The Medium Access Control Sublayer

The Medium Access ControlThe Medium Access ControlSublayerSublayer

Chapter 4Chapter 4

Menyatakan bahwa DDL berkaitan dengan NL dan PL Menyatakan bahwa DDL berkaitan dengan NL dan PL serta menjalankan baik software and hardware.serta menjalankan baik software and hardware.

22

Data Link Layer – Accessing the MediaData Link Layer – Accessing the Media

33

Data Link Sub layersData Link Sub layers

LLC

MAC

Menjelaskan pentingnya controlling access ke mediaMenjelaskan pentingnya controlling access ke media

44

Media Access Control TechniquesMedia Access Control Techniques

Tanpa pengontrolan

Bergantian Semakin

tinggi tingkat pengontrolan-nya semakin besar overhead nya.

Media access control :Media access control :– Mengatur peletakkan frame data ke media. Mengatur peletakkan frame data ke media. – Ada beberapa metode untuk mengendalikan Ada beberapa metode untuk mengendalikan

akses ke media.akses ke media.– Teknik pengendalian akses media didefinisikan Teknik pengendalian akses media didefinisikan

bila dan bagaimana nodes men-share media.bila dan bagaimana nodes men-share media.

55

Teknik Media Access ControlTeknik Media Access Control

Metoda dari media access control Metoda dari media access control dilakukan tergantung pada:dilakukan tergantung pada:– Berbagi Media – bila dan bagaimana Berbagi Media – bila dan bagaimana

node berbagi ke media. node berbagi ke media.

– Topologi - Bagaimana hubungan antar Topologi - Bagaimana hubungan antar node yang nampak pada data link layernode yang nampak pada data link layer

66


Menyatakan dua metode media access control Menyatakan dua metode media access control untuk berbagi media dan dasar karakteristik dari untuk berbagi media dan dasar karakteristik dari masing2. masing2.

77

Teknik Media Access Control - berbagi mediaTeknik Media Access Control - berbagi media

Dua metoda yang sering dipakai adalah :Dua metoda yang sering dipakai adalah :– CSMA/Collision Detection CSMA/Collision Detection

Pada CSMA/Collision Detection (CSMA/CD), Pada CSMA/Collision Detection (CSMA/CD), node akan memonitor media apakah ada node akan memonitor media apakah ada sinyal data, sinyal data,

Bila tidak ada, berarti media free (kosong) Bila tidak ada, berarti media free (kosong) sehingga node akan mengirim data .sehingga node akan mengirim data .

88

Teknik Access Control – berbagi mediaTeknik Access Control – berbagi media

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

99


CSMA/Collision Avoidance CSMA/Collision Avoidance – Pada CSMA/Collision Avoidance (CSMA/CA), Pada CSMA/Collision Avoidance (CSMA/CA),

node akan memeriksa apakah media kosong node akan memeriksa apakah media kosong atau tidak. atau tidak.

– Bila media kosong (free) maka node akan Bila media kosong (free) maka node akan mengirim notifikasi pada media untuk keperluan mengirim notifikasi pada media untuk keperluan akan menggunakannya.akan menggunakannya.

– Kemudian node akan mengirimkan datanya. Kemudian node akan mengirimkan datanya. Metode ini dipakai oleh 802.11 wireless Metode ini dipakai oleh 802.11 wireless networking technologiesnetworking technologies

1010


Media access control protocols untuk Media access control protocols untuk non-shared media non-shared media

Membutuhkan sedikit atau tanpa Membutuhkan sedikit atau tanpa kontrol sebelum menempatkan frame kontrol sebelum menempatkan frame pada media.. pada media..

Protocol ini mempunyai aturan dan Protocol ini mempunyai aturan dan prosedur yang sederhana untuk media prosedur yang sederhana untuk media access control. access control.

Topologi point-to-point .Topologi point-to-point .1111

Teknik Media Access Control – tidak Teknik Media Access Control – tidak berbagi mediaberbagi media

Menggambarkan tujuan dari topologi logical dan Menggambarkan tujuan dari topologi logical dan identifikasi beberapa topologi logical yang umum. identifikasi beberapa topologi logical yang umum.


Indetifikasi karakteristik dari topologi multi-Indetifikasi karakteristik dari topologi multi-access dan mendiskripsikan implikasi media access dan mendiskripsikan implikasi media akses bila menggunakan topologi ini. akses bila menggunakan topologi ini.


Identifikasi karakteristik dari topologi ring dan Identifikasi karakteristik dari topologi ring dan mendiskripsikan implikasi media akses bila mendiskripsikan implikasi media akses bila menggunakan topologi ini. menggunakan topologi ini.

