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The Medium Access Control Sublayer Chapter 4.  Menyatakan bahwa DDL berkaitan dengan NL dan PL serta menjalankan baik software and hardware. 2 Data Link.

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Presentasi berjudul: "The Medium Access Control Sublayer Chapter 4.  Menyatakan bahwa DDL berkaitan dengan NL dan PL serta menjalankan baik software and hardware. 2 Data Link."— Transcript presentasi:

1 The Medium Access Control Sublayer Chapter 4

2  Menyatakan bahwa DDL berkaitan dengan NL dan PL serta menjalankan baik software and hardware. 2 Data Link Layer – Accessing the Media

3 3 Data Link Sub layers LLC MAC

4  Menjelaskan pentingnya controlling access ke media 4 Media Access Control Techniques Tanpa pengontrol an  Bergantian  Semakin tinggi tingkat pengontrolan- nya semakin besar overhead nya.

5  Media access control : –Mengatur peletakkan frame data ke media. –Ada beberapa metode untuk mengendalikan akses ke media. –Teknik pengendalian akses media didefinisikan bila dan bagaimana nodes men-share media. 5 Teknik Media Access Control

6  Metoda dari media access control dilakukan tergantung pada: –Berbagi Media – bila dan bagaimana node berbagi ke media. –Topologi - Bagaimana hubungan antar node yang nampak pada data link layer 6 Teknik Media Access Control

7  Menyatakan dua metode media access control untuk berbagi media dan dasar karakteristik dari masing2. 7 Teknik Media Access Control - berbagi media

8  Dua metoda yang sering dipakai adalah : –CSMA/Collision Detection  Pada CSMA/Collision Detection (CSMA/CD), node akan memonitor media apakah ada sinyal data,  Bila tidak ada, berarti media free (kosong) sehingga node akan mengirim data. 8 Teknik Access Control – berbagi media

9  Bila suatu sinyal terdeteksi dan menandakan bahwa ada node lain yang sedang mengirim data pada saat yang bersamaan, semua perangkat akan berhenti mengirim dan akan mengulang beberapa saat kemudian. Metode ini yang akhirnya dipakai oleh Ethernet. 9 Teknik Access Control – berbagi media

10  CSMA/Collision Avoidance –Pada CSMA/Collision Avoidance (CSMA/CA), node akan memeriksa apakah media kosong atau tidak. – Bila media kosong (free) maka node akan mengirim notifikasi pada media untuk keperluan akan menggunakannya. –Kemudian node akan mengirimkan datanya. Metode ini dipakai oleh wireless networking technologies 10 Teknik Access Control – berbagi media

11  Media access control protocols untuk non-shared media  Membutuhkan sedikit atau tanpa kontrol sebelum menempatkan frame pada media..  Protocol ini mempunyai aturan dan prosedur yang sederhana untuk media access control.  Topologi point-to-point. 11 Teknik Media Access Control – tidak berbagi media

12  Menggambarkan tujuan dari topologi logical dan identifikasi beberapa topologi logical yang umum. Teknik Media Access Control

13  Indetifikasi karakteristik dari topologi multi- access dan mendiskripsikan implikasi media akses bila menggunakan topologi ini. Teknik Media Access Control

14  Identifikasi karakteristik dari topologi ring dan mendiskripsikan implikasi media akses bila menggunakan topologi ini. Teknik Media Access Control

15 Permasalahan Alokasi Kanal. Static Channel Allocation in LANs and MANsStatic Channel Allocation in LANs and MANs Dynamic Channel Allocation in LANs and MANsDynamic Channel Allocation in LANs and MANs

16 Dynamic Channel Allocation in LANs and MANs  Station Model.  Single Channel Assumption.  Collision Assumption.  (a) Continuous Time. (b) Slotted Time.  (a) Carrier Sense. (b) No Carrier Sense.

17 Diasumsikan dan disepakati bersama bahwa : Diasumsikan dan disepakati bersama bahwa : Slotted time  Time divided as interval-interval discrete time (slot)  transmision frame always start at the beginning of the slot. beginning of the slot. Carrier Sense  Station always sense the line before use it.

