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Mrežni zahtjevi multimedijalnih aplikacija

Mrežni zahtjevi multimedijalnih aplikacija. Podatkovni višemedijski prijenos i računalne mreže. Miro Capan. Sadržaj za danas:. ATM Multicast. ATM (i).

jorden-zimmerman
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Mrežni zahtjevi multimedijalnih aplikacija

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  1. Mrežni zahtjevi multimedijalnih aplikacija Podatkovni višemedijski prijenos i računalne mreže Miro Capan

  2. Sadržaj za danas: • ATM • Multicast

  3. ATM (i) • ATM je definiran od strane ITU-T (International Union Telecommunication Union - Telecommninication Standardization Sector) i ANSI (American National Standards Institute) • Osnovna ideja - korištenje VLSI tehnologije za prijenos podataka javnim mrežama

  4. ATM (ii) • ATM = Asynchronous Transfer Mode • dizajniran za što jeftiniji prijenos multimedijalnih podataka javnim ili privatnim mrežama velikim brzinama • formalno ATM je prijenosna tehnologija za B-ISDN mreže definirana preporukom ITU-T I.361

  5. ATM (iii) • ATM Forum • organizacija proizvođača i korisnika ATM opreme osnovana s ciljem što lakše implementacije ATM tehnologije u privatnim mrežama i osiguranja interoprabilnosti javnih i privatnih ATM mreža

  6. ITU-T vs ATM Forum

  7. Statističko multipleksiranje (i)

  8. Statističko multipleksiranje (ii) • Prednosti: • dinamičko pridjeljivanje prijenosnog pojasa • korištenje prijenosnog pojasa samo kada postoje podaci za prenijeti

  9. Statističko multipleksiranje (iii)

  10. Uspostavljanje veze

  11. Signalizacija preko UNI • called party number • class of service requested(CBR, VBR-RT, and others) • connection configuration (point-to point or point-to-multipoint) • forward and backward peak cell rates (in cells per second) • forward and backward sustainable cell rates (in cells per second in the case of VBR-RT connections) • forward and backward maximum burst size in the case of VBR-RT connections.

  12. Funkcioniranje

  13. AFI - 1 byte of authority and format identifier. The AFI field identifies the type of address. The defined values are 45 and 39 for E.164 and DCC addresses, respectively. DCC - 2 bytes of data country code DFI - 1 byte of domain specific part (DSP) format identifier AA - 3 bytes of administrative authority RD - 2 bytes of routing domain Area - 2 bytes of area identifier ESI - 6 bytes of end system identifier, which is an IEEE 802 Media Access Control (MAC) address Sel - 1 byte of Network Service Access Point (NSAP) selector E.164 - 8 bytes of Integrated Services Digital Network (ISDN) telephone number ATM adresirnje

  14. ATM slojevi • ATM Adaptacijski sloj • ATM sloj • ATM fizički sloj

  15. ATM Fizički sloj (i) • Physical Medium Sublayer • controls transmission and receipt of bits on the physical medium. • Transmission Convergence Sublayer • Cell delineation - maintains ATM cell boundaries. • Header error control sequence generation and verification Generates and checks the header error control code to ensure valid data.

  16. ATM Fizički sloj (ii) • Transmission Convergence Sublayer • Cell rate decoupling - inserts or suppresses idle (unassigned) ATM cells to adapt the rate of valid ATM cells to the payload capacity of the transmission system. • Transmission frame adaptation - packages ATM cells into frames acceptable to the particular physical-layer implementation. • Transmission frame generation and recovery -generates and maintains the appropriate physical-layer frame structure.

  17. ATM Sloj • Multiplexing and demultiplexing the cells of different virtual connections. These connections are identified by their VCI and VPI values. • Translating the values of the VCI and VPI at the ATM switches or cross connects. • Extracting and inserting the header before or after the cell is delivered to or from the higher ATM adaptation layer. • Handling the implementation of a flow control mechanism at the UNI.

  18. ATM Adaptacijski slojevi (i) • Prevodi tokove podataka viših slojeva u informacijsko polje ATM ćelije (48 bytova)

  19. ATM Adaptacijski slojevi (ii) AAL AAL1 AAL2 AAL3/4 AAL5 Requires timing between source Yes No No No and destination Data rate Constant Variable Variable Variable Connection Connection Connection Connection Connection mode -oriented -oriented less -oriented Traffic types Voice and Data Data Data circuit emulation

  20. Primjer funkcioniranja AAL5

  21. ATM LANE (i) • LANE - LAN Emulation • ATM Forum standard, trenutno postoje verzije 1.0 i 2.0 • osnovna ideja - omogućiti postepeno uvođenje ATM opreme u mrežu kroz davanje podrške postojećim LAN tehnologijama

  22. ATM LANE (ii) • Princip rada - LANE koristi enkapsulaciju na 2. OSI sloj (MAC encapsulation) i tako podržava sve najveći broj protokola 3. OSI Sloja • uređaji spojeni LANE ELAN izgledaju jedan drugome kao da su spojeni na jedan preklapani segment

  23. ATM LANE (iii)

  24. LANE komponente (i) • LAN emulation client (LEC)—End systems that support LANE, such as network interface card (NIC) connected workstations, LAN switches with ATM uplinks or routers that support ATM • LEC emulates an interface to a legacy LAN and performs data forwarding, address resolution, and registration of MAC addresses with the LANE server and communicates with other LECs via ATM virtual channel connections (VCCs).

  25. LANE komponente (ii) • LAN emulation configuration server (LECS) - the LECS maintains a database of ELANs and the ATM addresses of the LESs that control the ELANs. It accepts queries from LECs and responds with the ATM address of the LES that serves the appropriate ELAN/VLAN. This database is defined and maintained by the network administrator.

  26. LANE komponente (iii) • LAN emulation server (LES) • LES provides a central control point for all LECs. • LECs maintain a Control Direct VCC to the LES to forward registration and control information. The LES maintains a point-to-multipoint VCC, known as the Control Distribute VCC, to all LECs. • The Control Distribute VCC is used only to forward control information. As new LECs join the ATM ELAN, each LEC is added as a leaf to the control distribute tree.

  27. LANE komponente (iv) • Broadcast and unknown Server (BUS) • a central point for distributing broadcasts and multicasts. ATM is a point-to-point technology without “any-to-any” or “broadcast” support. • LANE solves this problem by centralizing the broadcast support in the BUS. Each LEC must set up a VCC to the BUS. The BUS then adds the LEC as a leaf to its point-to-multipoint VCC (known as the Multicast Forward VCC). • The BUS also acts as a multicast server.

  28. Funkicioniranje LANE ELANa (i)

  29. Funkicioniranje LANE ELANa (ii)

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