Teknik Media Access Control Teknik Media Access Control

Permasalahan Alokasi Kanal. Permasalahan Alokasi Kanal.

• Static Channel Allocation in Static Channel Allocation in LANs and MANsLANs and MANs

• Dynamic Channel Allocation in Dynamic Channel Allocation in LANs and MANsLANs and MANs

Dynamic Channel Allocation in LANs and MANsDynamic Channel Allocation in LANs and MANs

Station Model.Station Model. Single Channel Assumption.Single Channel Assumption. Collision Assumption.Collision Assumption. (a)(a) Continuous Time. Continuous Time.

(b)(b) Slotted Time. Slotted Time. (a)(a) Carrier Sense. Carrier Sense.

(b)(b) No Carrier Sense. No Carrier Sense.

Diasumsikan dan disepakati bersama Diasumsikan dan disepakati bersama bahwa :bahwa :

Slotted timeSlotted time Time divided asTime divided as interval-interval dis interval-interval disccrreettee

time time (slot)(slot) transmisitransmisionon frame frame always start at the always start at the

beginning of the slot.beginning of the slot.

Carrier SenseCarrier Sense Station always sense the line before Station always sense the line before use use

it.it.

No Carrier SenseNo Carrier Sense station not always sense the line before station not always sense the line before

use it.use it. After a few of time, the station know the After a few of time, the station know the

transmission fail or not.transmission fail or not.

Multiple Access ProtocolsMultiple Access Protocols

• ALOHAALOHA

• Carrier Sense Multiple Access Carrier Sense Multiple Access ProtocolsProtocols

• Collision-Free ProtocolsCollision-Free Protocols

• Limited-Contention ProtocolsLimited-Contention Protocols

• Wavelength Division Multiple Wavelength Division Multiple Access ProtocolsAccess Protocols

• Wireless LAN ProtocolsWireless LAN Protocols

The first Protocol :The first Protocol :

ALOHAALOHA ProtocolProtocol– Pure AlohaPure Aloha

- SSlotted)lotted) Aloha Aloha

Univesity of Hawaii Univesity of Hawaii year :year : 1970 1970 Norman AbramsonNorman Abramson RRadioadio Packet Network Packet Network

Pure Pure ALOHAALOHA

Basic Idea :Basic Idea :

o User possible to transmit anytime if User possible to transmit anytime if they have the datathey have the data

o Sender will knows the frame was Sender will knows the frame was send damage or not after 270 mssend damage or not after 270 ms

o No Sense systemNo Sense system

o UsingUsing contention contention system system

Pure ALOHAPure ALOHAIn pure ALOHA, frames are transmitted at In pure ALOHA, frames are transmitted at

completely arbitrary times.completely arbitrary times.

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

Pure ALOHA (3)Pure ALOHA (3)Throughput versus offered traffic for ALOHA Throughput versus offered traffic for ALOHA

systems.systems.

Presistent CSMA :Presistent CSMA : If station has data If station has data sense the line sense the line The line busy The line busy station wait for a several time station wait for a several time The line empty The line empty send the frame send the frame

If Collision occurred If Collision occurred station wait for a few time station wait for a few time then try to re-send then try to re-send

CallCall 1 presistent1 presistent because the because the probability of probability of transmit = 1, transmit = 1, if the line is empty.if the line is empty.

PresistentPresistent : : ALWAYS detect the line until really ALWAYS detect the line until really emptyempty

Persistent and Nonpersistent CSMAPersistent and Nonpersistent CSMA

Persistent and Nonpersistent CSMAPersistent and Nonpersistent CSMAComparison of the channel utilization versus Comparison of the channel utilization versus

load for various random access protocols.load for various random access protocols.

The possibility collision occure:The possibility collision occure:

Station detect the line Station detect the line ‘ ‘ emptyempty ‘ ‘ but maybe the but maybe the packet just sent from another station not yet arrive. packet just sent from another station not yet arrive. This because of the delay propagation.This because of the delay propagation.

2 stations at the same time wait the line which has 2 stations at the same time wait the line which has been used by the another station. If the been used by the another station. If the transmission just finish then the both stations transmission just finish then the both stations together send the packet and access the line. together send the packet and access the line. CCOLLISION!!OLLISION!!

