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Pertemuan 25 High Speed Network

Matakuliah : H0174/Jaringan Komputer Tahun : 2006 Versi : 1/0. Pertemuan 25 High Speed Network. Learning Outcomes. Pada akhir pertemuan ini, diharapkan mahasiswa akan mampu : Menunjukkan Teknik High Speed transmission. Outline Materi. Frame Relay xDSL. Frame Relay.

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Pertemuan 25 High Speed Network

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  1. Matakuliah : H0174/Jaringan Komputer Tahun : 2006 Versi : 1/0 Pertemuan 25High Speed Network

  2. Learning Outcomes Pada akhir pertemuan ini, diharapkan mahasiswa akan mampu : • Menunjukkan Teknik High Speed transmission

  3. Outline Materi • Frame Relay • xDSL

  4. Frame Relay • Frame Relay is a packet-switched, connection-oriented, WAN service. • Frame Relay operates at the data link layer of the OSI reference model. • Frame Relay uses a subset of the high-level data-link control (HDLC) protocol called Link Access Procedure for Frame Relay (LAPF) • Designed to be more efficient than X.25

  5. Frame Relay • Call control carried in separate logical connection • Multiplexing and switching at layer 2 • Eliminates one layer of processing • No hop by hop error or flow control • End to end flow and error control (if used) are done by higher layer • Single user data frame sent from source to destination and ACK (from higher layer) sent back

  6. Frame Relay Mesh

  7. Advantages and Disadvantages • Lost link by link error and flow control • Increased reliability makes this less of a problem • Streamlined communications process • Lower delay • Higher throughput • ITU-T recommend frame relay above 2Mbps

  8. Terminology • The connection through the Frame Relay network between two DTEs is called a virtual circuit (VC). • Generally, permanent virtual circuits (PVCs) that have been preconfigured by the carrier are used. • Virtual circuits may be established dynamically by sending signaling messages to the network. In this case they are called switched virtual circuits (SVCs).

  9. Frame Relay Functions • Frame Relay receives a packet from the network layer protocol, such as IP. • Frame Relay wraps it with a layer 2 address field which contains the DLCI. • The frame is then passed to the physical layer and transmitted on the wire.

  10. Frame Relay Features • Based on packet (frame) switching • Frames of variable length - up to 4096 bytes, typically 1600 bytes • Connection oriented - PVC • High data rates at user-network interfaces - 2Mbps, ultimately up to 45 Mbps • Bandwidth on demand • No flow control mechanisms (nearly) • No retransmission mechanisms • All protocol functions implemented at 2nd level (data link) of OSI model • Physical interface: X.21, V.35, G.703, G.704

  11. Frame Relay network VCIs in Frame Relay are called DLCIs

  12. 192kbps User traffic EIR 256kbps CIR 64kbps time Parameters of a UNI interface • Physical speed - just clock rate • Guaranteed bandwidth parameters • CIR: Committed Information Rate • BC: Committed Burst Size • Extended bandwidth parameters • EIR: Extended Information Rate • BE: Extended Burst Size • TC: Measurement Interval

  13. Frame Relay frame • Flag - Frame marker (1 byte: 01111110) • Address field - two bytes • FCS: Frame Check Sequence (Control Sum)

  14. Link Management Interface (LMI) • For DTE to dynamically acquire information about the status of the network to help verify the integrity of logical and physical links. • LMI messages are exchanged between the DTE and DCE using reserved DLCIs • Three types of LMI: • Cisco • ANSI (T1.617 Annex D • ITU standard Q933 Annex A

  15. Transmission direction FRAD FRAD BECN FECN Flow and congestion control • There is no explicit flow control in FR; the network informs a user about congestion • Congestion: FR frames are discarded from overflowed buffers of switching devices • Congestion information: • FECN - Forward Explicit Congestion Notification • BECN - Backward Explicit Congestion Notification • There are recommendations for access devices what to do with FECN and BECN (usually not implemented)

  16. DSL Access Technology • Why is DSL attractive? • Shannon limit of data rate is 30,000 bps (3-KHz, 30 dB S/N channel) • Digital transmission over loop (DSL) improves data rate • T1/DS1 (1.544Mbps) 18,000 feet • T2/DS2 (6.312 Mbps) 12,000 feet

  17. DSL Limitations • Loop conditions with no direct copper to the house • Loaded coils in loop (used to increase analog distance) cannot carry digital signal • Modern subdivisions have fiber to the neighborhood or curb with digital mux • Operating company inventory dated (administrative issue)

  18. ADSL Loop Broadband ATU-C Splitter Splitter ATU-R Network Voice Voice ADSL Network • ADSL .. Asymmetric Digital Subscriber Line • ATU-C ADSL transmission unit - central office • ATU-C ADSL transmission unit - remote/residence • Splitter separates voice and data

  19. Private Public Premises Network Network Network A D S L A c c e s s N e t w o r k OS OS SM TE Broadband Settop Service TV Network Systems Access PDN TE SM Narrowband ATU-C Node ATU-R PC PC I/O Network ADSL ADSL Packet SM TE ISDN ISDN Network STM Packet ATM STM Packet ATM ATM T r a n s p o r t M o d e s ADSL Asynchronous Digital Subscriber Line ATM Asynchronous Transfer Mode STM Synchronous Transfer Mode TE Terminal Equipment OS Operations System PDN Premises Distribution Network SM Service Module ADSL Network

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