18 No Carrier Sense  station not always sense the line before use it.  After a few of time, the station know the transmission fail or not.

19 Multiple Access Protocols ALOHAALOHA Carrier Sense Multiple Access ProtocolsCarrier Sense Multiple Access Protocols Collision-Free ProtocolsCollision-Free Protocols Limited-Contention ProtocolsLimited-Contention Protocols Wavelength Division Multiple Access ProtocolsWavelength Division Multiple Access Protocols Wireless LAN ProtocolsWireless LAN Protocols

20 The first Protocol : ALOHA Protocol –Pure Aloha -Slotted) Aloha  Univesity of Hawaii year : 1970  Norman Abramson  Radio Packet Network

21 Pure ALOHA Basic Idea : oUser possible to transmit anytime if they have the data oSender will knows the frame was send damage or not after 270 ms oNo Sense system oUsing contention system

22 Pure ALOHA In pure ALOHA, frames are transmitted at completely arbitrary times.

23 Pure ALOHA (2) Vulnerable period for the shaded frame.

24 Pure ALOHA (3) Throughput versus offered traffic for ALOHA systems.

25 Presistent CSMA : Presistent CSMA :  If station has data  sense the line  The line busy  station wait for a several time  The line empty  send the frame  If Collision occurred  station wait for a few time then try to re-send  Call 1 presistent because the probability of transmit = 1, if the line is empty. Presistent : ALWAYS detect the line until really empty Presistent : ALWAYS detect the line until really empty Persistent and Nonpersistent CSMA

26 Comparison of the channel utilization versus load for various random access protocols.

27 The possibility collision occure:  Station detect the line ‘ empty ‘ but maybe the packet just sent from another station not yet arrive. This because of the delay propagation.  2 stations at the same time wait the line which has been used by the another station. If the transmission just finish then the both stations together send the packet and access the line.   COLLISION!!

28 Packet Time delay : The Duration time between packet sent by the sender until ALL packets receive by the receiver.  very important The Duration time between packet sent by the sender until ALL packets receive by the receiver.  very important

29 CSMA/CD  CD : Collision Detection  After know there was a collision  cancel the transmission, without waiting the sending frame finish  Reduce the time and bandwidth  MODUL used in CSMA / CD has 3 periods : –transmit –contention –idle

30 CSMA with Collision Detection CSMA/CD can be in one of three states: contention, transmission, or idle.

31  At CSMA/CD probably will collide in the interval “ Contention”  If  ( length of line) large and frame is short – the critical time (contention) more longer  handle by Bit map Protocol Collision-Free Protocols

32 At the Collision Free Protocol :  Access to the channel by the Station, same as a sequence of the bit map  Every stasion has the unique allocation time for access the line and cannot use by another stasion.  If the stasion not ready when their turn comes up, they must wait their turn in the next period.

33 Collision-Free Protocols The basic bit-map protocol. Example : There are, 8 stations, 8 contention slot Interval divided into 2 : contention dan frame

34 Binary Count Down The overhead of the protocol = 1 bit per station. That will develop by using the same length of address and broadcasting to the network. Every position of bit from the different station must OR and called Binary Count Down. How to Compare is as: Example : 0010,0100,1001,1010

35 Collision-Free Protocols (2) The binary countdown protocol. A dash indicates silence.

36 Wireless LAN Protocols A wireless LAN. (a) A transmitting. (b) B transmitting. (a) A transmitting. (b) B transmitting.

37 Wireless LAN Protocols (2) The MACA protocol. (a) A sending an RTS to B. (a) A sending an RTS to B. (b) B responding with a CTS to A.