Packet Time delayPacket Time delay : :

The Duration time between packet sent by The Duration time between packet sent by the sender until ALL packets receive by the the sender until ALL packets receive by the receiver.receiver. very importantvery important

CSMA/CDCSMA/CD

CD : Collision DetectionCD : Collision Detection After know there was a collision After know there was a collision cancel the cancel the

transmission, without waiting the sending transmission, without waiting the sending frame finishframe finish

Reduce the time andReduce the time and bandwidth bandwidth MODUL MODUL used in used in CSMA / CD CSMA / CD hashas 3 period 3 periodss : :

– transmittransmit

– contentioncontention

– idleidle

CSMA with Collision DetectionCSMA with Collision Detection

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

At CSMA/CD probably will collide in the At CSMA/CD probably will collide in the interval “ Contention”interval “ Contention”

If If ( length of line) large and frame is ( length of line) large and frame is short – the critical time (contention) more short – the critical time (contention) more longer longer handle by handle by Bit mapBit map Protocol Protocol

Collision-Free ProtocolsCollision-Free Protocols

At the At the Collision Free ProtocolCollision Free Protocol : :

Access to the channel by the Station, same as Access to the channel by the Station, same as a sequence of the bit mapa sequence of the bit map

Every stasion has the unique allocation time Every stasion has the unique allocation time for access the line and cannot use by for access the line and cannot use by another stasion. another stasion.

If the stasion not ready when their turn If the stasion not ready when their turn comes up, they must wait their turn in the comes up, they must wait their turn in the next period.next period.

Collision-Free ProtocolsCollision-Free Protocols

The basic bit-map protocol.The basic bit-map protocol.

Example : There are, 8 stations, 8 contention slot Interval divided into 2 :

contention dan frame

Binary Count DownBinary Count Down

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

ExampleExample : 0010,0100,1001,1010 : 0010,0100,1001,1010

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

indicates silence.indicates silence.

Wireless LAN ProtocolsWireless LAN Protocols

A wireless LAN. A wireless LAN.

(a)(a) A transmitting. A transmitting. (b)(b) B transmitting. B transmitting.

Wireless LAN Protocols (2)Wireless LAN Protocols (2)

The MACA protocol. The MACA protocol.

(a)(a) A sending an RTS to B. A sending an RTS to B.

(b)(b) B responding with a CTS to A. B responding with a CTS to A.

EthernetEthernet• 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

Ethernet CablingEthernet Cabling

The most common kinds of Ethernet cabling. The most common kinds of Ethernet cabling.

o 10Base5 10Base5 disebut juga Thick Ethernet, disebut juga Thick Ethernet, dihubungkan dengan Vampire tap.dihubungkan dengan Vampire tap.

Pd 10Base5 dihubungkan ke transceiver Pd 10Base5 dihubungkan ke transceiver yang mempunyai el-circuit sbg pendeteksi yang mempunyai el-circuit sbg pendeteksi collisioncollision

Controller bertanggung jawab thd Controller bertanggung jawab thd essembling data kedalam format yang essembling data kedalam format yang sesuai.sesuai.

o 10Base2 10Base2 disebut juga Thin Ethernet disebut juga Thin Ethernet dihubungkan dengan BNC yang mem- dihubungkan dengan BNC yang mem-

bentuk T junction bentuk T junction BNC T junction BNC T junction connector.connector.

o 10BaseT 10BaseT menggunakan Twist pair cable menggunakan Twist pair cable dilengkapi dengan HUBdilengkapi dengan HUB

Pd 10BaseT – tidak ada share cable, masing2 Pd 10BaseT – tidak ada share cable, masing2 stasiun dihubungkan ke HUB dengan stasiun dihubungkan ke HUB dengan dedicated cable.dedicated cable.

o 10BaseF 10BaseF menggunakan Fiber Optik menggunakan Fiber Optik - mahal, - mahal, - mempunyai security/ noise imunnity yang- mempunyai security/ noise imunnity yang bagusbagus - lebih susah pemasangannya dp yang - lebih susah pemasangannya dp yang lainnyalainnya - digunakan terutama untuk antar bangunan- digunakan terutama untuk antar bangunan

Ethernet Cabling (2)Ethernet Cabling (2)Three kinds of Ethernet cabling. Three kinds of Ethernet cabling.

(a)(a) 10Base5, 10Base5, (b)(b) 10Base2, 10Base2, (c)(c) 10Base-T. 10Base-T.

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

Ethernet Cabling (3) – Cable Ethernet Cabling (3) – Cable TopologiesTopologies

a)a) Linear (Room-room) Linear (Room-room) b)b) Spine (basement-roof) Spine (basement-roof)c)c) Tree (general topology) Tree (general topology) d) d) Segmented (per Segmented (per segment)segment)

Ethernet Cabling (4)Ethernet Cabling (4)

(a)(a) Binary encoding, Binary encoding, (b)(b) Manchester encoding Manchester encoding,,

(c)(c) Differential Manchester encoding. Differential Manchester encoding.Ethernet tidak menggunakan Diff M.EEthernet tidak menggunakan Diff M.E

Ethernet MAC Sublayer Ethernet MAC Sublayer ProtocolProtocol

Frame formats. Frame formats. (a)(a) DIX Ethernet, DIX Ethernet, (b)(b) IEEE 802.3. IEEE 802.3.

