Introduction to OSI lower Layer Kentaro Hayashi Graduate school of Information Science and Electrical Engineering Department of Advanced Information Tec hnology Kyushu University
Dec 26, 2015
Introduction to OSI lower Layer
Kentaro HayashiGraduate school of Information Science and Electric
al EngineeringDepartment of Advanced Information Technology
Kyushu University
2
Contents
OSI Reference Model
Physical Layer
Date Link Layer
Network Layer
3
OSI Reference Model
4
Example of Layer Model・ Postal Mail Service
Contents Simple, Plain
Representation
Language, Meaningful Sentence
Postal format
Post Code, Address, Name, Postcard
Transportation method
Motor bike, Truck, Train
sender
Some post offices
receiver
5
OSI Reference Model・ Open Systems Interconnection Reference Model・ In 1977, work on a layered model of network architectur
e, which was to become the OSI model, started in the American National Standards Institute (ANSI) working group on Distributed Systems (DISY). With the DISY work and worldwide input, the International Organization for Standardization(ISO) began to develop its OSI networking suite.
・ OSI has two major components: an abstract model of networking (the Basic Reference Model, or seven-layer model) and a set of concrete protocols. [Wikipedia]
6
OSI reference model
Application
Presentation
Session
Transport
Network
Data Link
PhysicalLayer 1
Layer 2
Layer 3
Layer 4
Layer 5
Layer 6
Layer 7
Media, signal and binary transmission
Physical addressing
Path determination and logical addressing
End-to-end connections and reliability
Signaling for session
Data representation and encryption
Network process to application
offer service
offer communication
7
OSI Upper Layer
Layer 5
Layer 6
Layer 7 Application
Presentation
Session
Application
DATADATA
Format
When to start
Signaling
8
OSI Lower Layer
Transport
Network
Data Link
PhysicalLayer 1
Layer 2
Layer 3
Layer 4 Reliability
0101
0101Data transmissionat the node interval
Routing
Physical connection
9
Physical Layer
Transport
Network
Data Link
PhysicalLayer 1
Layer 2
Layer 3
Layer 4
10
Physical Layer
The Physical Layer defines the electrical and physical specifications for devices. In particular, it defines the relationship between a device and a physical medium. This includes the layout of pins, voltages, cable specifications, Hubs, repeaters, network adapters, and more.
[Wikipedia]
11
Cable
Coaxial Cable Twisted Pear Cable Optical Fiber Wireless
12
Coaxial cable
1. Inner conductor2. Insulator surrounding the Inner conductor3. Metallic shield and outer conductor4. Outer insulating jacket
Characteristic
・ Few leaks of the electromagnetic wave to the outside.・ Able to bend.・ Able to transmit of a wide frequency range.・ Structure is complicated, and price is high.
13
Twisted pair cableSTP (Shielded twisted pair)UTP (Unshielded twisted pair)
TX +TX -RX +RX -
TX : Transmit pairRX : Receive pair
Characteristic
・ Cheap and Easy to treat.・ Wire freely.・ Affected by the powerful electricity and electromagnetic .
14
Optical fiber
Core : Light advances.
Cladding : Light is reflected.
Buffer : Relax shock, absorbent
Jacket : Protect.
15
Multi mode Single mode
・ Strong to bend.・ Easy to connect.・ Cheap.・ Made of plastic.(Cladding:fluorine-based polymer)
・ Little transmission loss.・ Made of quartz glass.( Core:Ge,P , Cladding:B,F)
16
Wireless Communication
【 Radio 】・ Electric wave
・ Unnecessary line of sight
( ・ license is necessary)
・ mobile phone, PHS
・ Bluetooth (IEEE 802.15.1)
【 FSO 】 Free Space Optics
・ Infrared ray (IR)or Visible spectrum
・ line of sight is required・ license is unnecessary・ PC, remote controller・ IrDA UFIR⇒
・ The wiring space is unnecessary.
・ Mobile communication is possible.
・ Able to build LAN immediately.
・ Able to communicate outdoors.