38 Ethernet Ethernet CablingEthernet Cabling Manchester EncodingManchester Encoding The Ethernet MAC Sublayer ProtocolThe Ethernet MAC Sublayer Protocol The Binary Exponential Backoff AlgorithmThe Binary Exponential Backoff Algorithm Ethernet PerformanceEthernet Performance Switched EthernetSwitched Ethernet Fast EthernetFast Ethernet Gigabit EthernetGigabit Ethernet IEEE 802.2: Logical Link ControlIEEE 802.2: Logical Link Control Retrospective on EthernetRetrospective on Ethernet

39 Ethernet Cabling The most common kinds of Ethernet cabling.

40 o10Base5  disebut juga Thick Ethernet, dihubungkan dengan Vampire tap.  Pd 10Base5 dihubungkan ke transceiver yang mempunyai el-circuit sbg pendeteksi collision  Controller bertanggung jawab thd essembling data kedalam format yang sesuai. o10Base2  disebut juga Thin Ethernet dihubungkan dengan BNC yang mem- bentuk T junction  BNC T junction connector. dihubungkan dengan BNC yang mem- bentuk T junction  BNC T junction connector.

41 o10BaseT  menggunakan Twist pair cable dilengkapi dengan HUB  Pd 10BaseT – tidak ada share cable, masing2 stasiun dihubungkan ke HUB dengan dedicated cable. o10BaseF  menggunakan Fiber Optik - mahal, - mahal, - mempunyai security/ noise imunnity yang - mempunyai security/ noise imunnity yang bagus bagus - lebih susah pemasangannya dp yang - lebih susah pemasangannya dp yang lainnya lainnya - digunakan terutama untuk antar bangunan - digunakan terutama untuk antar bangunan

42 Ethernet Cabling (2) Three kinds of Ethernet cabling. (a) 10Base5, (b) 10Base2, (c) 10Base-T.

43  Untuk mendeteksi kabel putus, bad-tap dll digunakan teknik dengan menggunakan echo  disebut time domain reflectometry.

44 Ethernet Cabling (3) – Cable Topologies a) Linear (Room-room) b) Spine (basement-roof) c) Tree (general topology) d) Segmented (per segment) segment)

45 Ethernet Cabling (4) (a) Binary encoding, (b) Manchester encoding, (c) Differential Manchester encoding. Ethernet tidak menggunakan Diff M.E

46 Ethernet MAC Sublayer Protocol Frame formats. (a) DIX Ethernet, (b) IEEE DIX = DEC, Intel, Xerox

47 Coax Cable segment ( 500 m max ) Transceiver cable 50 m max Coax cable Transceiver and connection to coax cable m max per segment stasiun Batasan-batasan single Ethernet cable segment

48 Konfigurasi Ethernet - Yang “besar” Seg 1 Seg 2 Seg 4 Seg 5 stasiun repeater Seg 3 Kabel koox Remote repeater Point to point link

49 Periode waktu dari mulainya transmisi, selama stasiun pada “vulnareble to collision”. Contoh dalam kondisi terjelek sebagai berikut : Bila waktu propagasi sinyal dari ujung ke ujung jaringan adalah : 22,5  sec yaitu = 225 bit times pada 10 Mbps Collision Window - minimum packet size

50  Sesaat sebelum paket A sampai, B mengirim paket  tabrakan  A mendengar ada tabrakan setelah : (t+22,5)+22,5  sec atau : 45  sec = 450 bit time sesudah A mulai mengirim Collision Window : 450 bit time A B t + st Pada saat ‘ t’ mulai transmisi t paket dari A hampir sampai di B

51  Minimum paket size : 64 oktets 64 oktet = 64 x 8 x 0,1 = 51,2  sec atau = 512 bit times Minimum paket harus > dari collision window Bagaimana kalau < ??  Pada Ethernet : tidak menjamin pesan akan sampai ditujuan pada waktu yang pasti non deterministik

52 Ethernet MAC Sublayer Protocol (2)

53 Back Off Algorithm  Untuk meng-akomodasikan jarak terjauh yang dibolehkan oleh ethernet, slot time harus min 512 bit time atau 51,2 µsec  Setelah tabrakan yang pertama  harus menunggu 0 atau 1 slot time sebelum mengirm lagi. Setelah tabrakan yang kedua  harus menunggu 0,1,2,3 random….dst  Setelah tabrakan n kali harus  menunggu 0 sampai 2 n -1 random.  Algoritma ini disebut : Binary Exponential Backoff