DIX = DEC, Intel, XeroxDIX = DEC, Intel, Xerox

Coax Cable segment

( 500 m max )

Transceiver cable 50 m max

Coax cable

Transceiver and

connection to coax cable - 100 m max

per segment

stasiun

Batasan-batasan single Ethernet cable segment

Konfigurasi Ethernet - Yang Konfigurasi Ethernet - Yang “besar”“besar”

Seg 1 Seg 2

Seg 4 Seg 5

stasiun

repeater

Seg 3Kabel koox

Remote repeater

Point to point link

Periode waktu dari mulainya transmisi, Periode waktu dari mulainya transmisi, selama stasiun selama stasiun pada pada “vulnareble to collision”.“vulnareble to collision”.

Contoh dalam kondisi terjelek sebagai Contoh dalam kondisi terjelek sebagai berikut :berikut :

Bila waktu propagasi sinyal dari ujung ke Bila waktu propagasi sinyal dari ujung ke ujung jaringan adalah : 22,5 ujung jaringan adalah : 22,5 sec yaitu = 225 sec yaitu = 225 bit times pada 10 Mbpsbit times pada 10 Mbps

Collision WindowCollision Window - minimum packet size - minimum packet size

Sesaat sebelum paket A sampai, B mengirim Sesaat sebelum paket A sampai, B mengirim paket paket tabrakan tabrakan

A mendengar ada tabrakan setelah : A mendengar ada tabrakan setelah : (t+22,5)+22,5 (t+22,5)+22,5 secsec

atau : 45 atau : 45 sec = 450 bit time sesudah A mulai sec = 450 bit time sesudah A mulai mengirimmengirimCollision WindowCollision Window : 450 bit time : 450 bit time

A

B

t + st

Pada saat ‘ t’ mulai transmisi t + 22.5 paket dari A

hampir sampai di B

Minimum paket size : 64 oktetsMinimum paket size : 64 oktets

64 oktet = 64 x 8 x 0,1 = 51,2 64 oktet = 64 x 8 x 0,1 = 51,2 secsec

atau = 512 bit timesatau = 512 bit times

Minimum paket harus > dari collision Minimum paket harus > dari collision window window

Bagaimana kalau < ??Bagaimana kalau < ?? Pada Ethernet : tidak menjamin pesan Pada Ethernet : tidak menjamin pesan

akan sampai ditujuan pada waktu yang akan sampai ditujuan pada waktu yang pasti pasti non deterministiknon deterministik

Ethernet MAC Sublayer Protocol Ethernet MAC Sublayer Protocol (2)(2)

Collision detection can take as long as 2 .

Back Off AlgorithmBack Off Algorithm

Untuk meng-akomodasikan jarak terjauh yang Untuk meng-akomodasikan jarak terjauh yang dibolehkan oleh ethernet, slot time harus min 512 dibolehkan oleh ethernet, slot time harus min 512 bit time atau 51,2 bit time atau 51,2 µµsecsec

Setelah tabrakan yang pertama Setelah tabrakan yang pertama harus harus menunggu 0 atau 1 slot time sebelum mengirm menunggu 0 atau 1 slot time sebelum mengirm lagi. Setelah tabrakan yang kedua lagi. Setelah tabrakan yang kedua harus harus menunggu 0,1,2,3 random….dstmenunggu 0,1,2,3 random….dst

Setelah tabrakan n kali harus Setelah tabrakan n kali harus menunggu 0 menunggu 0 sampai 2sampai 2nn-1 random.-1 random.

Algoritma ini disebut : Algoritma ini disebut : Binary Exponential BackoffBinary Exponential Backoff

Binary Exponential Back Off Binary Exponential Back Off AlgorithmAlgorithm

Setelah tabrakan ke-1 Setelah tabrakan ke-1 menunggu 0-1 slot menunggu 0-1 slot time sebelum mengirim lagi.time sebelum mengirim lagi.

Setelah tabrakan ke-2 Setelah tabrakan ke-2 menunggu menunggu 0,1,2,atau 3 slot time sebelum mengirim lagi.0,1,2,atau 3 slot time sebelum mengirim lagi.

Dan seterusnya Dan seterusnya tabrakan ke-n , harus tabrakan ke-n , harus menunggu 2menunggu 2nn - 1 - 1

Disebut Binary Exponential Back Off Disebut Binary Exponential Back Off Algorithm.Algorithm.

Bila tabrakan sampai 16x Bila tabrakan sampai 16x dianggap jaringan dianggap jaringan rusakrusak

Ethernet PerformanceEthernet PerformanceEfficiency of Ethernet at 10 Mbps with 512-bit Efficiency of Ethernet at 10 Mbps with 512-bit

slot times.slot times.

