDN Overview • Integrated Digital Network • A Conceptual View of ISDN • ISDN Interfaces and Functions • Transmission Structure • User-Network Interface Configurations • ISDN Protocol Architecture • ISDN Connection • Addressing • Interworking NETE0510: Communication Media and Data Communications

  9. Principles of ISDN 1. Support of voice and non-voice applications using a limited set of standardized facilities • Defines the purpose of ISDN and the means of achieving it 2. Support for switched and non-switched applications • Both circuit-switched and packet-switched connections • Support non-switched services in the form of dedicated lines 3. Reliance on 64-kbps connections • Fundamental block of ISDN • 64 kbps were chosen because it was the standard rate for digitized voice NETE0510: Communication Media and Data Communications

  10. Principles of ISDN (cont’d) 4. Intelligence in the network • Sophisticated serviced beyond simple setup a circuit-switched call • Sophisticated network management and maintenance capabilities • Use of SS7 (signaling system number 7) and intelligent switching nodes in the network 5. Layered protocol architecture • User access to ISDN protocol is a layered architecture that can be mapped to OSI model • Standards can be developed independently for various layers and functions 6. Variety of configurations • More than one physical configuration is possible for implementing ISDN NETE0510: Communication Media and Data Communications

  11. The User Interface NETE0510: Communication Media and Data Communications

  12. The User Interface (cont’d) • User has access to ISDN via a local interface to a digital “pipe”. • Pipes of various sizes are available to satisfy different needs • Pipe to the user’s promises has a fixed capacity but the traffic on the pipe may be a variable mix up to the capacity limit • ISDN requires control signals to instruct how to sort out the time-multiplexed data and provide the required services • Control signals are multiplexed onto the same digital pipe NETE0510: Communication Media and Data Communications

  13. The User Interface (cont’d) • Recommendation from I.410: more than one size of pipe is needed • A single terminal (e.g. a residential telephone) • Multiple terminals (e.g. a residential telephone, PC, and alarm system) • A network of devices attached to a LAN or PBX (ISDN gateway) NETE0510: Communication Media and Data Communications

  14. The User Interface (cont’d) NETE0510: Communication Media and Data Communications

  15. Benefits • The principle benefits of ISDN to the customer can be expressed in terms of cost savings and flexibility • Integrated voice and data means that the user does not have to buy multiple services to meet multiple needs • Access charges to a single line only • Purchasing services based on actual needs • Product diversity, low price, and wide availability of equipment NETE0510: Communication Media and Data Communications

  16. ISDN Architecture NETE0510: Communication Media and Data Communications

  17. ISDN Architecture (cont’d) • Physical interface provides a standardized means of attaching to the network • The interface supports a basic service consisting of three time-multiplexed channels, two at 64 kbps and one at 16 kbps • In addition, there is a primary service that provide multiple 64-kbps channels • An interface is defined between the customer’s terminal equipment (TE) and a device on the customer’s premises, known as a network termination (NT) • The subscriber loop is the physical path from the subscriber’s NT to the ISDN central office • Must support full-duplex digital transmission for both basic and primary data rates NETE0510: Communication Media and Data Communications

  18. ISDN Architecture (cont’d) • ISDN central office connects subscriber loops to the digital network, providing access to lower-layer transmission facilities: • Circuit-switched capabilities • Same facility provided by other digital-switched telecom net’s (64 kbps) • Non-switched capabilities • A 64 kbps dedicated link, higher rates in B-ISDN using PVC in ATM tx • Switched capabilities • High speed (>64 kbps) switched connections using ATM in B-ISDN • Packet-switched capabilities • Resembles packet-switched service provided by other data networks • Frame-mode capabilities • A service that supports frame relay • Common-channel signaling capabilities • Used to control the network and provide call management NETE0510: Communication Media and Data Communications

  19. Outline • ISDN Overview • ISDN Interfaces and Functions • ISDN Standard • Transmission Structure • ISDN Model • Reference Points and Functional Groupings • Access Configurations • ISDN Switch Types • ISDN Tutorial • Network Diagram • Type of Equipment • Configuring your ISDN Line and Equipment • Wiring your Location for ISDN NETE0510: Communication Media and Data Communications