54 Binary Exponential Back Off Algorithm  Setelah tabrakan ke-1  menunggu 0-1 slot time sebelum mengirim lagi.  Setelah tabrakan ke-2  menunggu 0,1,2,atau 3 slot time sebelum mengirim lagi.  Dan seterusnya  tabrakan ke-n, harus menunggu 2 n - 1  Disebut Binary Exponential Back Off Algorithm.  Bila tabrakan sampai 16x  dianggap jaringan rusak

55 Ethernet Performance Efficiency of Ethernet at 10 Mbps with 512-bit slot times.

56 Switched Ethernet A simple example of switched Ethernet.

57  Containing a high speed back plane and room for typlcally 4 – 32 plug-in line card, each containing 1 to 8 connector. Most Often each connector has a 10 Base=T twist pair connection to a single host computer.  Each card forms its own collision domain independent of the other Switched Ethernet

58  Trafik meningkat pada Ethernet diatasi dengan :  Menambah kecepatan mis. menjadi 100 Mbps atau 1 Gbps  Menggunakan Switched Ethernet Switch berisi high speed backplane dan card yang masing2 terdiri dari 1-8 konektor Switch berisi high speed backplane dan card yang masing2 terdiri dari 1-8 konektor Bila st mau mengirim Ethernet frame  ke switch. Card check, apakah tujuannya ada pada card yang sama. Bila ya, tinggal dicopy. Bila tidak dikirim lewat high speed backplane ke card di tujuan. Bagaimana kalau ada 2 mesin attach ke plug in card yang sama dan transmit frame pada saat bersamaan? – Coba dipikirkan.

59  Development of Ethernet by increasing thespeed, using more than 10 Mbps. Using Fiber Cabel  One was called FDDI ( Fiber Distributed Data Interchange or Fiber Channel  Must be compatible with Classic Ethernet Fast Ethernet

60  Merupakan pengembangan dari Ethernet, dengan menaikkan kecepatan-nya.  Muncul : FDDI (Fiber Distributed Data Interface) dan Fibre-Channel yang keduanya menggunakan Fiber Optik, menggunakan back-bone dan station management yang complicated  tidak dipakai lagi.  Kemudian Fast Ethernet yang intinya harus kompatible dengan Ethernet sebelumnya.  Kecepatannya menjadi :100 Mbps,

61 Fast Ethernet The original fast Ethernet cabling.

62 Gigabit Ethernet  Lebih cenderung ke hubungan point to point tidak multidrop seperti Ethernet original 10 Mbps  Classic Ethernet (lihat gambar)  Ada 2 mode operasi yang berbeda : 1.Full duplex  trafik 2 arah pd waktu yang sama, apabila menggunakan sentral switch yg dihubungkan ke pc. Dilakukan pembufferan, shg frame bisa dikirim kapan saja  Tidak perlu mengamati saluran  Switch bebas mix dan match kecepatan

63 2.Half Duplex  Bila pc dihubungkan ke HUB bukan switch. HUB tidak melakukan pem- bufferan frame yang datang.  Masih mungkin terjadi tabrakan  diperlu kan standard CSMA/CD  Kecepatan transmisi 100x lebih dp Classic Ethernet, jarak 100x kurang dp Classic Ethernet (25 m).  Untuk mengatasi ini ditambahkan (jelaskan!) - Carrier Extention - Carrier Extention - Frame bursting - Frame bursting

64 Gigabit Ethernet (a)A two-station Ethernet. (b)A multistation Ethernet.

65 Gigabit Ethernet (2) Gigabit Ethernet cabling.

66 IEEE 802.2: Logical Link Control (a) Position of LLC. (b) Protocol formats.

67 Token bus Token Ring

68 Wireless LANs The Protocol StackThe Protocol Stack The Physical LayerThe Physical Layer The MAC Sublayer ProtocolThe MAC Sublayer Protocol The Frame StructureThe Frame Structure ServicesServices