Switched EthernetSwitched EthernetA simple example of switched Ethernet.A simple example of switched Ethernet.

Containing a high speed back plane and Containing a high speed back plane and room for typlcally 4 – 32 plug-in line card, room for typlcally 4 – 32 plug-in line card, each containing 1 to 8 connector. Most each containing 1 to 8 connector. Most Often each connector has a 10 Base=T twist Often each connector has a 10 Base=T twist pair connection to a single host computer.pair connection to a single host computer.

Each card forms its own Each card forms its own collision domain collision domain independent of the otherindependent of the other

Switched EthernetSwitched Ethernet

Switched EthernetSwitched Ethernet Trafik meningkat pada Ethernet diatasi dengan :Trafik meningkat pada Ethernet diatasi dengan : Menambah kecepatan mis. menjadi 100 Mbps Menambah kecepatan mis. menjadi 100 Mbps

atau 1 Gbpsatau 1 Gbps Menggunakan Switched EthernetMenggunakan Switched Ethernet Switch berisi high speed backplane dan card yang Switch berisi high speed backplane dan card yang

masing2 terdiri dari 1-8 konektormasing2 terdiri dari 1-8 konektorBila st mau mengirim Ethernet frameBila st mau mengirim Ethernet frameke switch. ke switch.

Card check, apakah tujuannya ada pada card yang Card check, apakah tujuannya ada pada card yang sama. Bila ya, tinggal dicopy. Bila tidak dikirim sama. Bila ya, tinggal dicopy. Bila tidak dikirim lewat high speed backplane ke card di tujuan.lewat high speed backplane ke card di tujuan.

Bagaimana kalau ada 2 mesin attach ke plug in card Bagaimana kalau ada 2 mesin attach ke plug in card yang sama dan transmit frame pada saat yang sama dan transmit frame pada saat bersamaan? – Coba dipikirkan.bersamaan? – Coba dipikirkan.

Development of Ethernet by increasing Development of Ethernet by increasing thespeed, using more than 10 Mbps. Using thespeed, using more than 10 Mbps. Using Fiber CabelFiber Cabel

One was called FDDI ( Fiber Distributed One was called FDDI ( Fiber Distributed Data Interchange or Fiber ChannelData Interchange or Fiber Channel

Must be compatible with Classic EthernetMust be compatible with Classic Ethernet

Fast EthernetFast Ethernet


Merupakan pengembangan dari Ethernet, Merupakan pengembangan dari Ethernet, dengan menaikkan kecepatan-nya.dengan menaikkan kecepatan-nya.

Muncul : FDDI (Fiber Distributed Data Muncul : FDDI (Fiber Distributed Data Interface) dan Fibre-Channel yang keduanya Interface) dan Fibre-Channel yang keduanya menggunakan Fiber Optik, menggunakan menggunakan Fiber Optik, menggunakan back-bone dan station management yang back-bone dan station management yang complicated complicated tidak dipakai lagi.tidak dipakai lagi.

Kemudian Fast Ethernet yang intinya harus Kemudian Fast Ethernet yang intinya harus kompatible dengan Ethernet sebelumnya.kompatible dengan Ethernet sebelumnya.

Kecepatannya menjadi :100 Mbps,Kecepatannya menjadi :100 Mbps,


The original fast Ethernet cabling.The original fast Ethernet cabling.

Gigabit EthernetGigabit Ethernet Lebih cenderung ke hubungan point to point Lebih cenderung ke hubungan point to point

tidak multidrop seperti Ethernet original 10 tidak multidrop seperti Ethernet original 10 Mbps Mbps Classic Ethernet (lihat gambar)Classic Ethernet (lihat gambar)

Ada 2 mode operasi yang berbeda :Ada 2 mode operasi yang berbeda :

1.Full duplex 1.Full duplex trafik 2 arah pd waktu yang sama, trafik 2 arah pd waktu yang sama, apabila menggunakan sentral switch yg apabila menggunakan sentral switch yg dihubungkan ke pc. Dilakukan pembufferan, dihubungkan ke pc. Dilakukan pembufferan, shg frame bisa dikirim kapan sajashg frame bisa dikirim kapan saja

Tidak perlu mengamati saluranTidak perlu mengamati saluran Switch bebas mix dan match kecepatanSwitch bebas mix dan match kecepatan

2.Half Duplex 2.Half Duplex Bila pc dihubungkan ke HUB Bila pc dihubungkan ke HUB bukan switch. HUB tidak melakukan pem- bukan switch. HUB tidak melakukan pembufferan frame yang datang.bufferan frame yang datang.