  20. ISDN Standard NETE0510: Communication Media and Data Communications

  21. Transmission Structure • Digital pipe between central office and ISDN subscriber carry a number of communication channels, varies from user to user • The transmission structure of access links includes channels of: • B channel: 64 kbps • D channel: 16 or 64 kbps • H channel: 384 (H0), 1536 (H11), or 1920 (H12) kbps NETE0510: Communication Media and Data Communications

  22. B Channel • A user channel, carrying digital data, PCM-encoded digital voice, or a mixture of lower-rate traffic at a fraction of 64 kbps • The information is carried in frame format, using either high-level data link control (HDLC) or PPP as the Layer 2 protocol. PPP is more robust than HDLC because it provides a mechanism for authentication and negotiation of compatible link and protocol configuration. NETE0510: Communication Media and Data Communications

  23. D Channel • Carry common-channel signaling (CCS) information to control circuit-switched calls • Traffic over the D channel employs the Link Access Procedure on the D Channel (LAPD) protocol. LAPD is a data link layer protocol based on HDLC. • May be used for packet switching or low speed (e.g. 100 bps) telemetry (data transfer over media) when no signaling informationis waiting NETE0510: Communication Media and Data Communications

  24. ISDN Channel Functions NETE0510: Communication Media and Data Communications

  25. H Channel • Provides user information transmission at higher data rates • Use the channel as a high-speed trunk or subdivide it based on TDM • Examples: fast fax, video, high-speed data, high quality audio NETE0510: Communication Media and Data Communications

  26. Basic and Primary Channel Structures NETE0510: Communication Media and Data Communications

  27. Basic Channel Structure • Consist of 2 full-duplex 64-kbps B channels and a full-duplex 16-kbps D channel • With overheads such as framing and synchronization. The total bit rate is 192 kbps • To meet the needs of residential subscribers and small offices • Allow simultaneous use of voice and data applications (packet switching access) e.g. provide a link to a central alarm service, facsimile, teletex, etc. NETE0510: Communication Media and Data Communications

  28. Primary Channel Access • Different data rates in different countries • For users with greater capacity needs • e.g. offices with LAN, PBX • Supporting H channels • When no D channel is present, it is assumed that a D channel on another primary interface at the same subscriber location will provide any required signaling. • Primary rate H0 channel structures (3H0+D, 4H0, and 5H0+D) • Primary rate interface H1 channel structures (one H11 and one H12+D) • Primary rate interface structures for mixed B and H0 channels zero or one D channel plus combination of B and H0 channels (e.g. 3H0+5B+D or 3H0+6B for 1.544-Mbps interface) NETE0510: Communication Media and Data Communications

  29. ISDN Model NETE0510: Communication Media and Data Communications

  30. ISDN Protocols at the user-network interface NETE0510: Communication Media and Data Communications

  31. ISDN Physical Layer • Each ISDN BRI frame contains two sub-frames each containing the following: • 8 bits from the B1 channel, 8 bits from the B2 channel, 2 bits from the D channel, and 6 bits of overhead • So, each BRI frame contains 48 bits NETE0510: Communication Media and Data Communications

  32. ISDN Physical Layer (cont’d) • The overhead bits of an ISDN sub-frame are used as follows: • Framing bit — Provides synchronization • Load balancing bit- Adjusts the average bit value • Echo of previous D channel bits — Used for contention resolution when several terminals on a passive bus contend for a channel • Activation bit — Activates devices • Spare bit — Unassigned NETE0510: Communication Media and Data Communications

  33. ISDN Physical Layer (cont’d) • 4,000 frames are transmitted per second. • Each B channel, B1and B2, has a capacity of 8 * 4000 * 2 = 64 kbps, while channel D has a capacity of 2 * 4000 * 2 = 16 kbps. • This accounts for 144 kbps (B1 + B2 + D) of the total ISDN BRI physical interface bit rate of 192 kbps. • The remainder of the data rate are the overhead bits that are required for transmission: 6 * 4000 * 2 = 48 kbps. NETE0510: Communication Media and Data Communications

  34. ISDN Data-link Layer NETE0510: Communication Media and Data Communications

  35. ISDN Data-link Layer (cont’d) • Layer 2 of the ISDN signaling channel is LAPD. LAPD is similar to HDLC. LAPD is used across the D channel to ensure that control and signaling information is received and flows properly. • The LAPD flag and control fields are identical to those of HDLC. • The LAPD address field is 2 bytes long. • The first address field byte contains the service access point identifier(SAPI), which identifies the portal at which LAPD services are provided to Layer 3. The command/response bit (C/R), indicates whether the frame contains a command or a response. • The second byte contains the terminal endpoint identifier(TEI). NETE0510: Communication Media and Data Communications