69  3 teknik transmisi pada wireless :  Infra-red  seperti remote control pada TV Transmisi pada 0.85 atau 0.95 mikron.Transmisi pada 0.85 atau 0.95 mikron. Kecep : 1 Mbps menggunakan 4 ke 16 bit code word(kombinasi dan satu -1)  gray codeKecep : 1 Mbps menggunakan 4 ke 16 bit code word(kombinasi dan satu -1)  gray code 2 Mbps menggunakan 2 ke 4 bit coceword satu -1 (0001,0010 dll)2 Mbps menggunakan 2 ke 4 bit coceword satu -1 (0001,0010 dll) The Protocol Stack

70  Short range radio  FHSS ( Freq Hopping Spread Spectrum) dan DSSS( Direct sequence Spread Sectrum) Menggunakan 79 kanal masing2 1 MHzMenggunakan 79 kanal masing2 1 MHz tanpa ijin (2.4 GHz ISM band) mis: remote pintu garasi, microwave oven, cordless telephone ( 1-2 Mbps)tanpa ijin (2.4 GHz ISM band) mis: remote pintu garasi, microwave oven, cordless telephone ( 1-2 Mbps) DSSS 1 atau 2 Mbps mirip dengan sistem CDMA. Masing2 dikirim dengan 11 chips dengan menggunakan : Barker sequence. Menggunakan PSM.DSSS 1 atau 2 Mbps mirip dengan sistem CDMA. Masing2 dikirim dengan 11 chips dengan menggunakan : Barker sequence. Menggunakan PSM. The Protocol Stack

71  OFDM(Orthogonal-FDM) dan HR(High Rate)-DSSS bekerja pada sampai 54 Mbps dan 11 Mbps The Protocol Stack

72 Part of the protocol stack.

73 The MAC Sublayer Protocol (a) The hidden station problem. (b) The exposed station problem.

74 The MAC Sublayer Protocol (2) The use of virtual channel sensing using CSMA/CA.

75 The MAC Sublayer Protocol (3) A fragment burst.

76 The MAC Sublayer Protocol (4) Interframe spacing in

77 The Frame Structure The data frame.

78 Services AssociationAssociation DisassociationDisassociation ReassociationReassociation DistributionDistribution IntegrationIntegration Distribution Services

79 Services AuthenticationAuthentication DeauthenticationDeauthentication PrivacyPrivacy Data DeliveryData Delivery Intracell Services

80 Broadband Wireless Comparison of and Comparison of and The Protocol StackThe Protocol Stack The Physical LayerThe Physical Layer The MAC Sublayer ProtocolThe MAC Sublayer Protocol The Frame StructureThe Frame Structure

81 The Protocol Stack The Protocol Stack.

82 The Physical Layer The transmission environment.

83 The Physical Layer (2) Frames and time slots for time division duplexing.

84 The MAC Sublayer Protocol Service Classes Constant bit rate serviceConstant bit rate service Real-time variable bit rate serviceReal-time variable bit rate service Non-real-time variable bit rate serviceNon-real-time variable bit rate service Best efforts serviceBest efforts service

85 The Frame Structure (a)A generic frame. (b)A bandwidth request frame.

86 Bluetooth Bluetooth ArchitectureBluetooth Architecture Bluetooth ApplicationsBluetooth Applications The Bluetooth Protocol StackThe Bluetooth Protocol Stack The Bluetooth Radio LayerThe Bluetooth Radio Layer The Bluetooth Baseband LayerThe Bluetooth Baseband Layer The Bluetooth L2CAP LayerThe Bluetooth L2CAP Layer The Bluetooth Frame StructureThe Bluetooth Frame Structure

87 Bluetooth Architecture Two piconets can be connected to form a scatternet.

88 Bluetooth Applications The Bluetooth profiles.

89 The Bluetooth Protocol Stack The version of the Bluetooth protocol architecture.

90 The Bluetooth Frame Structure A typical Bluetooth data frame.

91 Data Link Layer Switching Bridges from 802.x to 802.yBridges from 802.x to 802.y Local InternetworkingLocal Internetworking Spanning Tree BridgesSpanning Tree Bridges Remote BridgesRemote Bridges Repeaters, Hubs, Bridges, Switches, Routers, GatewaysRepeaters, Hubs, Bridges, Switches, Routers, Gateways Virtual LANsVirtual LANs