Masih mungkin terjadi tabrakan Masih mungkin terjadi tabrakan diperlu kan diperlu kan standard CSMA/CDstandard CSMA/CD

Kecepatan transmisi 100x lebih dp Classic Kecepatan transmisi 100x lebih dp Classic Ethernet, jarak 100x kurang dp Classic Ethernet, jarak 100x kurang dp Classic Ethernet (25 m).Ethernet (25 m).

Untuk mengatasi ini ditambahkan Untuk mengatasi ini ditambahkan (jelaskan!)(jelaskan!)

- Carrier Extention - Carrier Extention

- Frame bursting- Frame bursting

Gigabit EthernetGigabit Ethernet

(a)(a) A two-station Ethernet.A two-station Ethernet.

(b)(b) A multistation Ethernet.A multistation Ethernet.

Gigabit Ethernet (2)Gigabit Ethernet (2)

Gigabit Ethernet cabling.Gigabit Ethernet cabling.

IEEE 802.2: Logical Link ControlIEEE 802.2: Logical Link Control

(a)(a) Position of LLC. Position of LLC. (b)(b) Protocol Protocol formats.formats.

Token busToken busToken RingToken Ring

Wireless LANsWireless LANs

• The 802.11 Protocol StackThe 802.11 Protocol Stack

• The 802.11 Physical LayerThe 802.11 Physical Layer

• The 802.11 MAC Sublayer The 802.11 MAC Sublayer ProtocolProtocol

• The 802.11 Frame StructureThe 802.11 Frame Structure

• ServicesServices

3 teknik transmisi pada wireless :3 teknik transmisi pada wireless :

Infra-red Infra-red seperti remote control pada TV 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 Kecep : 1 Mbps menggunakan 4 ke 16 bit

code word(kombinasi 15 - 0 dan satu -1) code word(kombinasi 15 - 0 dan satu -1) gray codegray code

• 2 Mbps menggunakan 2 ke 4 bit coceword 2 Mbps menggunakan 2 ke 4 bit coceword satu -1 (0001,0010 dll)satu -1 (0001,0010 dll)

The 802.11 Protocol StackThe 802.11 Protocol Stack

Short range radio Short range radio FHSS ( Freq Hopping Spread FHSS ( Freq Hopping Spread Spectrum) dan DSSS( Direct sequence Spread Spectrum) dan DSSS( Direct sequence Spread Sectrum)Sectrum)

• Menggunakan 79 kanal masing2 1 MHzMenggunakan 79 kanal masing2 1 MHz• tanpa ijin (2.4 GHz ISM band) mis: remote pintu tanpa ijin (2.4 GHz ISM band) mis: remote pintu

garasi, microwave oven, cordless telephone ( 1-2 garasi, microwave oven, cordless telephone ( 1-2 Mbps)Mbps)

• DSSS 1 atau 2 Mbps mirip dengan sistem CDMA. DSSS 1 atau 2 Mbps mirip dengan sistem CDMA. Masing2 dikirim dengan 11 chips dengan Masing2 dikirim dengan 11 chips dengan menggunakan : menggunakan : Barker sequence.Barker sequence. Menggunakan Menggunakan PSM.PSM.


OFDM(Orthogonal-FDM) dan OFDM(Orthogonal-FDM) dan HR(High Rate)-DSSS bekerja pada HR(High Rate)-DSSS bekerja pada sampai 54 Mbps dan 11 Mbpssampai 54 Mbps dan 11 Mbps


The 802.11 Protocol StackThe 802.11 Protocol StackPart of the 802.11 protocol stack.Part of the 802.11 protocol stack.

The 802.11 MAC Sublayer ProtocolThe 802.11 MAC Sublayer Protocol

(a)(a) The hidden station problem. The hidden station problem.(b)(b) The exposed station problem. The exposed station problem.

The 802.11 MAC Sublayer Protocol (2)The 802.11 MAC Sublayer Protocol (2)The use of virtual channel sensing using The use of virtual channel sensing using

CSMA/CA.CSMA/CA.

The 802.11 MAC Sublayer Protocol The 802.11 MAC Sublayer Protocol (3)(3)

A fragment burst.A fragment burst.

The 802.11 MAC Sublayer Protocol The 802.11 MAC Sublayer Protocol (4)(4)

Interframe spacing in 802.11.Interframe spacing in 802.11.

The 802.11 Frame StructureThe 802.11 Frame Structure

The 802.11 data frame.The 802.11 data frame.