  36. ISDN Layer 3: Q.931 Messaging Call Setup NETE0510: Communication Media and Data Communications

  37. (Q.931 Messaging Call Setup) NETE0510: Communication Media and Data Communications

  38. Reference Points and Functional Groupings • ITU-T approach for actual user’s physical configuration • Functional grouping: certain arrangements of physical equipment or combination of equipment • NT1, NT2, TE1, TE2, TA • Reference points: conceptual points of separation of group function • R, S, T, U NETE0510: Communication Media and Data Communications

  39. Functional Groupings • NT1 (Network Termination 1) • Includes functions similar to OSI layer 1 • May be controlled by ISDN provider (a boundary to network) • Isolate the user from the transmission technology of subscriber loop • Supports multiple channels (e.g. 2B+D) using TDM • Might support multiple devices in a multidrop arrangement • E.g. a residential interface might include a telephone, PC, and alarm system, all attached to a single NT1 interface via a multidrop line NETE0510: Communication Media and Data Communications

  40. Functional Groupings (cont’d) • NT2 (Network Termination 2) • An intelligent device that may include up to OSI layer 3 • Perform switching and concentration functions • Switching: the construction of a private network using semi-permanent circuit among a number of sites • Concentration: multiple devices, attached to a digital PBX, LAN, or terminal controller, may transmit data across ISDN • E.g. digital PBX, a terminal controller, LAN • Digital PBX provides NT2 functions at layers 1, 2, and 3 • A simple terminal controller provides layers 1 and 2 • A simple Time Division MUX provides layer 1 NETE0510: Communication Media and Data Communications

  41. Functional Groupings (cont’d) • TE1 (Terminal Equipment type 1) • Devices that support the standard ISDN interface • E.g. digital telephone, integrated voice/data terminal, digital fax • TE2 (Terminal Equipment type 2) • The existing non-ISDN equipment • E.g. physical interface RS-232, host computer with X.25 • Requires a terminal adaptor (TA) to plug into an ISDN interface NETE0510: Communication Media and Data Communications

  42. Functional Groupings (cont’d) • TA (Terminal Adaptor) • Converts standard electrical signals into the form used by ISDN • Needed for connection with TE2 devices • The ISDN TA can be either a standalone device or a board inside the TE2 NETE0510: Communication Media and Data Communications

  43. Reference Points and Functional Groupings NETE0510: Communication Media and Data Communications

  44. Reference Points • Reference point R (connect TE2-TA) • Provides a non-ISDN interface between user equipment that is non-ISDN compatible and adaptor equipment • Comply with X or V series ITU-T recommendation • Reference point S (connect TE1-NT2, TA-NT2) • The interface of individual ISDN terminals • Separate user terminal from network communications functions • Reference point T (connect NT2-NT1) • A minimal ISDN network termination at CPE • Separate network’s provider equipment from the user’s one • Reference point U (connect NT1-provider) • Describes full-duplex data signal on the subscriber line NETE0510: Communication Media and Data Communications

  45. Access Configurations • Based on definitions of functional grouping and reference points, several possible configurations for ISDN user-network interface have been proposed by ITU-T • The most straightforward configuration is that one or more pieces of equipment correspond to each functional grouping: NETE0510: Communication Media and Data Communications

  46. Access Configurations (cont’d) • In second case, the line termination function is combined with other ISDN interface functions • ISDN provider may provide the NT1 function e.g. NT1 may be integrated into a PBX NETE0510: Communication Media and Data Communications

  47. Access Configurations (cont’d) • In the third case, NT2 and TE functions are combined • A host that supports users, but also acts as a packet switch in a private packet-switching network that uses ISDN for trunking NETE0510: Communication Media and Data Communications

  48. Access Configurations (cont’d) • Final case: an ISDN subscriber device can connect directly to the subscriber loop terminator or into a PBX or LAN using the same interfacespecifications and thus ensuring portability NETE0510: Communication Media and Data Communications

  49. Examples of implementation of NT1 and NT2 functions NETE0510: Communication Media and Data Communications

  50. Examples of implementation of NT1 and NT2 functions NETE0510: Communication Media and Data Communications