The Medium Access Control Sublayer

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1 The Medium Access Control Sublayer
Chapter 4 The Medium Access Control Sublayer

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

3 Data Link Sub layers LLC MAC

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

5 Teknik 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.

6 Teknik Media Access Control
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

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

8 Teknik Access Control – berbagi media
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 .

9 Teknik Access Control – berbagi media
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.

10 Teknik Access Control – berbagi media
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

11 Teknik Media Access Control – tidak berbagi media
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 .

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

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

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

15 Permasalahan Alokasi Kanal.
Static Channel Allocation in LANs and MANs Dynamic 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 :
Slotted time Time divided as interval-interval discrete time (slot) transmision frame always start at the 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
ALOHA Carrier Sense Multiple Access Protocols Collision-Free Protocols Limited-Contention Protocols Wavelength Division Multiple Access Protocols Wireless LAN Protocols

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

21 User possible to transmit anytime if they have the data
Pure ALOHA Basic Idea : User possible to transmit anytime if they have the data Sender will knows the frame was send damage or not after 270 ms No Sense system Using contention system

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

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

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

25 Persistent and Nonpersistent 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

26 Persistent and Nonpersistent CSMA
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

29 CSMA/CD Reduce the time and bandwidth 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 Collision-Free Protocols
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

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 Example : 0010,0100,1001,1010
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.

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

38 Ethernet Ethernet Cabling Manchester Encoding
The Ethernet MAC Sublayer Protocol The Binary Exponential Backoff Algorithm Ethernet Performance Switched Ethernet Fast Ethernet Gigabit Ethernet IEEE 802.2: Logical Link Control Retrospective on Ethernet

39 The most common kinds of Ethernet cabling.

40 10Base5  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. 10Base2  disebut juga Thin Ethernet dihubungkan dengan BNC yang mem- bentuk T junction  BNC T junction connector.

41 10BaseT menggunakan Twist pair cable dilengkapi dengan HUB
Pd 10BaseT – tidak ada share cable, masing2 stasiun dihubungkan ke HUB dengan dedicated cable. 10BaseF  menggunakan Fiber Optik - mahal, - mempunyai security/ noise imunnity yang bagus - lebih susah pemasangannya dp yang lainnya - 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)

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 Transceiver and connection to coax cable - 100 m max per segment
Coax Cable segment ( 500 m max ) Coax cable Transceiver cable 50 m max Transceiver and connection to coax cable m max per segment stasiun Batasan-batasan single Ethernet cable segment

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

49 Collision Window - minimum packet size
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

50 Sesaat sebelum paket A sampai, B mengirim paket  tabrakan
t + st 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 B 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 2n-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 2n - 1 Disebut Binary Exponential Back Off Algorithm. Bila tabrakan sampai 16x  dianggap jaringan rusak

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

56 A simple example of switched Ethernet.

57 Switched Ethernet 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

58 Switched Ethernet 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 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 Fast Ethernet 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

60 Fast Ethernet 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 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
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 - Frame bursting

64 Gigabit Ethernet A two-station Ethernet. A multistation Ethernet.

65 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 Stack The Physical Layer The MAC Sublayer Protocol The Frame Structure Services

69 The 802.11 Protocol Stack 3 teknik transmisi pada wireless :
Infra-red  seperti remote control pada TV Transmisi pada 0.85 atau 0.95 mikron. Kecep : 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)

70 The Protocol Stack Short range radio FHSS ( Freq Hopping Spread Spectrum) dan DSSS( Direct sequence Spread Sectrum) Menggunakan 79 kanal masing2 1 MHz 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.

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

72 Part of the 802.11 protocol stack.

73 The 802.11 MAC Sublayer Protocol
(a) The hidden station problem. (b) The exposed station problem.

74 The 802.11 MAC Sublayer Protocol (2)
The use of virtual channel sensing using CSMA/CA.

75 The 802.11 MAC Sublayer Protocol (3)
A fragment burst.

76 The 802.11 MAC Sublayer Protocol (4)
Interframe spacing in

77 The Frame Structure The data frame.

78 802.11 Services Association Disassociation Reassociation Distribution
Distribution Services Association Disassociation Reassociation Distribution Integration

79 802.11 Services Authentication Deauthentication Privacy Data Delivery
Intracell Services Authentication Deauthentication Privacy Data Delivery

80 Broadband Wireless Comparison of 802.11 and 802.16
The Protocol Stack The Physical Layer The MAC Sublayer Protocol The Frame Structure

81 The Protocol Stack The Protocol Stack.

82 The 802.16 transmission environment.
The Physical Layer The transmission environment.

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

84 The 802.16 MAC Sublayer Protocol
Service Classes Constant bit rate service Real-time variable bit rate service Non-real-time variable bit rate service Best efforts service

85 The Frame Structure A generic frame. A bandwidth request frame.

86 Bluetooth Bluetooth Architecture Bluetooth Applications The Bluetooth Protocol Stack The Bluetooth Radio Layer The Bluetooth Baseband Layer The Bluetooth L2CAP Layer The 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.y Local Internetworking Spanning Tree Bridges Remote Bridges Repeaters, Hubs, Bridges, Switches, Routers, Gateways Virtual LANs

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

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

94 6.Bridge support security to the organization
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. Each using the different frame format. 802.3 : Xerox 802.4 : General motor, Boing, Motorola does not want to change  not compatible 802.5 : IBM 802.3 allowed Mbps (10 Mbps) 802.4 allowed (10 Mbps) 802.5 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

97 802.5 : unlimited, depend on THT
802.3 : 1518 bytes 802.4 : 8191 bytes 802.5 : unlimited, depend on THT The default of THT 10 msec  5000 bytes P SD AC FC DA/SA L D PAD CS ED FS 802-3 802-4 802-5 IEEE 802 Frame-format

98 Another Problems : 802.3 ke 802.3 : no problem
802.4 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 . 802.5 to also has problem as above

99 Operation of a LAN bridge from 802.11 to 802.3.
Bridges from 802.x to 802.y Operation of a LAN bridge from to

100 The IEEE 802 frame formats. The drawing is not to scale.
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 Every things are transparent
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 Two parallel transparent bridges.
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 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 A building with centralized wiring using hubs and a switch.
Virtual LANs A building with centralized wiring using hubs and a switch.

110 Virtual LANs (2) (a) Four physical LANs organized into two VLANs,
gray and white, by two bridges. (b) The same 15 machines organized into two 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 802.3 (legacy) and 802.1Q Ethernet frame formats.
The IEEE 802.1Q Standard (2) The (legacy) and 802.1Q Ethernet frame formats.

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