802.11 Services802.11 Services

• AssociationAssociation

• DisassociationDisassociation

• ReassociationReassociation

• DistributionDistribution

• IntegrationIntegration

Distribution Services

802.11 Services802.11 Services

• AuthenticationAuthentication

• DeauthenticationDeauthentication

• PrivacyPrivacy

• Data DeliveryData Delivery

Intracell Services

Broadband WirelessBroadband Wireless

• Comparison of 802.11 and 802.16Comparison of 802.11 and 802.16

• The 802.16 Protocol StackThe 802.16 Protocol Stack

• The 802.16 Physical LayerThe 802.16 Physical Layer

• The 802.16 MAC Sublayer The 802.16 MAC Sublayer ProtocolProtocol

• The 802.16 Frame StructureThe 802.16 Frame Structure

The 802.16 Protocol StackThe 802.16 Protocol StackThe 802.16 Protocol Stack.The 802.16 Protocol Stack.

The 802.16 Physical LayerThe 802.16 Physical LayerThe 802.16 transmission environment.The 802.16 transmission environment.

The 802.16 Physical Layer (2)The 802.16 Physical Layer (2)Frames and time slots for time division Frames and time slots for time division

duplexing.duplexing.

The 802.16 MAC Sublayer The 802.16 MAC Sublayer ProtocolProtocol

Service ClassesService 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 Non-real-time variable bit rate serviceservice

• Best efforts serviceBest efforts service

The 802.16 Frame StructureThe 802.16 Frame Structure(a)(a) A generic frame. A generic frame.

(b)(b) A bandwidth request frame.A bandwidth request frame.

BluetoothBluetooth

• 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

Bluetooth ArchitectureBluetooth ArchitectureTwo piconets can be connected to form a Two piconets can be connected to form a

scatternet.scatternet.

Bluetooth ApplicationsBluetooth ApplicationsThe Bluetooth profiles.The Bluetooth profiles.

The Bluetooth Protocol StackThe Bluetooth Protocol StackThe 802.15 version of the Bluetooth protocol The 802.15 version of the Bluetooth protocol

architecture.architecture.

The Bluetooth Frame StructureThe Bluetooth Frame Structure

A typical Bluetooth data frame.A typical Bluetooth data frame.

Data Link Layer SwitchingData 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, Repeaters, Hubs, Bridges, Switches, Routers, GatewaysRouters, Gateways

• Virtual LANsVirtual LANs

To connect LAN-LANTo connect LAN-LAN On the Data Link LayerOn the Data Link Layer Usually for 802 LANUsually for 802 LAN Only discuss Bridge - 802Only discuss Bridge - 802

The reason why an organization using several The reason why an organization using several LANLAN

1.1. Different needs of many Different needs of many Universit Universitiesies / /

DepartemenDepartementsts Several Several LAN LAN need need bridgebridge

BRIDGEBRIDGE

2. 2. The different geographies – many The different geographies – many

building in the separate areabuilding in the separate area

3. 3. OverloadOverload - - thousandsthousands workstation workstation

- Need to divided into several LAN- Need to divided into several LAN

- Need- Need Bridge Bridge

4.4.The distance between machines too farThe distance between machines too far

((mis. 802.3 > 2,5 km) mis. 802.3 > 2,5 km) Using the single cable – the Using the single cable – the round trip delay round trip delay is is

largelarge Need dividedNeed divided into several into several LANLAN Need Need bridgebridge

5.5.Bridge Bridge can select which is continue or notcan select which is continue or not using programmingusing programming not only copynot only copy RepeaterRepeater

6.Bridge 6.Bridge support security to the organizationsupport security to the organization

The problem of theThe problem of the BRIDGE BRIDGE betweenbetween

802.X DAN 802.Y802.X DAN 802.Y1.1. 1.1. Each using the different frame Each using the different frame

formatformat.. 802.3 : Xerox802.3 : Xerox 802.4 : General motor, Boing, Motorola 802.4 : General motor, Boing, Motorola

does not want to change does not want to change not compatiblenot compatible 802.5 : IBM802.5 : IBM

2.2. 802.3 802.3 allowedallowed 1 - 20 Mbps (10 Mbps) 1 - 20 Mbps (10 Mbps)

802.4 802.4 allowedallowed 1 - 10 (10 Mbps) 1 - 10 (10 Mbps)

802.5 802.5 allowedallowed 1 - 4 Mbps (4 Mbps) 1 - 4 Mbps (4 Mbps)

TheThe 802.3 / 802.4 802.3 / 802.4 toto 802.5 buffer 802.5 buffer neededneeded

TheThe 802.4 ke 802.3 802.4 ke 802.3 needneed band band width width expansion because there isexpansion because there is collision collision inin 802.3’S 802.3’S