92  To connect LAN-LAN  On the Data Link Layer  Usually for 802 LAN  Only discuss Bridge  The reason why an organization using several LAN 1. Different needs of many Universities / 1. Different needs of many Universities / Departements  Several LAN need bridge Departements  Several LAN need bridge BRIDGE

93 2. The different geographies – many building in the separate area building in the separate area 3. Overload - thousands workstation - Need to divided into several LAN - Need to divided into several LAN - Need Bridge - Need Bridge 4.The distance between machines too far (mis > 2,5 km) (mis > 2,5 km)  Using the single cable – the round trip delay is large  Need divided into several LAN  Need bridge

94 5. Bridge can select which is continue or not  using programming  not only copy  Repeater 6.Bridge support security to the organization

95 The problem of the BRIDGE between 802.X DAN 802.Y 1.1.Each using the different frame format.  : Xerox  : General motor, Boing, Motorola does not want to change  not compatible  : IBM allowed Mbps (10 Mbps) allowed (10 Mbps) allowed (10 Mbps) allowed Mbps (4 Mbps) allowed Mbps (4 Mbps)

96  The / to buffer needed  The ke need band width expansion because there is collision in 802.3’S 3. The differences between maximum frame length

97  : 1518 bytes  : 8191 bytes  : unlimited, depend on THT  The default of THT 10 msec  5000 bytes P SDACFCDA/SALDPADCSEDFS IEEE 802 Frame-format

98 Another Problems :  ke : no problem  ke : there are 2 problems : has preority, does not has priority  ignored –802.4 has 1 bit in the header as sender, token ack from destination.  to also has problem as above

99 Bridges from 802.x to 802.y Operation of a LAN bridge from to

100 Bridges from 802.x to 802.y (2) The IEEE 802 frame formats. The drawing is not to scale.

101 Local Internetworking A configuration with four LANs and two bridges.

102 TRANSPARENT BRIDGE  Every things are transparent  Just plug between networks without any changes at all  the system will run  Works as, ‘promises mode’, receive every frame, send to many LAN and many direction  Bridge works depend on address table in the bridge to find which frame discard or not.

103  Routing procedure depend on sender and frame’s receiver  a)If receiver and sender comes from the same LAN  frame will be discard b) If receiver and sender comes from the different LAN  frame will be pass c)If receiver and sender not clear and unknown  using flooding  Flooding : sometimes create the trouble  because they must copy every frame Handle by  Spanning Tree Bridge

104 Spanning Tree Bridges Two parallel transparent bridges.

105 Spanning Tree Bridges (2) (a) Interconnected LANs. (b) A spanning tree covering the LANs. The dotted lines are not part of the spanning tree.

106 Remote Bridges Remote bridges can be used to interconnect distant LANs.

107 Repeaters, Hubs, Bridges, Switches, Routers and Gateways (a) Which device is in which layer. (b) Frames, packets, and headers.

108 Repeaters, Hubs, Bridges, Switches, Routers and Gateways (2) (a) A hub. (b) A bridge. (c) a switch.

109 Virtual LANs A building with centralized wiring using hubs and a switch.

110 Virtual LANs (2) (a) Four physical LANs organized into two VLANs, (a) Four physical LANs organized into two VLANs, gray and white, by two bridges. gray and white, by two bridges. (b) The same 15 machines organized into two (b) The same 15 machines organized into two VLANs by switches. VLANs by switches.

111 The IEEE 802.1Q Standard Transition from legacy Ethernet to VLAN-aware Ethernet. The shaded symbols are VLAN aware. The empty ones are not.

112 The IEEE 802.1Q Standard (2) The (legacy) and 802.1Q Ethernet frame formats.

113 Summary Channel allocation methods and systems for a common channel.


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