17
Encoding・ NRZ(Non-Return to Zero)
0 → Low Level 1 → Hi Level
※ 1000BASE-X
・ NRZI(Non-Return to Zero Inversion)
0 → No Change Level 1 → Change Level
※ FDDI, 100BASE-FX
・ Manchester0 → Hi ⇒Low1 → Low⇒Hi
※ 10BASE5 、 2 、 -T
・ MLT-3 0 → No Change Level
1 → Change Level (Middle⇒Hi⇒Middle⇒Low )⇒
※ 100BASE-TX 、 CDDI
18
Encoding
19
Protocol
・ RS-232C (Recommended Standard 232C)
・ ISDN (Integrated Services Digital Network)
・ xDSL (x Digital Subscriber Line)
- ADSL (Asymmetric DSL)
・ IEEE 802.11 (Wireless LAN)
・ SDH (Synchronous Digital Hierarchy)
SONET (Synchronous Optical NETworking)
・ Protocol for Ethernet
20
IEEE 802.11
⇒one of the wireless LAN related standards
Release DateFrequency
bandOfficial speed
IEEE 802.11 1997 2.4 ~ 2.5GHz 2Mbps
IEEE 802.11b
October, 1999
2.4 ~ 2.5GHz11Mbps /
22Mbps
IEEE 802.11a
October, 1999
5.15 ~ 5.35GHz5.47 ~
5.725GHz(Max)54Mbps
IEEE 802.11g
June, 2003 2.4 ~ 2.5GHz 54Mbps
IEEE 802.11j --4.9 ~ 5.0GHz
5.03 ~5.091GHz
54Mbps
IEEE 802.11n
-- 2.4GHz / 5GHz 100Mbps ~
21
SONET/SDH⇒ The international standard
of the high speed digital communication method with optical fiber
SONET SDHTransmission
speed
OC-1 ‐ 51.84Mbps
OC-3 STM-1 155.52Mbps
OC-9 ‐ 466.56Mbps
OC-12 STM-4 622.08Mbps
OC-18 ‐ 933.12Mbps
OC-24 ‐ 1244.16Mbps
OC-36 ‐ 1,866.24Mbps
OC-48STM-
162,488.32Mbps
OC-192STM-
649,953.28Mbps
OC : Optical Carrier
22
Protocol for Ethernet Transmission
speedMaximum length Cable Encoding
10BASE-5 10Mbps 500m Coaxial cable Manchester
10BASE-2 10Mbps 185m Coaxial cable Manchester
10BASE-T 10Mbps 100mTwisted pair
cableManchester
100BASE-TX 100Mbps 100mTwisted pair
cable4B/5B + MLT-
3
1000BASE-T 1Gbps 100mTwisted pair
cable4D-
PAM5(8BIQ4)
100BASE-FX 100Mbps
Multi mode:412m(half duplex)
Optical fiber 4B/5B + NRZI2km(full duplex)
Single mode:20km(full duplex)
1000BASE-SX 1Gbps Multi mode:550m Optical fiber 8B/10B + NRZ
1000BASE-LX 1GbpsMulti mode:550m
Optical fiber 8B/10B + NRZSingle mode:5km
1000BASE-ZX 1Gbps 100km Optical fiber 8B/10B + NRZ
23
Data Link Layer
Transport
Network
Data Link
PhysicalLayer 1
Layer 2
Layer 3
Layer 4
24
Date Link Layer
The Date Link Layer provides the functional and procedural means to transfer data between network entities and to detect and possibly correct errors that may occur in the Physical Layer.
25
Protocol
IEEE802.3 (Ethernet) FDDI (Fiber distributed data interface) ATM (Asynchronous Transfer Mode) PPP (Point-to-Point Protocol) Token Ring ARP (Address Resolution Protocol) IEEE802.11(wireless LAN)
26
Ethernet The protocol that spreads in LAN most today American Xerox company, Intel Company and old DEC
Company devised Standardized by IEEE802.3 afterwards As for these 2, the forms of the frame are different CSMA/CD
27
Frame Format
Data46~1500
Data38~1492
Destination MAC address
6
Destination MAC address
6
SourceMAC address
6
Source MAC address
6
Type2
SNAP5
Length2
LLC3
FCS4
FCS4
Ethernet
IEEE802.3 Ethernet
Preamble8octets
Preamble8
MTU(Maximum Transmission Unit)1518bytes
8 bits = 1 bytes = 1 octets
28
MAC address Media Access Control address Standardized by IEEE802.3 The unique address that was allotted to the NIC(Network Interfa
ce Card)
22bits 24bits1
bits1
bits
48bits
29
MAC address
NIC receives the Frame which destination MAC address is same as own one.
A B C Ddatadata
× ×○
The destination MAC address is C
30
Collision Each terminal controls it autonomously to avoid a
collision of the communication In order to avoid collision, Ethernet use CSMA/CD.
A B C Ddatadata data
Collision
To C To D
31
CSMA/CD(Collision Detection)
Non-persistent CSMA + While itself transmits a message, It examines that there are only it's data in a network
If a collision happens, It waits in random time and retransmits afterwards
When a collision occurs more than the constant number of times, It stops the transmission of a message.
32
CSMA(Carrier Sense Multiple Access) Each terminal controls it autonomously to avoid a
collision of the communication The transmission of a data is performed unless a signal
is passed to LAN
A B C Ddata data
Collision
data data
33
Switch (Switching Hub) Filtering by the MAC address I t decides the port which It should send
A B C Ddatadata
○
switch
To C
data
To D ○
34
Network Layer
Transport
Network
Data Link
PhysicalLayer 1
Layer 2
Layer 3
Layer 4
35
Network Layer
Network Layer is
36
IP
Protocol developed in U.S. Department of Defense (DoD) to bear network layer of TCP/IP model
IP is a protocol of a connectionless type
37
IP
IP maintains the logic address that is called IP address in all machines on the network IP address is hierarchized structure and keep
unique all over the world
The relay node of IP is called a router.
38
IP packet formatVersion
(4)
Header Length
(4)
Service Type
(8)
Packet Length
(16)
ID
(16)
Flag
(3)
Fragment Offset
(13)
TTL
(8)
Protocol
(8)
Header Check-Sum
(16)
Transmission former IP address
(32)
Destination IP address
(32)
Option
(32 * n)
Data
39
IP address
Logic address used by IP protocol When you write Internet Protocol address
32 all bits are written by one byte by the decimal number with the dot separately for four parts (octet) ( 例 ) 11010011 00000111 01011010 01110001 → 211.7.90.113
Network address
n bits
Host address
(32 –n) bits
40