3. The differences between3. The differences between maxmaximumimum frame lengthframe length

802.3 : 1518 bytes802.3 : 1518 bytes 802.4 : 8191 bytes802.4 : 8191 bytes 802.5 : 802.5 : unlimitedunlimited, , depend ondepend on THT THT The The defaultdefault of of THT 10 msec THT 10 msec 5000 5000

bytesbytes

P SD AC FC DA/SA L D PAD CS ED FS

IEEE 802 Frame-format

802-3

802-4

802-5

Another ProblemsAnother Problems : : 802.3 ke 802.3 : 802.3 ke 802.3 : no problemno problem 802.4 ke 802.3 : 802.4 ke 802.3 : there arethere are 2 2 problems :problems :

802.4 802.4 hashas preorit preorityy, 802.3 , 802.3 does not has does not has priority priority ignoredignored– 802.4 802.4 has 1 bit in the header ashas 1 bit in the header as

sender, sender, token ack token ack from from destination . destination .

802.5 802.5 toto 802.3 802.3 also has problem as also has problem as aboveabove

Bridges from 802.x to 802.yBridges from 802.x to 802.yOperation of a LAN bridge from 802.11 to Operation of a LAN bridge from 802.11 to

802.3.802.3.

Bridges from 802.x to 802.y (2)Bridges from 802.x to 802.y (2)The IEEE 802 frame formats. The drawing is The IEEE 802 frame formats. The drawing is

not to scale.not to scale.

Local InternetworkingLocal InternetworkingA configuration with four LANs and two A configuration with four LANs and two

bridges.bridges.

TRANSPARENT BRIDGETRANSPARENT BRIDGE

Every things are transparentEvery things are transparent Just plug between networks without any Just plug between networks without any

changes at all changes at all the system will run the system will run Works asWorks as, ‘promises mode’, , ‘promises mode’, receive receive

everyevery frame frame,, send to many LAN and send to many LAN and many directionmany direction

Bridge Bridge worksworks depend on address table in depend on address table in the bridge to find which frame discard or the bridge to find which frame discard or not. not.

Routing procedure Routing procedure depend on sender depend on sender and frame’s receiver and frame’s receiver

a)a) If receiver and sender comes from If receiver and sender comes from the same LAN the same LAN frame will be discard frame will be discard

b) b) If receiver and sender comes from If receiver and sender comes from the different LAN the different LAN frame will be pass frame will be pass

c)c) If receiver and sender not clear If receiver and sender not clear and unknown and unknown using flooding using flooding

Flooding : Flooding : sometimes create the sometimes create the troubletrouble because they must copy every because they must copy every frameframe Handle byHandle by Spanning Tree Spanning Tree BridgeBridge

Spanning Tree BridgesSpanning Tree BridgesTwo parallel transparent bridges.Two parallel transparent bridges.

Spanning Tree Bridges (2)Spanning Tree Bridges (2)

(a)(a) Interconnected LANs. Interconnected LANs. (b)(b) A spanning tree A spanning tree covering the LANs. The dotted lines are not covering the LANs. The dotted lines are not part of the spanning tree.part of the spanning tree.

Remote BridgesRemote BridgesRemote bridges can be used to interconnect Remote bridges can be used to interconnect

distant LANs.distant LANs.

Repeaters, Hubs, Bridges, Repeaters, Hubs, Bridges, Switches, Routers and GatewaysSwitches, Routers and Gateways

(a)(a) Which device is in which layer. Which device is in which layer.

(b)(b) Frames, packets, and headers. Frames, packets, and headers.

Repeaters, Hubs, Bridges, Switches, Repeaters, Hubs, Bridges, Switches, Routers and Gateways (2)Routers and Gateways (2)

(a)(a) A hub. A hub. (b)(b) A bridge. A bridge. (c)(c) a switch. a switch.

Virtual LANsVirtual LANsA building with centralized wiring using hubs A building with centralized wiring using hubs

and a switch.and a switch.

Virtual LANs (2)Virtual LANs (2)

(a)(a) Four physical LANs organized into two VLANs, Four physical LANs organized into two VLANs,

gray and white, by two bridges. gray and white, by two bridges.

(b)(b) The same 15 machines organized into two The same 15 machines organized into two

VLANs by switches.VLANs by switches.

The IEEE 802.1Q StandardThe IEEE 802.1Q StandardTransition from legacy Ethernet to VLAN-aware Transition from legacy Ethernet to VLAN-aware Ethernet. The shaded symbols are VLAN aware. Ethernet. The shaded symbols are VLAN aware.

The empty ones are not.The empty ones are not.

The IEEE 802.1Q Standard (2)The IEEE 802.1Q Standard (2)

The 802.3 (legacy) and 802.1Q Ethernet The 802.3 (legacy) and 802.1Q Ethernet frame formats.frame formats.

SummarySummary

Channel allocation methods and systems for a common channelChannel allocation methods and systems for a common channel..

Documents

The Medium Access Control Sublayer